University of Tennessee Physics

Dr. Jon Levin

Professor
Ph.D., University of Oregon, 1986

Office: M-103 Nielsen
Phone: 865-974-8705
Fax: 865-974-7843
jlevin@utk.edu

ATOMIC PHYSICS

Atomic physics with synchrotron radiation

My research is focussed on studies of the interactions between single atoms and x rays. Modern synchrotron-radiation sources permit 'dissection' of the atom with almost surgical precision. The resultant ion charge is strongly dependent on the photon energy, and can provide information about the mechanisms by which atomic reorganization proceeds. Many phenomena are found to be important, including excitation of an electron to an unoccupied, but bound, atomic level; electron-electron correlation; recapture of an escaping electron by the residual ion; and vacancy multiplication, in which an inner-shell vacancy 'bubbles' up to the outer shells producing ever greater degrees of ionization on the way.

A single photon can directly remove, or ionize, only a single electron from an atom. Nonetheless, a single hard x ray interacting with a helium atom can, on occasion, produce a doubly charged ion as a result of correlation between the two electrons. The primary ionization mechanism varies smoothly from photoionization at low energies to Compton ionization at high energies, with the amount of electron-electron correlation a strong function of both energy and ionization mechanism. Studies of double ionization in helium are a central component of my research.

In interactions with a heavy atom, a single energetic x ray can produce a broad distribution of ion charge states, ranging in xenon, e.g., from singly to thirteen-times-ionized xenon. This broad distribution is the result of a complex reorganization undergone by the atom following creation of an inner-shell vacancy. The many paths by which this reorganization can proceed depends strongly on photon energy and is one subject of my ongoing research.

These investigations are performed by time-of-flight and coincidence techniques at the National Synchrotron Light Source near New York, the Advanced Light Source in Berkeley, the European Synchrotron Radiation Facility in Grenoble, and the Advanced Photon Source near Chicago, in collaboration with colleagues from UT and other institutions.

Brief Vita

Professor Jon C. Levin received his B.A. in economics in 1976 from Stanford University, and Ph.D. in physics in 1986 from the University of Oregon. Thereafter, he was a postdoctoral research associate at Oak Ridge National Laboratory, and a staff physicist in the Quantum Metrology Division of the National Institute of Standards and Technology before joining the faculty at the University of Tennessee in 1993. He is a member of the American Physical Society and the American Association of Physics Teachers

Selected Publications

  1. R. Wehlitz, R. Hentges, G. Prumper, A. Farhat, T. Buslaps, N. Berrah, J. C. Levin, I. A. Sellin, and U. Becker, "Compton Double-to-Single Ionization Ratio of Helium at 57 keV," Phys. Rev. A, June, 1996, in press.
  2. Jon C. Levin, G. Bradley Armen, and Ivan A. Sellin, "Photoionization and Compton Double Ionization of helium from Threshold to 20 keV," Phys. Rev. Lett. 76, 1220 (1996).
  3. G. Bradley Armen, Jon C. Levin, and Ivan A. Sellin, "Radiationless Resonant Raman Scattering Interpretation of Argon Photoion Yields Measured in Coincidence with K-LL Auger Decay," Phys. Rev. A 53, 772(1996).
  4. M. A. MacDonald, S. H. Southworth, J. C. Levin, A. Henins, R. D. Deslattes, T. LeBrun, Y. Azuma, P. L. Cowan, and B. A. Karlin, "Evolution of X-Ray Resonance Raman Scattering into X-Ray Fluorescence from the Excitation of Xenon Near the L3 Edge," Phys. Rev. A. 51, 3598(1995).
  5. J. C. Levin, R. T. Short, C. Biedermann, H. Cederquist, S. B. Elston, C.-S. O, and I. A. Sellin, "Determination of Mean Energies and Impact Parameters Characteristic of Charge-Changing Reactions," Phys. Rev. A. 49, 228, (1994).