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X-RAY RUNS: Apply for Beamtime

2017  May 17 - Jun 29

2017  Nov 1 - Dec 21

Poster Abstracts

 

"Double Laue Monochromator for High Energy X-rays: Designing and Commissioning of a Prototype, and Planned Upgrade"

J. Y. Peter Ko1, Benjamin B. Oswald1, James J. Savino1, Alan K. Pauling1, Darren S. Dale1, Margaret K. A. Koker1, Matthew P. Miller1,2, Joel D. Brock1,3

1 Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY
2 Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY
3 School of Applied and Engineering Physics, Cornell University, Ithaca, NY

Abstract: High-energy X-rays are efficiently focused in the out of scattering plane direction by a set of sagitally-bent, asymmetric Laue crystals [1]. The main advantage of the Laue geometry over the Bragg geometry is the smaller beam footprint on the crystals, and the ability to utilize the anticlastic bending in the meridional plane to eliminate the chromatic aberration of the diffracted beam by working on the Rowland circle [2]. We have designed, built, and commissioned a prototype double-crystal Laue monochromator optimized for high energy X-rays. We characterized several performance parameters such as flux, focal size, energy bandwidth, and angular divergences. Here, we report our design of novel prototype sagittal bender and highlight results from recent characterization experiments. The design of the bender combines the tunable bending control afforded by previous leaf spring designs with the stability and small size of a four bar bender. The prototype monochromator focuses a 25 mm-wide 30 keV X-rays at the upstream monochromator crystal to a 0.6 mm beam waist in the hutch. Compared to flux in the same focal spot, the prototype Laue monochromator delivered 60 times more flux at 30 keV. In addition, the horizontal divergence of the beam can be controlled precisely by varying opening width of the horizontal slits in front of the upstream monochromator without affecting the size of the focal spot in the hutch. Based on the lessons learned from the commissioning experiments, we have designed an improved version of Laue monochromator, which will be installed at the F2 beamline as part of the high-energy X-ray beamline upgrade. The design considerations include bending mechanisms, twist controls, desired ranges and precisions of various movements of the monochromator crystals, and cooling of the upstream monochromator crystal. The beamline is expected to provide the X-rays ranging from 40 to 90 keV, with the beam size of ~1 mm horizontal (focused), and ~3 mm vertical (unfocused). The flux in the focused spot at 40 keV is expected to be 7.5 × 1012 ph/s, with ΔE/E of 2 × 10-3. The installation of the monochromator will take place this summer and commissioning experiments will be performed this fall.

[1] Z. Zhong, C. C. Kao, D. P. Siddons, J. B. Hastings, J. Appl. Cryst. 34, 504-509 (2001)
[2] Z. Zhong, C. C. Kao, D. P. Siddons, J. B. Hastings, J. Appl. Cryst. 34, 646-653 (2001)

 

"The Status of CHESS Capillary Optics Development"

Rong Huang and Thomas Szebenyi
CHESS, Cornell University, Ithaca, NY

Abstract: Ellipsoid shaped single-bounce glass capillaries, fabricated at CHESS, have been used as achromatic X-ray focusing optics for various applications at beamlines. Capillary’s compact dimension provides a high demagnification configuration with short focal distance in both transverse directions, and the capillary’s 360 degree of azimuth angle interception can provide a large X-ray acceptance or a large numerical aperture. Capillary fabrication at CHESS can be customized according to requirements of particular applications, such as microbeam X-ray fluorescence, confocal X-ray microscopy, microcrystallography, small-angle X-ray scattering, high resolution X-ray diffraction and microbeam standing wave technique, high pressure experimentation with diamond anvil cells, full-field transmission X-ray microscopy (TXM), X-ray emission spectroscopy etc.

The features of capillary optics will be briefly summarized in this poster, followed by examples of recently progress on capillary optics development. As we gradually improve the capillary quality, we have successfully achieved 4μm focal size with capillary fully illuminated and 2.7 μm focal size with capillary partially illuminated. One latest application was using CHESS capillaries as the condenser for the APS transmission X-ray Microscopy using the high resolution and high numerical aperture zone-doubled Fresnel Zone Plates (FZPs), which demonstrated that CHESS capillaries are suitable for such large numerical aperture focusing applications. The compact dimension of capillary makes it not only suitable as primary focusing optics but also as secondary focusing optics for maximal flux acceptance, with an example shown in this poster. As capillary fabrication improves, we are also developing a new capillary metrology setup based on a customized airbearing stage to improve measurement accuracy and resolution. Finally, to give users and beamline scientists a good grasp of the broad range of applications of CHESS capillaries, exemplar experiments on several synchrotron facilities in recent years are also given in this poster.

 

"Tunable 2D nanoparticle crystallization in high salt and divalent salt environments with non-base-pairing DNA"

Shawn J. Tan †*, Jason S. Kahn §, Thomas L. Derrien §, Michael J. Campolongo †, Mervin Zhao §, Detlef-M. Smilgies #, Dan Luo §‡*

† Department of Biomedical Engineering, Cornell University, Ithaca, New York 14853, USA
§ Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853, USA
‡ Kavli Institute at Cornell, Cornell University, Ithaca, New York 14853, USA
# Cornell High Energy Synchrotron Source, Cornell University, Ithaca, New York 14853, USA

Abstract: The multiparametric nature of nanoparticle self-assembly make it challenging to circumvent the instabilities that lead to aggregation and achieve crystallization under extreme conditions. With non-base-pairing DNA as a model ligand, we demonstrate that long-range 2D DNA-nanoparticle crystals can be attained in extreme high salt conditions and in divalent salt environment. We further report an empirical model for engineering the interparticle spacing in high monovalent and divalent salt conditions based on ligand length and ionic strength.

 

"Designer Solids: Ambient Structural Control"

Detlef-M. Smilgies
CHESS D1 Station

Abstract: Designer solids consist of complex objects that form regular lattices - the standard example is nanocrystal superlattices, where nanocrystals comprise an inorganic core surrounded by an organic ligand shell [1]. We have found that such materials can be highly tailored to obtain specific lattice parameters and symmetries [2-3]. Another intriguing feature is the ability to orient faceted nanocrystals on their lattice sites within a superlattice [4]. The structural control is achieved by judicious choice of deposition and annealing parameters [5]. We have used in-situ deposition via drop casting [6]or shear coating [7] as well as controlled vapor treatment [8] and drying [6] to prepare well-ordered phases of a specific symmetry. A fascinating aspect is the observation of phase transitions [4,9] as a result of the offered partial pressure of solvent vapor. The controlled vapor environment can also be employed to prepare and study perfectly equilibrated systems [10]. The next step in this project will be to correlate structural properties of the materials with their collective behavior, such as magnetic and optical properties – some first D1 experiments show great promise [11, 12]. As structural properties may depend delicately on environmental conditions such as solvent vapor pressure, such measurements should be done in-situ under structural control via x-ray scattering.

[1] C. P. Collier, T. Vossmeyer, and J. R. Heath, Annu. Rev. Phys. Chem. 49 (1998) 371–404.
[2] Zewei Quan and Jiye Fang, Nano Today 5 (2010) 390—411.
[3] Tobias Hanrath, J. Vac. Sci. Technol. A 30 (2012) 030802.
[4] Kaifu Bian et al., ACS Nano 5 (2011) 2815-2823.
[5] Tobias Hanrath et al., ACS Nano 3 (2009) 2975–2988.
[6] Ruipeng Li et al., Adv. Funct. Mater. 23 (2013) 291–297
[7] Detlef-M. Smilgies et al., Physica Status Solidi –Rapid Research Lett. 7 (2013) 177-179.
[8] Hadayat Ullah Khan et al., ACS Appl. Mater. & Interfaces 5 (2013) 2325−2330.
[9] Jun Zhang et al., JACS 134 (2012) 14043-14049.
[10] Michael Campolongo et al., ACS Nano 5 (2011) 7978-7985.
[11] Aram Amassian et al., J. Mater. Chem. 20 (2010) 2623-2629.
[12] Reken Patel et al., ACS Appl. Mater. & Interfaces 1 (2009) 1339–1346.

 

"X-RAY DIFFRACTION OF ORGANIC CATHODE MATERIALS IN LITHIUM-ION BATTERIES"

Katie Silberstein, Michael Lowe, Weidong Zhou, Jie Gao, Héctor Abruña
School of Chemistry and Chemical Biology, Cornell University, Ithaca NY

Abstract: The Abruña research group has developed and characterized numerous promising materials for battery and fuel cell applications. In the present context, we focus on organic-based battery materials and intend to investigate how molecular structure relates to bulk characteristics of the materials of interest, with emphasis on charge storage. Conventional lithium-ion batteries employ inorganic oxides (e.g. LiCoO2) and graphite (LiC6) as cathode and anode electrodes, respectively. The charge/discharge process involves (de)/intercalation events which are known to be kinetically slow, resulting in low rates of charge and discharge. An alternative, yet relatively unexplored, approach is the use of electroactive organic molecules (in place of the metal oxide) as the cathode in a lithium-ion battery (LIB). Through computational design and screening, combined with synthesis, organic molecules can be tuned over a broad parameter space to yield materials that can exchange multiple electrons per formula unit, leading to high gravimetric capacities. In addition, the formal potentials can be tuned so that theoretical energy densities in excess of 1,500 Wh/kg are possible.

To date, the interactions of lithium ions with these organic materials within a working cell are not well understood. How is the lithium incorporated? Does it intercalate between layers within microcrystals? Does it ionically coordinate to electronegative moieties? By monitoring structural changes of the organic compounds via X-ray diffraction as a function of the state of charge, we can begin to elucidate the molecular mechanism of lithium incorporation that leads to charge storage. Our test system includes anthraquinone and two derivatives with different electron-withdrawing groups. A deeper physical understanding of these materials will allow for a more rational design and, ultimately, more efficient devices.

 

"Global studies of single-stranded nucleic acid conformation"

Julie L. Sutton, Steve P. Meisburger, Huimin Chen, Lois Pollack
Applied and Engineering Physics, Cornell University

Abstract: Unstructured regions of RNA molecules require flexibility to accomplish many biological tasks such as conformational switching and protein recognition. Due to its highly charged backbone, the flexibility of single-stranded RNA is influenced by counterions. In this presentation, we continue to explore RNA flexibility using single-stranded nucleic acid homopolymers as a model system [1]. We investigate the role of counterion valence in nucleic acid flexibility using a combination of small-angle X-ray scattering (SAXS) and single-molecule Förster resonance energy transfer (smFRET). We also study how charge-screening of these model systems are affected by mono- and divalent ions in competition. The results imply that various factors can alter the polymeric properties of unstructured nucleic acids, and may be important for tuning RNA conformational dynamics in vivo.

[1] Chen et al. PNAS 2012 109 (3) 799-804

 

"Using Smart Polymers to Regulate DNA-mediated Nano Assembly"

Kristen L. Hamner1, Detlef Smilgies2, and Mathew M. Maye1*

1Department of Chemistry, Syracuse University, Syracuse New York, 13244
2Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY
*mmmaye@syr.edu

Abstract: In this paper we describe the use of a temperature responsive polymer to regulate DNA interactions in both a DNA-mediated assembly system, as well as a DNA encoded drug delivery system. A thermo-responsive pNIPAAm-co-pAAm polymer, with a transition temperature (TC) of 51C was synthesized with thiol modification, and grafted to gold nanoparticles (Au NPs) also containing single stranded oligonucleotides (ssDNA). The thermo-responsive behavior of the polymer allowed for regulating the accessibility of the sequence-specific hybridization between complementary DNA functionalized Au NPs. At T < TC the polymer was hydrophilic and extended, blocking interaction between the complementary sequences at the periphery of the hydrodynamic diameter. In contrast, at T > TC, the polymer shell undergoes a hydrophilic to phobic phase transition and collapses, shrinking below the outer ssDNA, allowing for the sequence-specific hybridization to occur.

 

"Confined but Connected Quantum Dot Solids"

Kevin Whitham
Materials Science and Engineering, Cornell University, Ithaca, NY

Abstract: Confined but connected quantum dot solids (QDS) combine the advantages of tunable, quantum-confined energy levels with efficient charge transport through enhanced electronic interdot coupling. We report the fabrication of QDSs by treating self-assembled films of colloidal PbSe quantum dots with polar nonsolvents. Treatment with dimethylformamide balances the rates of self-assembly and ligand displacement to yield confined but connected QDS structures with cubic ordering and quasi-epitaxial interdot connections through facets of neighboring dots. The QDS structure was analyzed by a combination of transmission electron microscopy and wide-angle and small-angle X-ray scattering. Excitonic absorption signatures in optical spectroscopy confirm that quantum confinement is preserved. Transport measurements show significantly enhanced conductivity in treated films.

 

"In-situ GIXS Study of P3HT:PCBM Thin Films During Solvent Vapor Annealing and Film Drying"

Abul Huq1, Detlef M. Smilgies2, Jose Chapa1 and Alamgir Karim1

1Department of Polymer Engineering, University of Akron, OH 44325
2Cornell High Energy Synchrotron Source, Ithaca, NY 14853

Abstract: The obvious difference between thin films and bulk materials is that a thin film can be considered as under two dimensionally confined, which in turn may affect polymer crystallization behavior and crystal structures, molecular ordering, morphology, etc. In recent years poly(3-hexylthiophene) (P3HT):1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C61 (PCBM) thin film has drawn tremendous research attention. P3HT is a semicrystalline material, while PCBM is a crystallizable small molecule. Even though this film is extensively studied after post processing by solvent annealing, in-situ solvent annealing study of such films is rather rare . In-situ study enabled us to capture frame by frame GIWAXS images during solvent annealing process. In this way P3HT and PCBM crystal dissolution and growth kinetics during such solvent annealing is directly probed. All studies were conducted approximately for 20 minutes of solvent annealing and subsequent 20 minutes for drying. In this study we varied substrate surface energy and solvents. It is observed that substrate surface energy has immense effect on P3HT crystal growth kinetics. From exposure normalized images it is found that on self-assembled monolayer (SAM) coated silicon (surface energy ~40mJ/m2) P3HT crystal dissolution is much faster than that of UVO treated silicon (surface energy ~70 mJ/m2). All surface energies were obtained by contact angle measurement method. Effect of solvents on crystal dissolution and growth kinetics is rather complex. Crystal dissolution rate largely depends on solubility of P3HT and PCBM, volatility and partial pressure of the solvent under study. However, in all cases much of the crystal dissolution occurs in first minute. During drying cycle crystal formation largely depends on volatility of solvent under study. In the cases where o-xylene, chloroform, toluene and chlorobenzene, were used as solvent for annealing, crystal growth rate is fast during drying cycle. However, we did not observe much crystal growth during drying cycle in the case where o-dichlorobenzene was used during annealing cycle. Since our study only captured 20 minutes of drying in ambient condition it is most likely that absorbed non-volatile o-dichlorobenzene was not evaporated during that time frame. X-ray reflectivity shows that film thickness and roughness increase during solvent annealing and reduce in drying cycle when o-xylene, chloroform, toluene and chlorobenzene, were used during annealing cycle. Smoothness of the films remained intact throughout the study when annealing solvent was o-dichlorobenzene.

 

"Introducing Cryo-SAXS for Measuring Low Resolution Macromolecular Structure without Radiation Damage"

Steve P. Meisburger1, Matthew Warkentin1, Huimin Chen1, Jesse B. Hopkins1, Andrea Katz1, Richard E. Gillilan2, Robert E. Thorne1, and Lois Pollack1

1Cornell University, Ithaca, NY, USA
2MacCHESS, Cornell High Energy Synchrotron Source, Ithaca, NY, USA

Abstract: Small angle X-ray scattering (SAXS) is an increasingly popular technique for obtaining low resolution structures of macromolecules and complexes in solution. However, the susceptibility of biomolecule solutions to damage by ionizing radiation can complicate SAXS experiments. Many potentially interesting proteins, such as light sensors and metalloenzymes, require flow cells to distribute the X-ray dose over a large volume. The high sample consumption in these cases can be prohibitive. To circumvent radiation damage, we explore whether cryo-cooling of samples to temperatures of 100 K can prevent aggregation and fragmentation during data collection. We identify SAXS-friendly cryoprotectant conditions that suppress ice formation upon rapid cooling, and compare cryo-SAXS profiles with room temperature measurements for a variety of standard molecules. From scattering volumes as small as 100 nL, we obtain data of sufficient quality for envelope reconstruction, and find good agreement between cryo-SAXS data and known atomic structures. Strikingly, cryo-cooled samples can withstand doses that are 2-3 orders of magnitude higher than typically used for SAXS at room temperature, comparable to those used in cryo-crystallography. While practical challenges remain, this breakthrough opens the possibility of using SAXS with new, high brightness X-ray sources for high throughput applications.

 

"Mechanistic Study of High Performance Triblock Terpolymer Ultrafiltration Membrane Formation via In Situ GISAXS"

Rachel Mika Dorin1, Yibei Gu1, Detlef-M. Smilgies2, and Ulrich Wiesner1

1Materials Science and Engineering, Cornell University, Ithaca, NY
2Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY

Abstract: The application of block copolymer self-assembly towards membrane separations has received significant attention over the past several years due to the potential for significantly improved performance. In particular, the combination of self-assembly and non-solvent induced phase separation (SNIPS)1 produces integral isoporous membranes. Using this facile and industrially scalable method, membranes have been fabricated from a variety of block copolymers, including poly(styrene-b-4-vinyl pyridine),2 poly(styrene-b-2-vinyl pyridine),3 poly(styrene-b-ethylene oxide),4 poly(styrene-b-2-vinyl pyridine-b-ethylene oxide),5 and poly(isoprene-b-styrene-b-4-vinyl pyridine).6 These SNIPS membranes exhibit exceptional fluxes and high-resolution separations, as well as the capacity for post-functionalization, leading to temperature-dependent performance7 and charge-based separations8. While functional membranes can be fabricated, a detailed understanding of their formation mechanism has yet to be fully elucidated. To further understand the formation mechanism in these SNIPS membranes, in situ block copolymer membrane formation that relies on self-assembly of doctor bladed solutions was observed using grazing incidence small-angle X-ray scattering (GISAXS). The evaporation dependent evolution of a disordered to an ordered structure in a film of the triblock terpolymer poly(isoprene-b-styrene-b-4-vinyl pyridine) dissolved in 1,4-dioxane and tetrahydrofuran was observed. The GISAXS pattern of the film exhibited Bragg spots consistent with a bcc structure between evaporation times of 37 s and 58 s, with the most intense Bragg spots occurring after 46 s of evaporation. Projections of the GISAXS patterns were consistent with solution small angle X-ray scattering. Such in situ methods offer the potential to optimize the key parameter of evaporation time in the production of isoporous integral block copolymer membranes.

1. Dorin, R. M.; Marques, D. S.; Sai, H.; Vainio, U.; Phillip, W. A.; Peinemann, K.-V.; Nunes, S. P.; Wiesner, U., Solution Small-Angle X-ray Scattering as a Screening and Predictive Tool in the Fabrication of Asymmetric Block Copolymer Membranes. ACS Macro Letters 2012, 1 (5), 614-617.
2. Peinemann, K. V.; Abetz, V.; Simon, P. F., Asymmetric superstructure formed in a block copolymer via phase separation. Nat Mater 2007, 6 (12), 992-6.
3. Jung, A.; Rangou, S.; Abetz, C.; Filiz, V.; Abetz, V., Structure Formation of Integral Asymmetric Composite Membranes of Polystyrene-block-Poly(2-vinylpyridine) on a Nonwoven. Macromolecular Materials and Engineering 2012, 297 (8), 790-798.
4. Hahn, J.; Filiz, V.; Rangou, S.; Clodt, J.; Jung, A.; Buhr, K.; Abetz, C.; Abetz, V., Structure formation of integral-asymmetric membranes of polystyrene-block-Poly(ethylene oxide). Journal of Polymer Science Part B: Polymer Physics 2013, 51 (4), 281-290.
5. Jung, A.; Filiz, V.; Rangou, S.; Buhr, K.; Merten, P.; Hahn, J.; Clodt, J.; Abetz, C.; Abetz, V., Formation of Integral Asymmetric Membranes of AB Diblock and ABC Triblock Copolymers by Phase Inversion. Macromolecular Rapid Communications 2013, DOI: 10.1002/marc.201200770.
6. Phillip, W. A.; Mika Dorin, R.; Werner, J.; Hoek, E. M. V.; Wiesner, U.; Elimelech, M., Tuning Structure and Properties of Graded Triblock Terpolymer-Based Mesoporous and Hybrid Films. Nano Letters 2011, 11 (7), 2892-2900.
7. Clodt, J. I.; Filiz, V.; Rangou, S.; Buhr, K.; Abetz, C.; Höche, D.; Hahn, J.; Jung, A.; Abetz, V., Double Stimuli-Responsive Isoporous Membranes via Post-Modification of pH-Sensitive Self-Assembled Diblock Copolymer Membranes. Advanced Functional Materials 2012, 23 (6), 731-738.
8. Qiu, X.; Yu, H.; Karunakaran, M.; Pradeep, N.; Nunes, S. P.; Peinemann, K.-V., Selective Separation of Similarly Sized Proteins with Tunable Nanoporous Block Copolymer Membranes. ACS Nano 2012, 7 (1), 768-776.

 

"High-energy x-ray beamline at Cornell High Energy Synchrotron Source for in situ materials studies"

M. K. A. Koker1, J. Y. P. Ko4, D. C. Pagan1,2, D. S. Dale1, J. C. Schuren3, M. P. Miller1,2, E. Fontes1, and J. D. Brock1,4

1 Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY
2 Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY
3 Air Force Research Laboratory, Materials and Manufacturing, Wright Patterson AFB, OH
4 School of Applied and Engineering Physics, Cornell University, Ithaca, NY

Abstract: The F2 beamline at CHESS (Cornell High Energy Synchrotron Source) is currently undergoing an extensive upgrade to facilitate high energy diraction microscopy (HEDM) experiments. This project is a collaborative effort of CHESS, the Air Force Research Laboratory, and the Energy Materials Center at Cornell (emc2). HEDM experiments are ideal for the non-destructive study of mechanical properties and their connection to the microstructure. Part of the project focuses on capabilities needed to perform in situ mechanical loading and heating, namely for investigations of material at extremes. By studying crystal-scale mechanics, a deeper understanding of fundamental grain mechanics, and therefore dramatically improved modeling capabilities, can be achieved. Ideally, such experiments provide insight into the deformation processes occurring in materials in real engineering applicable environments. The beamline will also host a wide variety of other applications such as in operando studies of energy-related materials and high-resolution pair-distribution function studies. Features of the new beamline include a horizontally focused beamsize of  1:2 mm (vertically unfocused,  3 mm), a range of achievable hard x-ray energies (nominally 40{90 keV), an overall increase in ux, the precision mechanical positioning of specimens, the implementation of high resolution area detectors capable of capturing an evolving microstructure, and in situ loading and heating equipment for real-time experiments.

 

"Instantiation of Virtual Polycrystals for Simulation of Deformation Induced Twinning"

Matthew Kasemer
Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY

Abstract: Most high strength structural alloys are polycrystalline materials - meaning they contain regions (grains) that have different crystallographic orientations. The grains can vary widely in size and shape, depending on its processing history. Important design properties, such as stiffness and strength, are sensitive to these features of the microstructure. For example, Ti-6Al-4V, a widely used aerospace alloy, exhibits a wide array of microstructures with attributes that depend strongly on its processing history. Additionally, Ti-6-4 is a two-phase material - meaning it has two co-existing crystalline structures (one hexagonal and the other cubic) present at temperatures below 1000 C. To design machines that are both safer and more economical, better understanding of the structure-properties links in critical, load-bearing materials is paramount. A more fundamental understanding of these links begins with more refined modeling of the microstructure. Higher fidelity microstructural representations can be combined with simulations of the mechanical behavior (finite element analysis) to create tools to emulate experiments in which we can observe responses at the microstructural level through x-ray diffraction. Diffraction provides a non-destructive way of measuring important behavior of specimens throughout different stages of mechanical loading, which in turn lends actual physical insight to the micromechanical behavior of the material, while conventional methods measure.

 

"Spatially Resolved Standing Wave Experiment With Coherent, Monochromatic Gaussian X ray Beams"

Rohit Garg1, Joel D. Brock1,2

1 School of Applied and Engineering Physics, Cornell University
2 Cornell High Energy Synchrotron Source, Cornell University

Abstract: X ray standing wave is an experimental technique used for, among other purposes, vertically resolving atoms adsorbed on crystal surfaces. Here, we focus only on the latter. Since it uses plane waves, due to their infinite transverse extent, it cannot provide horizontal resolution. We propose to extend the standing wave technique to provide horizontal resolution by using coherent, monochromatic gaussian beams. Our proposed technique relies on interaction of curved wavefronts of incident and reflected beams to modulate the fluorescence. We demonstrate our technique using numerical simulations of copper adsorbed on Si 111 crystal surface.

 

"Duplex DNA, RNA and DNA/RNA Hybrid Condensation by Spermine"

Andrea Katz1, Yujie Chen1, Suzette Pabit1, Igor Tolokh2, Alexey Onufriev2, and Lois Pollack1

1Applied and Engineering Physics, Cornell University, Ithaca, NY
2Laboratory for Theoretical and Computational Molecular Biophysics, Virginia Polytechnic Institute and State University, Blacksburg, VA

Abstract: Due to the biological significance of DNA condensation and the potential use of packaged RNA for therapeutics, the behavior of nucleic acids in the presence of condensing agents is a topic of great interest. Following the discovery that double-stranded RNA resists condensation in solutions containing cobalt hexamine [1], we studied short double-stranded DNA, RNA and a DNA/RNA hybrid in the presence of polyamines using UV spectroscopy and small and wide angle x-ray scattering. Polyamine-induced condensation of the nucleic acid constructs will be discussed.

1. L. Li et al., Phys. Rev. Lett. 106, 108101 (2011)

 

"Structural and Biochemical Studies of the CRISPR-associated Protein Cas5a from A.fulgidus"

Qingqiu Huang and Doletha M. E. Szebenyi
MacCHESS, Cornell University, Ithaca, NY 14853

Abstract: Bacteria and archaea acquire resistance to viruses and plasmids by integrating short foreign DNA fragments into their CRISPRs (clustered regularly interspaced short palindromic repeats). These repetitive loci contain genetic records of all prior encounters with foreign transgressors. CRISPR is transcribed and the long primary transcript is processed into a library of short CRISPR-derived RNAs (crRNAs) that contain a unique sequence complementary to a foreign nucleic acid challenger. The E.coli CRISPR-associated complex for antiviral defense (CASCADE) is central in targeting invading DNA, composed of five proteins (CasA, CasB, CasC, CasD and CasE) and CasE-processed crRNA. While the CASCADE of the bacteria B. halodurans is composed of three proteins (Cas5d, Csd1 and Csd2) and Cas5d-processed crRNA. In the archaea A. fulgidus, its CASCADE is composed of four proteins (Csa2, Cas5a, Cas6 and Csa5) and Cas6-processed crRNA. Here we report the structural and functional characterization of Cas5a (aCas5a) from A. fulgidus. Unlike Cas5d from B. halodurans (bCas5d) which has RNase activity, aCas5a does not have nuclease activity. The crystal structure of aCas5a has been solved using SAD method. Though the overall structures of aCas5a and bCas5d are similar, the two structures have significant difference: aCas5a lacks the RNA-binding site found in bCas5d, so it does not have nuclease activity as bCas5d does.

 

"In-Situ Diffraction Measurements of Plastically Deforming Silicon Using High Energy Synchrotron X-Rays"

Darren Pagan, Matthew Miller
Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY

Abstract: Silicon has proven to be an ideal material for studying plasticity mechanisms in crystalline materials due to the availability of large single crystals with low defect concentrations. However, there is still a great deal to learn about the interactions of defects and subsequent misorientation that develops within the bulk of crystalline materials due to the plasticity mechanism of crystallographic slip. Synchrotron radiation can be used as an effective tool to observe misorientations as they develop in silicon single crystals in-situ. The evolving diffracted intensity distributions are directly related to internal structure within the silicon single crystal and the “smearing” that is observed during plastic deformation at high temperatures is consistent with its evolving misorientation distribution. A unique load frame / diffractometer has been built for use in the A2 station at the Cornell High Energy Synchrotron Source (CHESS) which can simulate processing conditions causing plastic deformation while allowing for in-situ interrogation of crystalline samples using high-energy synchrotron x-rays. The experimental set-up and results from an experiment probing silicon as it is compressed at high temperature are presented.

 

"Crystal Structure of the C2A Domain of DOC2a"

Qingqiu Huang and Doletha M. E. Szebenyi
MacCHESS, Cornell University, Ithaca, NY 14853

Abstract: Neurotransmitter release in brain synapses occurs in three kinetically distinct phases: one phase is tightly coupled to action potentials, in which Ca2+ influx triggers rapid synchronous release with a time course of several milliseconds (synchronous); the second phase is immediately following action potentials and can last for tens or hundreds of milliseconds (asynchronous); the third one occurs as stochastic events in the absence of action potentials (spontaneous). It has been found that synchronous release involves the Ca2+ sensors synaptotagmin-1, -2, or -9, which are anchored in the vesicle membrane and contain two cytoplasmic C2 domains that bind phospholipids in a Ca2+-dependent manner and interact with the SNARE complex. Recently, it has been found that DOC2 is required for asynchronous neurotransmitter release (Yao et al., 2011, Cell) and spontaneous neurotransmitter release (Groffen et al., 2010, Science). Similar to synaptotagmin, DOC2 is a Ca2+ sensor containing two tandem C2 domains (designated C2A and C2B) connected by a short linker. Unlike synaptotagmin, DOC2 is a cytoplasmic protein. Here we reported the Ca2+ free crystal structure of the C2A domain of DOCa. The structure consists of a compact β-sandwich formed by two four-stranded β-sheets. It contains all the acidic residues responsible for Ca2+ binding, in agreement with its Ca2+-dependent membrane-binding properties. Similar to other C2 domains, its electrostatic surface is highly basic, for its membrane-binding.

 

"A SAXS Study of the CRISPR associated gene (cas) Csn2 in the presence and absence of Ca2+"

Yujie Chen1, Ki Hyun Nam2, Ailong Ke2, Lois Pollack1

1School of Applied and Engineering Physics and 2The Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14850, USA

Abstract: Small angle X-ray scattering (SAXS) was used to study the solution structures of the E. Faecalis Csn2 protein, a cas gene required for DNA spacer acquisition as part of the CRISPR defense system. Crystallographic study of this protein illustrates a tetrameric ring that facilitates the binding of ds-DNA. Interestingly, monomeric Csn2 is not observed in our solution scattering study. In 2 mM or higher Ca2+ concentrations when Csn2 has strong DNA-binding affinity, our SAXS data agree with the calculated scattering from the crystalline tetramer and consequently elucidate the importance of Ca2+ ions in its ring structure formation and biological function. When the [Ca2+] is lowered or completely chelated by EGTA, a conformational change followed by higher order oligomerization was observed through direct comparison of the normalized scattering profiles. Analysis of the SAXS data by Rg and P(r) analyses and shape reconstruction shows that the conformational change is consistent with a pore elongation in 1.5 mM Ca2+. These biochemical and biophysical results lead us to propose a physiological model for the functioning of the Csn2 protein upon phage invasion.

 

"CESR & CHESS UNDULATOR UPGRADE*"

A. Temnykh and A. Lyndaker for CESR & CHESS Operating Groups
LEPP-CHESS Laboratory, Cornell University, Ithaca, NY, 14853, USA

 

"Upgrades to CHESS Beamlines for undulator Operation"

Karl Smolenski, Don Bilderback , Ernie Fontes, Rong Huang, Aaron Lyndaker, Jim Savino, Sasha Temnykh
Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, 14853, USA

Abstract: Over the next two years, the wigglers that provide beam to CHESS A, G, and F lines will be replaced with undulators currently under development and testing. This, in combination with upgrades to CESR, will provide greatly enhanced flux (a factor of 40) and brightness (a factor of 100) to these beamlines. In order to accommodate these more intense beams, the optical elements of these beamlines will be replaced with state of the art commercial optics. In 2014 two canted short (1.7m) undulators will be installed in CHESS west allowing independent operation of each station on A-line and G-line (fed by the same undulators). Cryocooled silicon monochromators will be used on A-line, while multilayer optics will be maintained on G-line with internal cooling if required. Following in 2015, a second set of undulators will be installed on F-line for F1 and F2. The flexibility of the undulator design allows us to tailor its design to compliment the high energy needs of the F2 station and its Laue based high energy monochromator.

 

"Rocking Curve Mapping of defects in large Lab-grown Single Crystal Diamonds plates"

Alvarado TARUN1#, Lin LIN1, Sian Jun LEE1, SiewYuen YEE1, Siwei XIAO1, Chuan Ming YAP1, BaoFeng ZHANG1, Komal RATHORE1, Kenneth David FINKELSTEIN2, Donald BILDERBACK2, D.S. MISRA1

1IIa Technologies Pte Ltd, Singapore
2CHESS, Cornell University, Ithaca, United States
#Corresponding author: ATarun@2a-tech.com.sg

Abstract: Mapping the crystalline quality of the entire surface of 5mm x 5mm-sized diamond crystal plate with arc second angular resolution is of great interest in the growing field of diamond technology and in particular for the diamond radiation detectors and reflectors plates in Synchrotron machines. Using the Cornell High Energy Synchrotron Source equipped with CCD detectors, we obtained rocking curves from a total of 25, (001)-oriented single crystal diamonds (SCD) plates grown under high pressure high temperature (HPHT) and plasma enhanced chemical vapour deposition (CVD). The average full width at half maximum (FWHM) for the HPHT grown crystals is 13.1 mRad and were narrower than CVD grown (type IIa) SCD crystal plates. For type IIa diamonds, we found that the average FWHM of 10 plates of light-shades is 29.2 mRad, which are generally narrower than the average FWHM of 49.9 mRad of 10 plates of dark-shades SCD plates. Using birefringence microscopy, it was shown that highly stressed areas show huge broadening in the full-width half-maximum (FWHM) of the rocking curve. This broadening was attributed to bending, tilts, and twinning during crystal growth as well as residual strain at the surface induced by polishing.

We note that the average FWHM of the rocking curves correlate with the C-H impurities measured using FTIR and the density of nitrogen vacancies (NV) obtained from Raman/PL spectroscopy. Broadening of FWHM from lattice imperfections due to impurities are more subtle compared to lattice parameter variations caused by tilts, bending and stress points. This spatially resolved crystal quality of diamond has vital role on the performance of diamonds in wide range of applications

 

"G-Line High Precision Optical Table & Gantry System"

Matt Popov3, Arthur Woll1, Joel D. Brock1,2, A Lyndaker1, Eric Van Every3, Howie Joress1, Alex Deyhim3

1Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY
2School of Applied and Engineering Physics, Cornell University, Ithaca, NY
3ADC USA, Inc. Lansing, NY www.adc9001.com

In this poster we present two independent high precision motion systems that were designed for the G-Line at CHESS. The G-Line station make use of radiation from the same 49-pole wiggler that feeds the A1 and A2 hutches at CHESS West; the 5.3 GeV electron beam circulates counterclockwise and produces X-rays for A1 and A2, while the positron beam circulates clockwise and feeds G1, G2 and G3. The high intensity available at the G3 station is used by a wide variety of research groups from Cornell University and others around the world, to study the structure and dynamics of matter at the atomic scale. The G3 station generally operates from 8 to 12 keV, and combines horizontal and vertical focusing with synthetic multilayer monochromator pairs to deliver upwards of 5x1013 photons/sec/mm2, at the sample.

The first system is the optical table, a 3 axis motion. The linear motion is supported by THK HSR35 guide rails and bearings. A preloaded 20x5 mm ball screw coupled to a NEMA 23 motor and a 10:1 gear reduction allows the unit to have a 2.5 µm resolution. The vertical motion consists of 4 ADC 5kN Utility Jacks that are geared to be driven off of one motor. The one motor approach is preferred to avoid the potential binding of the jacks that is common with driving each jack individually. The rotary motion for this optical table provides a full 360º rotation, and is equipped with fully adjustable limit switches to set travel limits as necessary. The second system consists of a Gantry System with 5 motions, including 3 linear slides providing X, Y and Z translations, and 2 rotary stages providing the pitch and yaw rotations. The members of the frame are steel tubes which are welded to steel plates that contain slotted holes for alignment of the unit. The frame is designed to be modular in construction so that it can be assembled efficiently. Maximum rigidity is assured through the use of preloaded linear guide rails. Each slide also features two fully adjustable, normally closed, limit switches to define the extents of travel. These stages not only give an exceptionally high running accuracy, but allow for large radial and thrust loads as well. Each stage is driven by a precision ground worm gear set and a high resolution, high torque stepper motor. Backlash is reduced by employing a flexure style shimming technique to preload the worm and worm wheel.

 

"Area detector development at Cornell"

Katherine S. Green, Hugh T. Philipp, Darol Chamberlain, Prafull Purohit, Mark W. Tate, and Sol M. Gruner
Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY

Abstract: We present an overview of the work done at Cornell to develop area detectors that will meet and anticipate the needs of the x-ray science community. Our focus is on area detectors based on direct detection of x-rays in a silicon sensor. Direct conversion of absorbed x-rays to charge carriers in silicon provides high-fidelity measurements of total absorbed x-ray energy, and high-resolution spatial data. Pixel array detectors (PADs) allow for a highly flexible detector that is made by coupling commercially fabricated CMOS with high-quality, pixelated silicon diode sensors. Using commercial CMOS processes allows for efficient and custom processing of x-ray generated signal. PADs developed in our lab have been used in experiments at CHESS and the APS, with applications ranging from coherent diffractive imaging to time-resolved studies of materials science samples. Direct-detection CCDs combine the high spatial resolution offered by direct conversion in silicon with the smaller pixel sizes available in CCD technology. A prototype direct-detection CCD has been used to successfully collect protein crystallography data at CHESS beamline F1.

 

"Thermal Processing of Binary Nanoparticle Superlattices"

Benjamin Treml
Chemical Engineering, Cornell University, Ithaca, NY

Abstract: Binary nanoparticle superlattices (BNSLs) make use of progress in the synthesis of colloidal nanoparticles with size dependent properties to create new designer materials. Like conventional table salt, made from Na and Cl atoms but with its own properties, BNSL’s exhibit novel properties above and beyond the properties of the nanoparticle building blocks1. We use GISAXS to determine the structure of the BNSLs and then investigate the structural evolution during equilibrium and non-equilibrium thermal processing. In situ GISAXS at the CHESS D1 station allows real time observation of the structural evolution with increasing annealing temperature. We also examine structural changes due to Laser Spike Annealing (LSA) and find that non-equilibrium processing methods allow for processing at higher temperatures while maintaining superlattice structure. LSA shows promise as a processing technique for structural control and thermal annealing of both single and multicomponent nanoparticle superlattices.

1. Dong, A.; Chen, J.; Vora, P. M.; Kikkawa, J. M.; Murray, C. B. Binary Nanocrystal Superlattice Membranes Self-Assembled At The Liquid–Air Interface. Nature 2010, 466, 474-477.

 

"Energy and Power in Li-Ion Battery Through Synchronized Process and Crystal Engineering"

Shailesh Upreti1, Kira Hicks2 and Robert Dobbs1

1Primet Precision Materials, Ithaca, NY 14850
2Cornell University, Ithaca, NY 14850

Abstract: Throughout the history of materials science, existing self assembled natural and synthetic materials have often provided inspiration for future materials. A central challenge in applied materials science is the development of high-quality materials with useful properties that can be efficiently and consistently manufactured on a large scale. Although sound progress is being made, the link between crystallographic engineering and process engineering still needs to be strengthened in order to produce solids with desired properties more effectively. It has also been observed that the same material can behave very differently in different structural forms, such as bulk solids and nano-scale powders. Therefore, structure and process engineering play an important role in tuning a material’s desired properties, especially in the battery industry. More effective design and prediction of new crystal structures for cathode and anode materials may be achieved by using a posteriori analysis of similar existing structures. This can help with the identification of relevant crystallographic factors, which will in turn aid in the development of future materials. This process may serve as a blueprint for both crystal engineering and particle engineering.

The primary objective of the current presentation is to demonstrate a fundamental understanding of crystal engineering, and how it can be applied to particle engineering in order to continually develop better performing battery materials. An especially important tool in this process is systematic, real-time materials analysis using synchrotron x-ray beams.

 

"X-ray Crystal Structure and Biophysical Analysis of a Class 2 PreQ1 Riboswitch"

Joseph A. Liberman, Mohammad Salim, Jolanta Krucinska, Joseph E. Wedekind*
Department of Biochemistry & Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave Box 712, Rochester NY 14642 USA

†Funded in part by NIH grants GM063162 and RR026501 to J.E.W.
*Correspondence: joseph.wedekind@rochester.edu

Abstract: Riboswitches are cis-acting RNAs that regulate gene expression via ligand binding. Typically located in the 5´-leader sequences of bacterial genes, riboswitches have potential as novel antimicrobial targets. Of special interest are riboswitches that bind ligands that are unique to the bacterial metabolome. One such molecule is preQ1, a pyrrolopyrimidine that interacts with a cognate riboswitch in >29 bacterial species including several human pathogens. To date two classes of preQ1 riboswitches (termed preQ1-I and preQ1-II) have been described but structural information has been described only for class 1. Here we present the structure of a 77-mer, class 2 preQ1 riboswitch in the ligand-bound state at 2.3 Å resolution. The structure was solved by SAD phasing from co-crystalized, site-bound Cs+ ions. The preQ1-II riboswitch differs completely from preQ1-I riboswitches in terms of its fold and mode of ligand recognition. The preQ1-II architecture adopts a “J”-like conformation in which helices P1, P2 and P3 adopt a 75 Å co-axial stack. The topology is that of an H-type pseudoknot in which the entire ribosome-binding site (RBS) is sequestered in helix P3, which abuts the preQ1-binding pocket located at the confluence of the P2-P3-P4 helical junction. Non-Watson-Crick readout of preQ1 occurs within one tier of a three-layer U•A-U major-groove base triple; we validated this mode of ligand recognition using isothermal titration calorimetry. Notably, the preQ1-II U•A-U major-groove base triples are structurally homologous to those of human telomerase RNA (rmsd 1.46 Å) in which disruption of any base in the layer equivalent to that which binds preQ1 was shown to cause global hTR destabilization. By analogy our solution analysis by in-line probing showed that base-triple formation and adjacent RBS sequestration depends on ligand binding, thus providing a plausible mechanism for preQ1-dependent translational regulation. The results are broadly applicable to other riboswitches that control gene regulation at the level of translation, and expand the known repertoire of ligand-binding modes used by functional RNAs.

 

"Collecting sub-second images @ MacCHESS"

David J. Schuller
MacCHESS, Cornell University, Ithaca, NY

Abstract: Single crystal macromolecular diffraction at MacCHESS usually involves rotating a sample crystal through an angle while diffracting monochromatic X-rays from it (Bragg scattering). A set of such exposures cover the necessary region of reciprocal space to enable Fourier analysis. A typical single exposure may cover 0.3 - 1.0 degrees and last 1-120 seconds. Recent experiments with diffuse scattering led to the revelation that the equipment at MacCHESS performs poorly for exposures much less than one second. The routines controlling the X-ray shutter and rotation motor have been examined and reworked for better chronological control and more uniform angular coverage. As proof of principle, a set of data consisting of 30 millisecond exposures was collected and processed, and the results compared to data sets of longer exposures.

 

"The CAPERα UHM Provides a Potential Means for Alternative Splice Site Regulation"

Sarah Loerch1, Valerie Manceau2, Alexandre Maucuer2, Michael R. Green2 and Clara L. Kielkopf1

1Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, NY
2HHMI and Program in Gene Expression, University of Massachusetts Medical School, Worcester, MA

Abstract: CAPERα is of major medical interest as it plays a crucial role in tumor growth and angiogenesis in Ewing sarcoma1 and other cancers. In its physiological function, CAPERα is responsible for the alternative splicing of genes under the control of certain steroid receptor promoters. However, the molecular mechanisms and pathways of splice site regulation by CAPERα remain unknown. CAPERα contains a putative U2AF homology motif (UHM), a domain frequently found in early 3' splice site recognition factors. UHMs recognize a key tryptophan in short sequences termed "U2AF ligand motifs" (ULM)2. We determined structures of the CAPERα UHM bound to a prototypical ULM at 1.74 Å resolution, and for comparison, in the absence of ligand at 2.20 Å resolution. The binding pocket for the ULM key tryptophan appears pre-formed in the apo-structure (rmsd 0.667 Å). The UHM/ULM-interactions authenticate CAPERα as a bona fide member of the UHM-family of proteins and suggest possible regulation of UHM-interactions by phosphorylation within the ULM. Furthermore, we identified the spliceosome subunit SF3b155 as a relevant binding partner for CAPERα. Because SF3b155 also interacts with UHMs of constitutive splicing factors, this work demonstrates a new interface for the regulation of alternative and constitutive pre-mRNA splicing.

1 G. Huang, Z. Zhou, H. Wang, E.S. Kleinerman (2011) Cancer 118(8):2106-2116.
2 C.L. Kielkopf, S. Lucke, M.R. Green, U2AF homology motifs: protein recognition in the RRM world. Genes Dev 2004, 18 (13), 1513-1526.

 

"Effect of Changes of the Surface Structure of SrTiO3 on the Catalysis of Photo-Assisted Water Splitting"

Xin Huang,1,2 Manuel Plaza,1,2 Joaquín Rodríguez-López,3 Nicole L. Ritzert,4 Mei Shen,3 J. Y. Peter Ko,1,2 Darrel G. Schlom,1,5 Héctor D. Abruña,1,2 and Joel D. Brock1,2,6

1Energy Materials Center at Cornell, Cornell University, Ithaca NY 14850, USA
2School of Applied and Engineering Physics, Cornell University, Ithaca NY 14850, USA
3Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
4Department of Chemistry and Chemical Biology, Cornell University, Ithaca NY 14850, USA
5Materials Science and Engineering, Cornell University, Ithaca NY 14850, USA
6Cornell High Energy Synchrotron Source, Cornell University, Ithaca NY 14850, USA

Abstract: Although many experiments and models have been conducted and proposed about adjusting the bulk and electronic structure of electrode materials to optimize the catalytic properties [1,2], much less has been known about the surface transformations during the photo catalytic reaction. Moreover, the contribution of the surface structure to the catalytic properties remains unknown.

In this poster, we report the evolution of the surface of the SrTiO3 (001) during photo-assisted electrocatalysis, and the surface-dependent activity towards the water splitting at open circuit potential. By means of in situ high-energy X-ray reflectivity, we calculate the electron density of the SrTiO3 electrode surface during electrochemical reaction. The photo catalytic properties have been studied with in situ scanning electrochemical microscopy. “Training” the surface by biasing to potentials where photo electrochemical oxygen evolution occurs in basic medium, both irreversibly alters the surface structure to more stable surface structure and increases three times the water splitting activity at open circuit.

Reference:
[1] Suntivich, J.; May, K.J.; Gasteiger, H.A.; Goodenough, J.B.; Shao-Horn, Y. Science 2011, 334, 1383-1385.
[2] Kudo, A.; Miseki, Y. Chem. Soc. Rev. 2009, 38, 253–278

 

"X-RAY DIFFRACTION OF ORGANIC CATHODE MATERIALS IN LITHIUM-ION BATTERIES"

Katie Silberstein, Michael Lowe, Weidong Zhou, Jie Gao, Héctor Abruña
School of Chemistry and Chemical Biology, Cornell University, Ithaca NY

Abstract: The Abruña research group has developed and characterized numerous promising materials for battery and fuel cell applications. In the present context, we focus on organic-based battery materials and intend to investigate how molecular structure relates to bulk characteristics of the materials of interest, with emphasis on charge storage. Conventional lithium-ion batteries employ inorganic oxides (e.g. LiCoO2) and graphite (LiC6) as cathode and anode electrodes, respectively. The charge/discharge process involves (de)/intercalation events which are known to be kinetically slow, resulting in low rates of charge and discharge. An alternative, yet relatively unexplored, approach is the use of electroactive organic molecules (in place of the metal oxide) as the cathode in a lithium-ion battery (LIB). Through computational design and screening, combined with synthesis, organic molecules can be tuned over a broad parameter space to yield materials that can exchange multiple electrons per formula unit, leading to high gravimetric capacities. In addition, the formal potentials can be tuned so that theoretical energy densities in excess of 1,500 Wh/kg are possible.

To date, the interactions of lithium ions with these organic materials within a working cell are not well understood. How is the lithium incorporated? Does it intercalate between layers within microcrystals? Does it ionically coordinate to electronegative moieties? By monitoring structural changes of the organic compounds via X-ray diffraction as a function of the state of charge, we can begin to elucidate the molecular mechanism of lithium incorporation that leads to charge storage. Our test system includes anthraquinone and two derivatives with different electron-withdrawing groups. A deeper physical understanding of these materials will allow for a more rational design and, ultimately, more efficient devices.

 

"What's in the Eye of the Lamprey? A Look at Five Sea Lamprey Lenses, from A(u) to Z(n)"

Karin E. Limburg1#, Thomas Evans1, Aude Lochet2 and Darren Dale3

1Department of Environmental and Forest Biology, SUNY College of Environmental Science and Forestry, Syracuse, NY 13210
2The Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, Vermont 05401 USA
3Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY 14853
#corresponding author KLimburg@esf.edu

Abstract: Sea lamprey (Petromyzon marinus) are among the most primitive of extant fishes. As such, they lack true otoliths, and instead have primitive hearing/balance structures called statoliths. Research into whether statoliths can be used to determine the provenance of adult lampreys has shown that these organs transform chemically when the fish metamorphoses from its larval, stream-bottom-dwelling form to its adult, parasitic form. However, in fishes, eye lenses are permanent structures that retain elemental concentrations in a manner similar to otoliths, and might prove to be superior to statoliths in terms of linking adult lampreys back to their natal streams.

We examined lamprey eye lenses from 5 newly transformed sea lampreys (larva to adult form) from Mount Hope Brook that drains into southern Lake Champlain. Lenses were analyzed with scanning x-ray fluorescence microscopy (SXFM) at the F3 beamline at CHESS. All 5 lenses showed uptake of the same dozen elements, albeit with some spatial variation and differences in concentration. However, the “signature” was very clear and dominated by Cu, Hg, Rb, Se, and Zn. We conclude that the method shows great promise as a forensic tool to determine the natal origins of sea lamprey.

 

"Thermal stable Si nanocrystal superlattice drop-cast from colloidal dispersion"

Yixuan Yu[a], Christian A. Bosoy[a], Colin M. Hessel[a], Detlef-M. Smilgies[b], and Brian A. Korgel[a]

[a] Department of Chemical Engineering, Texas Materials Institute, and Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, Texas 78712-1062, USA
[b] Cornell High Energy Synchrotron Source (CHESS) Cornell University, Ithaca, New York 14853, USA

Abstract: Si is one of the most commercially important semiconductors. Si nanocrystals can exhibit bright, size-tunable, visible photoluminescence and electroluminescence, which make them especially interesting for optoelectronic applications requiring light emission. Si quantum dots are also being explored as a laser source. Photovoltaic devices utilizing Si quantum dots have also been proposed because of their size-tunable optical absorption edge, much higher absorption coefficient and the potential for multi-exciton generation (MEG). Most collections of Si nanocrystals studied to date have been disordered with a significant size distribution. We obtained FCC superlattices with size-selected organic capped Si nanocrystal by drop casting. The superlattice structure was determined to FCC through grazing incidence small angle X-ray scattering (GISAXS). The superlattice was found to be stable up to 280 oC, which is much more thermally stable than other colloidal nanocrystals, like Au, Ag, or PbSe.

 

"CHESS Rocking Curve Measurements of Thin Diamonds for the GlueX Experiment"

Alex Barnes
University of Connecticut

Abstract: The GlueX experiment at the Thomas Jefferson National Lab in Newport News, Virginia is a photonuclear experiment designed to explore the excited gluonic bonds between quarks. The excitation of the bonds is induced by the absorption of a polarized high energy photon by a proton in a liquid hydrogen target. To create a well collimated polarized photon beam, coherent bremsstrahlung radiation was chosen. A 12GeV electron beam will pass through a 20μm thick diamond wafer and undergo the bremsstrahlung process. The spread of photon production is not only a function of the thickness of diamond, but also of its planarity. The lattice structure of an ideal diamond makes it a good choice, however modern machining techniques tend to leave the diamonds curved and stressed resulting in a wide bremsstrahlung peak. The collaboration group at UConn has developed a laser ablation process to create 20μm CVD diamond radiators free from strain and warping. Rocking curve measurements taken at CHESS and surface profiles are presented which demonstrate that this process results in diamond radiators which meet the GlueX criteria for thickness, flatness, and crystal mosaic spread.

 

"Artifacts in grating interferometry data"

Robin M Baur, Darren S Dale, Sol M Gruner
Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY

Abstract: Since grating interferometry data have sinusoidal character, it is natural to want to use the Discrete Fourier Transform to extract the sinusoid parameters. However, in the presence of thermal distortion of the interferometer or drift in beamline optics, the DFT tends to recover the parameters incorrectly, in such a way that "shadows" of the original moiré fringes remain in the processed image. Markov chain Monte Carlo methods can be used to correctly recover dataset parameters in situations where the DFT fails catastrophically.

 

"Identification of good conditions for solvent vapor annealing of block copolymer thin films"

A. Sepe1, D. Posselt2, K. Swiatek2, S. Jaksch1, R. Steinacher1, J. Zhang1, J. Perlich3, D.-M. Smilgies4 and C. M. Papadakis1

1Technische Universität München, Physik-Department, Physik weicher Materie, James-Franck-Str. 1, 85748 Garching, Germany
2IMFUFA, Department of Science, Systems and Models, Roskilde University, Denmark
3HASYLAB at DESY, Notkestr. 85, 22603 Hamburg, Germany
4Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, USA

Abstract: Nanostructured block copolymer thin films are used as templates for inorganic nanostructures, where a perfect alignment of the structures is mandatory for their technological application. Solvent vapor annealing has emerged as a promising and highly versatile method to improve ordering in nanostructured thin film. We show how alignment of nanostructures in a thin block copolymer film can be controlled and improved by carefully selecting solvent annealing conditions during swelling and during drying. The model system studied are thin films of lamellae-forming poly(styrene-b-butadiene) (P(S-b-B)) in cyclohexane vapor, a solvent slightly selective for PB. The dry film features lamellae parallel to the substrate surface with a number of orientational defects. We have developed a protocol for solvent annealing, where the control parameters are the rates of swelling and drying as well as the maximum degree of swelling of the film. The structural changes during swelling and drying are monitored in-situ using time-resolved grazing-incidence small-angle X-ray scattering (GISAXS) and ex-situ using X-ray reflectometry. For a sufficiently high maximum degree of swelling, good alignment of the lamellar nanostructure is achieved. This alignment is improved during drying, provided the rate of drying is sufficiently low. Thus, to obtain well-ordered lamellar nanostructures in block copolymer thin films, it is important to cross the glass transition of both blocks, but not the order-disorder transition, that the film is dried sufficiently slowly. Our study opens the route to obtain and control well-ordered block copolymer thin films, which appears to be widely applicable to post-processing of soft materials after deposition.

 

"Photo-Induced Disorder in Block Copolymer/Additive Composite Films for Hierarchical Pattern Formation"

Li Yao, James Watkins
Department of Polymer Science and Engineering, University of Massachusetts Amherst

Abstract: Ordered structures can be generated through selective hydrogen bonding between organic or nanoparticle additives and one block of weakly segregated block copolymers to increase the segregation strength in hybrid materials. Here, we report the use of enantiopure tartaric acid as the additive to dramatically improve ordering in poly(ethylene oxide-block-tert-butyl acrylate) (PEO-b-PtBA) copolymers. TEM, atomic force microscopy (AFM) and X-ray scattering were used to study the phase behavior and morphologies within both bulk and thin films. With the addition of a photo acid generator, photo-induced disorder in PEO-b-PtBA/tartaric acid composite system can be achieved upon UV exposure to deprotect PtBA block to yield poly(acrylic acid) (PAA), which is phase-miscible with PEO. Due to the strong interaction of tartaric acid with both blocks, the system undergoes a disordering transition within seconds during a post-exposure baking, which can be tracked by GISAXS to optimize the conditions. With the assistance of trace-amounts of base quencher, high resolution, hierarchical patterns of sub-micron regions of ordered and disordered domains were achieved in thin films through area-selective UV exposure using a photo-mask.

 

Christian Ocier
Materials Science and Engineering, Cornell University, Ithaca, NY

Abstract: Advances in colloidal chemistry have enabled the synthesis of anisotropic nanostructures like rods with exquisite control over their aspect ratios. The quality of these materials facilitates their organization into ordered superlattices that exhibit unique properties and functionalities depending on the material composition and assembly structure. Previously, we demonstrated that solvent vapor annealing can be employed towards preparing ordered superlattices of isotropic nanocrystals. In this study, we investigate how the same technique can be used to assemble films of core/shell cadmium selenide/cadmium sulfide nanorods into vertically oriented superlattices by controlling the cell's solvent composition and inlet gas temperature. The structural evolution of these materials are monitored by in-situ GISAXS and GIWAXS, whereas their optical properties are recorded using in-situ UV-Vis spectrometer. Ex-situ optical experiments were conducted to confirm the orientation-dependence of the optical properties and to define our materal's structure-property relationships. Our study indicates that solvent vapor annealing can be used as a robust technique for assembling large-scale arrays of nanorods into superlattices with orientation-dependent functionalities.

 

"Fabrication of Spoked Channel Arrays for 3D micro-Xray Fluorescence"

David Agyeman-budu
Cornell University, Ithaca, NY

 

"The Hard X-ray Polarimeter X-Calibur Astrophysical Motivation and Performance"

Kenneth Finkelstein
Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY

 

"X-ray Emission Collected Using a Novel Energy Dispersion Method"

Kenneth Finkelstein
Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY

 

"Advances in BioSAXS at MacCHESS"

Richard Gillilan
MacCHESS, Cornell University, Ithaca, NY

 

"In-plane anisotropy of organic semiconductors revealed by in situ structural monitoring in doctor blade casting"

Ruipeng Li
Cornell University, Ithaca, NY

 

"What's New at MacCHESS"

Marian Szebenyi
MacCHESS, Cornell University, Ithaca, NY

 

"High pressure SAXS/WAXS/Spectroscopy at CHESS (B1): opening new dimension of nanocrystal supercrystals"

Zhongwu Wang
Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY

 

"Graphene as a protein crystal mounting method for reducing background scatter"

Jennifer Wierman
Biophysics, Cornell University, Ithaca, NY