Infrared spectroscopy of O˙- and OH- in water clusters: evidence for fast interconversion between O˙- and OH˙OH

Phys Chem Chem Phys. 2017 Sep 27;19(37):25346-25351. doi: 10.1039/c7cp04577h.

Abstract

We present infrared multiple photon dissociation (IRMPD) spectra of (H2O)n- and (H2O)nOH- cluster ensembles for n[combining macron] ≈ 8 and 47 in the range of 2400-4000 cm-1. Both hydrated ions exhibit the same spectral features, in good agreement with theoretical calculations. Decomposition of the calculated spectra shows that bands originating from H2OO˙- and H2OOH- interactions span almost the whole spectral region of interest. Experimentally, evaporation of OH˙ is observed to a small extent, which requires interconversion of (H2O)n- into (H2O)n-1OH˙OH-, with subsequent H2O evaporation preferred over OH˙ evaporation. The modeling shows that (H2O)n- and (H2O)n-1OH˙OH- cannot be distinguished by IRMPD spectroscopy.