POTENTIAL-ENERGY SURFACE AND VIBRATIONAL ANALYSIS ALONG THE STRETCHING VIBRATIONS OF XEHXE+ ION

An analytical potential energy surface (PES) along the stretching coor dinates of a linear XeHXe+ ion is presented. Ab initio calculations wi thin the effective core potential approach are used as input for the P ES. The present vibrational analysis indicates extensive mixing of the zeroth-order harmonic oscillator vibrational states, and a rather com plete collapse of the normal mode picture already near the bottom of t he potential well. At higher vibrational energies, and elongated Xe-Xe distances, development of a double minimum in the PES is observed. Th e simulated absorption spectrum consists of a strong vibrational progr ession near 1000-1700 cm-1, and is in qualitative agreement with the p revious matrix isolation data. The intensity distribution of the vibra tional progression is mostly due to the potential terms rather than no nlinear contributions in the Taylor series expansion of the electric d ipole moment. Due to the highly anharmonic potential, and subsequent b reakdown of selection rules, the emission spectrum is predicted to be particularly rich in the 850-1500 cm-1 spectral region. Several of the vibrational transitions possess transition dipoles exceeding 1 D.