High-resolution photoelectron spectroscopy of TiO3H2-: Probing the TiO2- + H2O dissociative adduct

Jessalyn A DeVine; Ali Abou Taka; Mark C Babin; Marissa L Weichman; Hrant P Hratchian; Daniel M Neumark

doi:10.1063/1.5018414

High-resolution photoelectron spectroscopy of TiO₃H₂^-: Probing the TiO₂^- + H₂O dissociative adduct

J Chem Phys. 2018 Jun 14;148(22):222810. doi: 10.1063/1.5018414.

Authors

Jessalyn A DeVine¹, Ali Abou Taka², Mark C Babin¹, Marissa L Weichman¹, Hrant P Hratchian², Daniel M Neumark¹

Affiliations

¹ Department of Chemistry, University of California, Berkeley, California 94720, USA.
² Chemistry and Chemical Biology, University of California, Merced, California 05343, USA.

PMID: 29907033
DOI: 10.1063/1.5018414

Abstract

Slow electron velocity-map imaging spectroscopy of cryogenically cooled TiO₃H₂^- anions is used to probe the simplest titania/water reaction, TiO₂^0/- + H₂O. The resultant spectra show vibrationally resolved structure assigned to detachment from the cis-dihydroxide TiO(OH)₂^- geometry based on density functional theory calculations, demonstrating that for the reaction of the anionic TiO₂^- monomer with a single water molecule, the dissociative adduct (where the water is split) is energetically preferred over a molecularly adsorbed geometry. This work represents a significant improvement in resolution over previous measurements, yielding an electron affinity of 1.2529(4) eV as well as several vibrational frequencies for neutral TiO(OH)₂. The energy resolution of the current results combined with photoelectron angular distributions reveals Herzberg-Teller coupling-induced transitions to Franck-Condon forbidden vibrational levels of the neutral ground state. A comparison to the previously measured spectrum of bare TiO₂^- indicates that reaction with water stabilizes neutral TiO₂ more than the anion, providing insight into the fundamental chemical interactions between titania and water.