An experimental and computational study of the effect of aqueous solution on the multiphoton ionisation photoelectron spectrum of phenol. (20th September 2019) - Henley, Alice
Abstract : We revisit the photoelectron spectroscopy of aqueous phenol in an effort to improve our understanding of the impact of inhomogeneous broadening and inelastic scattering on solution-phase photoelectron spectra. Abstract : We revisit the photoelectron spectroscopy of aqueous phenol in an effort to improve our understanding of the impact of inhomogeneous broadening and inelastic scattering on solution-phase photoelectron spectra. Following resonance-enhanced multiphoton ionisation via the 1 1 ππ* and 1 1 πσ* states of phenol, we observe 1 1 ππ*–D0 /D1 ionisation and competing direct S0 –D0 /D1 ionisation. Following resonance-enhanced multiphoton ionisation via the 2 1 ππ* state, we observe the signature of solvated electrons. By comparing the photoelectron spectra of aqueous phenol with those of gas-phase phenol, we find that inelastic scattering results in peak shifts with similar values to those that have been observed in photoelectron spectra of solvated electrons, highlighting the need for a robust way of deconvoluting the effect of inelastic scattering from liquid-phase photoelectron spectra. We also present a computational strategy for calculating vertical ionisation energies using a quantum-mechanics/effective fragmentation potential (QM/EFP) approach, in which we find that optimising the configurations obtained from molecular dynamics simulations and using the [phenol·(H2 O)5 ]QM [(H2 O) n ≥250 ]EFP (B3LYP/aug-cc-pvdz) method gives good agreement with experiment.