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John C.H. Spence
Regents' Professor
Dept. of Physics & Astronomy
Arizona State University
Research Interests:
The Spence group undertakes experiments in condensed matter physics based around the use of electron beams for imaging, spectroscopy and diffraction. This includes the use of the facilities of the electron microscope center, together with new instruments we have built or modified ourselves, such as the "MIDAS" 100 kV field-emission STEM, our Scanning Atom Probe, which integrates a time-of-flight spectrometer with an STM, and a new low-temperature STM. The MIDAS instrument has been modified for lithography at the Angstrom level, allowing us to form patterned arrays of "Nano-rings", whose optical and superconducting properties we are investigating. Our quantitative convergent beam (QCBED) research allows us to directly image the chemical bonds which bind atoms together in solids. This experimental work is accompanied by band-structure calculations, which allow us to test the latest many-electron approximations used against experiments. This research includes the strongly correlated transition metal "Mott insulator" oxides and the collosal magnetoresistance (CMR) effect. Our organic materials work develops new methods for imaging thin organic films using energy-filtered electron diffraction at liquid helium temperatures. Theoretical work continues on the inversion problem of multiple scattering, and experimental research is supported on the use of coherent sub-nanometer electron probes for the study of dislocation core structures, and on electron channelling effects on X-ray production (ALCHEMI). We are also involved at Lawrence Berkeley Laboratory in reseach into lensless imaging methods, and are users of beamlines there for the CMR research. This work is supported by grants from NSF and ARO.
New York Times, Sept. 7
(enlarged image), for a simple
explanation of these direct
images of chemical bonds
electron clouds see here.



Electronic Orbitals in Cuprite
(J.M. Zuo, M. Kim, J.C.H.
Spence)



Highlight on title page of
Nature Physics Portal,
"Zooming in on Atoms", June
11, 2001. (free registration
may be required)
Schedule of Lectures:
"Diffraction from a Beam of Laser-Aligned Proteins, and some Cavendish History" "Diffractive (Lensless) Imaging with Neutrons, X-rays and Electrons" "Diffraction Physics, New Microscopies and Other Interesting Stuff"
Monday, November 7
3:30pm - Reception
4:00pm - Lecture

Schwartz Auditorium
Rockefeller Hall
Tuesday, November 8
11:45pm - Lunch
12:30pm - Lecture

G10 Biotechnology
Thursday, Novemeber 10
4:00pm - Reception
4:30pm - Lecture

700 Clark Hall