"In the first experiment, the stabilization process of doubly excited states in Barium was examined for the case when a laser field was used to induce stimulated emission of the excited core electron. Stabilization is referred to all the atoms that form a singly excited neutral state after being in a doubly excited autoionizing state. Relative to pure fluorescence, the application of a laser pulse which was long relative to the autoionization lifetime was found to increase the number of atoms that were stabilized. Shake-up spectra in which the principal quantum number of both electrons changes during the stimulated emission process was also clearly demonstrated. In the second experiment, a short laser pulse (short relative to the autoionization lifetime) was used to stimulate doubly excited Calcium atoms to form a stable configuration. Because the stimulated emission process happens on a fast time scale, more atoms were stabilized before they had a chance to autoionize. As a result, much larger enhancement factors were achieved. In the third and final experiment, a direct measurement of the oscillations between degenerate bound state configurations in a rapidly autoionizing system was clearly demonstrated. Because of the short pulse excitation, the atom was prepared in one of many accessible two-electron configurations. This state of the atom was not an energy eigenstate but a non-stationary wavepacket. The evolution of these wavepackets was monitored by changing the timing between the exciting "pump" laser and the stimulating "probe" laser"--Abstract, page iv.
Missouri University of Science and Technology
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