Photoelectron Spectroscopy of Benzene in the Liquid Phase and Dissolved in Liquid Ammonia

We report valence band photoelectron spectroscopy measurements of gas-phase and liquid-phase benzene as well as those of benzene dissolved in liquid ammonia, complemented by electronic structure calculations. The origins of the sizable gas-to-liquid-phase shifts in electron binding energies deduced from the benzene valence band spectral features are quantitatively characterized in terms of the Born-Haber solvation model. This model also allows to rationalize the observation of almost identical shifts in liquid ammonia and benzene despite the fact that the former solvent is polar while the latter is not. For neutral solutes like benzene, it is the electronic polarization response determined by the high frequency dielectric constant of the solvent, which is practically the same in the two liquids, that primarily determines the observed gas-to-liquid shifts.

Automated summary

Valence band photoelectron spectroscopy measurements and electronic structure calculations were used to characterize the shifts in electron binding energies of benzene from gas to liquid phase, with the Born-Haber solvation model providing quantification. Despite the difference in polarity between liquid ammonia and benzene, the shifts were primarily determined by the electronic polarization response determined by the high frequency dielectric constant of the solvent.