High-resolution Photoelectron Spectroscopy of Cryogenically Cooled TiO₂CH₃OH⁻: An Investigation of Methanol Splitting by TiO₂^−/0†

High-resolution photoelectron spectra of cryogenically cooled TiO₂CH₃OH⁻ anions obtained with slow electron velocity-map imaging are reported and used to explore the reactions of TiO₂^−/0 with methanol. The highly structured spectra were compared with results from DFT calculations to determine the dominant structure to be cis-CH₃OTi(O)OH⁻, a dissociative adduct in which CH₃OH is split by TiO₂⁻. The experiment yields an electron affinity of 1.2152(7) eV for TiO₂CH₃OH as well as several vibrational frequencies for the neutral species. Comparison to Franck−Condon (FC) simulations shows that while most experimental features appear in the simulations, several are not and are assigned to FC-forbidden transitions involving non-totally symmetric vibrational modes. The FC-allowed and forbidden transitions also exhibit different photoelectron angular distributions. The FC-forbidden transitions are attributed to Herzberg−Teller (HT) coupling with the \tilde A^2A'' excited state of the anion. The results are compared to previous cryogenic slow electron velocity-map imaging (cryo-SEVI) studies of bare TiO₂⁻ and the water-split adduct TiO₃H₂⁻.