Dr. Jon LevinProfessor
Ph.D., University of Oregon, 1986
Office: M-103 Nielsen
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 VitaProfessor 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