Tunneling splittings in vibronic energy levels of [formula omitted] studied by high resolution photoelectron spectroscopy and ab initio calculation

Abstract

The energy levels of CD3F+(X∼2E) have been measured up to 1400cm−1 above the ground vibrational state using the one-photon zero-kinetic energy photoelectron (ZEKE) spectroscopic method. The spin-vibronic energy levels have also been calculated using an ab initio diabatic model. The potential energy surfaces of CD3F+ were calculated from those of CH3F+ using a transformation of the normal coordinates. The calculations show that tunneling splittings of vibrational energy levels exist due to the three equivalent wells caused by the linear-plus-strong quadratic Jahn–Teller coupling. The splittings are smaller than those in CH3F+. The experimental spectrum was assigned based on the fundamental vibrational modes calculated at the energy minimum. The calculated spin-vibronic energy levels are in good agreement with the experimental data. The tunneling splitting pairs for the fundamental vibrations related to the CD3 rock were observed. The first adiabatic ionization energy was determined as 101534±3cm−1 or 12.5886±0.0004eV.