SINGLE-PHOTON IONIZATION STUDY OF THE VIBRATIONAL STRUCTURE IN THE GROUND-STATE OF XE2+

The vibrationally resolved spectra of the ground state A 2SIGMA(u)+ of Xe2+ were observed at wavelengths from 1023 angstrom to 1116 angstrom by using the method of single-photon ionization with synchrotron radiation as a light source. A long progression beginning at v = 0 was clearly observed in the threshold electron spectra for the first time. The spectroscopic parameters for the ground state of Xe2+ (average mass = 131.3. 131.3) calculated from the experimental data are: omega(e) = 122.9 (+/-0.1) cm-1, omega(e)chi(e) = 0.481 (+/-0.001) cm-1, the dissociation energy D0 = 7849 (+/-9) cm-1, the zero point energy 61.3 (+/-0.1) cm-1, T(e) = 90 119 (+/-8) cm-1, and the adiabatic ionization potential 90 170 (+/-8) cm-1. New autoionizing Rydberg series were found and assigned to converge to the C 2PI3/2u and B 2PI1/2g states of Xe2+.