Spectroscopic Studies of Energy Transfer in Low Temperature Matrices

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In this project in the Physical Chemistry Program of the Chemistry Division, Gilbert will investigate the spectroscopy and photochemistry of various nitrogen- and phosphorus-containing small inorganic radicals and molecules, such as energetic halogen amines and phosphenes, in low-temperature matrices. Energy transfer will be studied in species such as NX2 and PX2, where X = F, Cl. The intermediates produced in the photolysis of M(N3)3, where M is a Group 3 atom, will also be examined. Ultraviolet/visible absorption and laser-induced fluorescence spectra will be obtained from the matrix-isolated species to characterize their electronic states as well as to aid in understanding the photodissociation dynamics of the gas-phase compounds and their intermediates. Gaussian 94 calculations will be carried out on the radicals formed. The family of nitrogen-containing compounds known as halogen amines as well as that of azide compounds are interesting because they are notoriously unstable under standard conditions of temperature and pressure. The reasons for this behavior are not understood, but certain trends are observed, such as increasing instability in going from compounds containing fluorine to those containing chlorine, bromine, and finally iodine. An understanding of these issues in the halogen amines and comparison with the phosphorus compounds may aid in elucidating the chemical nature of other nitrogen- and phosphorus-bearing species. Practical applications include the chemical etching of surfaces in semiconductor processing, tribological thin-film coatings, and better reagents for electronic-transition chemical laser systems.