Photoionization of 2-pyridone and 2-hydroxypyridine

Abstract

We studied the photoionization of 2-pyridone and its tautomer, 2-hydroxypyridine by means of VUV synchrotron radiation coupled to a velocity map imaging electron/ion coincidence spectrometer. The photoionization efficiency (PIE) spectrum is composed of steps. The state energies of the [2-pyridone]⁺ cation in the ground and à excited electronic states, as well as of the [2-hydroxypyridine]⁺ cation in the electronic ground state, are determined. The slow photoelectron spectra (SPES) are dominated by the 0⁰₀ transitions to the corresponding electronic states together with several weaker bands corresponding to the population of the pure or combination vibrational bands of the cations. These vibrationally-resolved spectra compare very well with state-of-the-art calculations. Close to the ionization thresholds, the photoionization of these molecules is found to be mainly dominated by a direct process whereas the indirect route (autoionization) may contribute at higher energies.