Photofragmentation and electron detachment of aromatic phosphonate, sulfonate and phosphate oxyanions

Abstract

The photodetachment energy threshold, as well as vibrationally resolved spectral signatures of the lower lying excited states and dipole bound states in model aromatic phosphonate, sulfonate and phosphate oxyanions, has been investigated using a photofragmentation spectrometer equipped with a cold ion trap. The effect of the laser excitation was monitored by mass-selective detection of product ion fragments or, alternatively, measuring the yield of the complementary neutral radicals discriminated according to their kinetic energy. The anions phenylphosphate, phenylsulfonate and p-toluenesulfonate evidenced the expected behavior, characterized by the predominance of ionic fragmentation processes, at low energies, rapidly evolving to a scenario controlled by the electron photodetachment channel at higher energies. Surprisingly for such a similar system, the phenylphosphonate anion does not have any ionic fragmentation channels and only exhibits the presence of dipole bound states.