A STUDY OF THE SO MOLECULE WITH PHOTOELECTRON-SPECTROSCOPY USING SYNCHROTRON-RADIATION

The SO molecule has been studied by photoelectron spectroscopy using v acuum ultraviolet radiation from a synchrotron as the photon source. B oth constant ionic state (CIS) and photoelectron spectra have been rec orded. Resonances which appear in the CIS spectra recorded for selecte d vibrational levels of SO+ X (2) Pi in the photon energy region hv = 11.5-15.0 eV have been assigned to excitations to Rydberg states which converge to the SO+ a (4) Pi and A (2) Pi states and autoionize to SO + X (2) Pi. Also, resonances which appear in the CIS spectra recorded in the photon energy region 15.0-16.4 eV for selected vibrational leve ls of SO+ b (4) Sigma(-) have been assigned to excitations to Rydberg states which converge to SO+ B (2) Sigma(-) and autoionize to SO+ b (4 ) Sigma(-). Photoelectron spectra recorded at selected resonant photon wavelengths show that autoionization can dramatically alter the inten sities of the vibrational components in a photoelectron band and may a llow extra vibrational structure to be observed. The additional inform ation obtained from using this method to study short-lived molecules i s discussed. (C) 1997 American Institute of Physics.