VIBRATIONAL SPECTROSCOPY OF XE2+ VIA PULSED FIELD-IONIZATION

Delayed, pulsed field ionization of extremely high-n Rydberg states has been used in combination with a high-resolution vacuum ultraviolet radiation source to measure the vibrationally resolved spectra of the first three bound states of Xe2+. For the ground state of the ion (A 2-SIGMA-u+), a long progression beginning at upsilon+ = 56 was observed which included isotopically resolved energy levels. The spectroscopic parameters obtained from a fit of the data to anharmonic oscillator energy levels are reported. The resulting Xe2 ionization potential is somewhat higher than previously reported. Several vibrations of the first excited state (B 2-PI(3/2)g) were observed near 97 000 cm-1. An absolute vibrational assignment was not possible due to an unusual alternation of intensities. Nevertheless, a lower bound on the binding energy and an estimated vibrational frequency are reported. For the C 2-PI(3/2)u state, the upsilon+ = 0-2 vibrational levels were observed with an intensity distribution consistent with the weakly bound nature of this state. The derived binding energy and vibrational frequency for the C 2-PI(3/2)u state are reported.