Dynamics of Core Electron Excitation and Decay in Molecules. Monochromatic synchrotron radiation is used to excite molecules in molecular beams in the region of the K edge of carbon, nitrogen, oxygen, and fluorine and the L edge of silicon, sulfur, phosphorous, and chlorine. The excitation is selective since the tightly bound core electrons of specific atoms can be excited to distinct final state configurations. Core-hole excited state symmetries and the photoabsorption anisotropy are determined from the angular distribution of dissociation fragments. Electron-energy spectroscopy measures branching ratios to different Auger, resonance Auger, and autoionization pathways. Time-of-flight mass spectroscopy identifies dissociation products, and electron-multiple ion coincidence techniques allow the dissociation channels to be related to the electronic decay channels. Coincidence maps provide information about the kinematics of the dissociation, including angle, momentum, and kinetic energy distributions. Visible and ultraviolet luminescence reveals neutral fragments created in excited electronic states and serves as a high resolution probe of the Auger final state. Vibrational and rotational branching ratios thus obtained provide information about bond-length dependent properties of core-electron resonances, interference effects resulting from lifetime broadening of the vibrational levels of core-hole excited states, interchannel coupling of ionization continua, and the partitioning of angular momentum.

     Synchrotron Radiation Induced Chemistry in Films and on Surfaces. This research is directed at elucidating novel chemical processes induced by synchrotron radiation in the condensed phase. Such knowledge may prove useful in microfabrication technology, specifically in the development of high resolution or high sensitivity resists, in the development of resist-free processing, and in the utilization of mild processing conditions. The photochemistry induced by synchrotron radiation in condensed films, cryogenic matrices, and surface adsorbates is monitored by Fourier transform infrared spectroscopy, high resolution electron energy loss spectroscopy, and mass spectroscopy. Etching and deposition rates are measured by laser interferometry. The nature of the reactions, the reaction rates, and the dependence on photon energy are of interest. The initial emphasis is on soft x-ray induced processes and on determining the degree to which the chemistry is correlated with the atomic site of the core-hole and the excited-state configuration. Subsequent efforts will include the vuv region and studies leading to an understanding of the electron and energy transfer processes that produce photochemistry in a region around the excitation site.

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