Dr. Spudis earned his master's degree from Brown University and his Ph.D. from Arizona State University in Geology with a focus on the Moon. His career included work at the US Geological Survey,

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Photoionization of the OH and OD radicals, produced from the H+NO2 and D+NO2 reactions, has been studied in the gas phase in the photon energy region 13.0–17.0 eV using constant ionic state (CIS) and photoelectron spectroscopy (PES) employing synchrotron radiation. Structure in the CIS spectra, recorded for the first and second photoelectron bands, has been assigned to excitation to (a 1Δ,3d) and (A 3Π,3d) Rydberg states. A comparison of vibrationally specific OH and OD CIS spectra, and photoelectron spectra recorded at resonant wavelengths, has allowed a more complete assignment of structure observed in earlier photoionization mass spectrometric measurements. These assignments have been supported by the results of Franck–Condon calculations. The CIS spectra have been shown to be dominated by structure arising from excitation from the outermost valence molecular orbitals of OH [the nonbonding 1π(O 2p) orbital and the bonding 3σ orbital] to O nd Rydberg orbitals. Photoelectron spectra recorded for the first bands of OH and OD at resonant photon energies have allowed more extensive vibrational structure to be obtained than has previously been recorded by PES experiments performed with inert gas discharge photon sources.

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Dissociation and ionization processes in dimethyl disulfide, CH(3)S(2)CH(3), induced by one- or two-photon absorption of 193 nm light, have been studied using velocity-map ion imaging. The analysis of the ion images of the CH(3)S(2) (+), CH(3)S(+), S(2) (+), and S(+) fragments has allowed the characterization of the scattering dynamics of some of the main photolysis and dissociative-ionization processes. In particular, the experiments corroborate the formation of electronically excited SCH(3)((2)A(1)) products in the 193 nm photodissociation of dimethyl disulfide seen in earlier studies, and show that laser ionization provides a very sensitive method for their detection. The data have also allowed determination of the recoil energy and angular distributions of the CH(3)S(2) (+) and CH(3)S(+) products of the two-photon dissociative-ionization of the CH(3)S(2)CH(3) molecule. The measured distributions for these products are consistent with the formation of a transient parent ion which dissociates after a substantial intramolecular rearrangement, possibly yielding the most stable isomeric forms of the fragments, namely CH(2)S(2)H(+) and CH(2)SH(+).