High resolution zero kinetic energy photoelectron spectroscopy of benzene and determination of the ionization potential

Abstract

We report the direct high-resolution determination of the ionization potential of benzene and the observation of rotational structure in the vibronic ground state of the benzene ion. We employ a new technique of two-color high-resolution zero kinetic energy photoelectron spectroscopy (ZEKE-PES) via selection of an intermediate resonant (neutral) state. The ZEKE-PES method allows for the investigation of rotationally resolved photoionization dynamics and the direct high-precision determination of ionization potentials, the precision being derived directly from the laser wavelength calibration. For benzene we determine an IP of 74 555.0±0.4 cm−1. We compare this method to ionization potential measurements from ion yield measurements under various conditions.