Date of Award

4-2001

Degree Name

Doctor of Philosophy

Department

Physics

First Advisor

Dr. Thomas W. Gorczyca

Second Advisor

Dr. John Tanis

Third Advisor

Dr. Emanuel Kamber

Fourth Advisor

Dr. John Miller

Abstract

The use of a third generation Synchrotron Radiation source combined with timeof- flight (TOF) electron spectrometers and a two-dimensional (2D) imaging technique makes it possible to investigate and reveal new aspects of atomic and molecular structure, and allows a better understanding of electron correlation. This dissertation concentrates on the experimental study of the interaction of synchrotron radiation with argon atoms and chlorine molecules in the gas phase. The measurements were performed using a twodimensional photoelectron spectroscopy technique in combination with the high resolution Atomic, Molecular and Optical Physics undulator beam line at the Advanced Light Source at the Lawrence Berkeley National Laboratory. The complete angleresolved 2D experimental images of the electron emission following photoexcitation and photoionization of the 2p inner-shell in Ar and Cl2 were measured. For argon, the intensity profiles as a function of photon energy for all accessible Auger decay channels were studied for the first time. Significant asymmetries are observed in these various partial cross-sections, due to the interference between direct photoionization and resonant photoexcitation leading to the same final ionic state. For chlorine, Auger electron spectra following the decay of the 2p→σ* and 2p→nl resonances were analyzed. It was found that valence photoionization channels do not resonate strongly for photon energies equal to the core-to-Rydberg excitation, in contrast to the strongly resonating ones observed in the HCl molecule. Auger decay spectra of the 2p-1σ* resonances showed no evidence of atomic transitions in Cl2, indicative of no significant dissociation, also in contrast to HCl. In addition, angular distributions of the photo- and Auger electron lines were derived. These results contribute to a better understanding of atomic and molecular structure and dynamics of inner shell processes and hopefully will stimulate further experimental and theoretical work.

Access Setting

Dissertation-Abstract Only

Restricted to Campus until

4-2038

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