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Atomic holography
Sub-Angstrom resolution images of atomic structure can be obtained from the holographic interference patterns generated by photoelectrons or core x-rays emitted from within a locally coherent environment. Not that we really understand what the heck we're really talking about, either, but you can peruse these abstracts from our long list of publications, and even download some of the articles themselves in .pdf format from these links to the American Physical Society. These images of atoms represent the long-awaited direct probe of solid phase structures anticipated immediately following the original discovery of the wave nature of electrons and x-rays about a century ago. But then again this "new" holographic method has since been surpassed by other less-direct methods that have been developed in the interim (a century is a long time to wait), refined whilst atomic holography finally came to fruition within the past fifteen years. Still, the "proof-of-principle" demonstrated by obtaining actual crude atomic images from direct transformation of holographic photoelectron and x-ray interference patterns was a neat trick, and in the near future atomic holography may actually answer questions about certain phenomena that defy and elude historically more tried-and-true traditional probes of atomic structure.

Preliminary experimental holographic images of iron atoms in hematite (Fe2O3), in (a) vertical and (b) horizontal views.
Publications and Presentations
(Articles that have links to .html abstracts and/or are downloadable in .pdf format are indicated below.)

Inter-Nuclear PE Graphs: Beyond Balancing Reaction Equations and Calculating Mass Defects in Analyzing Fusion, Fission, and (alpha) Decay
P. M. Len
Talk Presented at the Spring 2003 Meeting of the Nevada/Northern California Chapter of the American Association of Physics Teachers, Sonoma State University

Holographic Images of Atoms: Past Achievements and Future Prospects
P. M. Len
Department of Physics and Astronomy Colloquium Talk (March 6, 2003), California State University-Sacramento

Breathing-synchronized radiotherapy program at the University of California Davis Cancer Center
H. D. Kubo, P. M. Len, S.-I. Minohara, H. Mostafavi
Medical Physics, 27, 346 (2000)

Holographic atomic images from surface and bulk W(110) photoelectron diffraction data
P. M. Len, J. D. Denlinger, E. Rotenberg, S. D. Kevan, B. P. Tonner, Y. Chen, M. A. Van Hove, and C. S. Fadley
Phys. Rev. B, 59, 5857 (1999)

Multiple energy x-ray holography: Incident-radiation polarization effects
P. M. Len, T. Gog, D. Novikov, R. A. Eisenhower, G. Materlik, and C. S. Fadley
Phys. Rev. B 56, 1529 (1997)

Atomic holography with electrons and x-rays
P. M. Len, C. S. Fadley, and G. Materlik
X-ray and Inner Shell Processes: 17th International Conference, AIP Conf. Proc. No. 389, edited by R. L. Johnson, H. Schmidt-Boeckering, and B. F. Sonntag (AIP, New York, 1997), p.295

X-ray fluorescence holography and multiple-energy x-ray holography: A critical comparison of atomic images
P. M. Len, T. Gog, G. Materlik, and C. S. Fadley
Phys. Rev. B 55, R3323 (1997)

X-ray holography with atomic resolution: Trying to make it work
T. Gog, R.-H. Menk, F. Arfelli, P. M. Len, C. S. Fadley, and G. Materlik
Synch. Rad. News 9, 30 (1996)

Holography with x-rays
C. S. Fadley and P. M. Len
Nature 380, 27 (1996)

Multiple-energy x-ray holography: Atomic images of hematite (Fe2O3)
T. Gog, P. M. Len, G. Materlik, D. Bahr, C. Sanchez-Hanke, and C. S. Fadley
Phys. Rev. Lett. 76, 3132 (1996)

Optimization of k-space sampling in atomic imaging by electron holography
P. M. Len, S. Thevuthasan, A. P. Kaduwela, M. A. Van Hove, and C. S. Fadley
Surf. Sci. 365, 535 (1996)

Photoelectron holography: Prospects and limitations of direct methods
P. M. Len, F. Zhang, S. Thevuthasan, A. P. Kaduwela, M. A. Van Hove, and C. S. Fadley
J. Electron Spectrosc. Relat. Phenom. 76, 351 (1995); 85, 145 (1997)

Atomic imaging by x-ray-fluorescence holography and electron-emission holography: A comparative theoretical study
P. M. Len, S. Thevuthasan, C. S. Fadley, A. P. Kaduwela, and M. A. Van Hove
Phys. Rev. B 50, 11275, (1994)

Images, characters, and website copyright © 2003 Patrick M. Len