Photoionization-efficiency studies of some simple inorganic molecules

High resolution (0.14 A FWHM) photoionization efficiency (PIE) measurements of HgCl2+, HgBr2+, and HgI2+ have been obtained by the supersonic molecular beam method. This study has yielded more precise values of the ionization energies (IEs) of the 2Pi/sub 3/2g/, 2Pi/sub 1/2g/, and 2D/sub +-5/2/ states of HgX2+ (X = Cl, Br, and I) to within +- 3 MeV. Lower resolution (1.4 A FWHM) studies of the HgX2 fragment ions have been undertaken and values of the binding energies of HgX+ and HgX have been calculated from the measured appearance energies (AEs) of HgX+ and X+. In addition, PIE studies of the CO2, N2O, CO, N2, NO, and O2 dimers and clusters have been performed, yielding the IEs of (CO2)/sub n=2-4/, (N2O)2, (CO)/sub n=2,3/, (N2)/sub n=2,3/, and (NO)/sub n=2-6/, and the AEs of N2O3+ from (N2O)2, O3+ from (O2)2, O5+ from (O2)3, and O7+ from (O2)4. Analysis of the PIE curves of (CO2)2+ and (N2O)2+ indicates that electronic predissociation may be an important dissociation mechanism for the CO2*/sub (n)/.CO2 and N2O*/sub (n)/.N2O Rydberg dimers. From the IEs of (NO)/sub n/, n=1-6, solvation energies of NO+ by one to five NO molecules have been determined. By analysis of the PIE spectra for O3+, O5+, and O7+, and by comparing their relative intensities, insights concerning the internal energy effects on ion-molecule half reactions have been obtained