The origin of 1560 cm−1 band in experimental IR spectra of water adsorbed on TiO2 surface: Ab initio assessment

Abstract We present DFT study on vibrational spectrum of water layer on a surface of TiO 2 which is modeled via Ti 8 O 16 nanocluster. In contrast to ν 2 mode’s frequency of liquid water (1645 cm −1 ) for the water layer theory predicts considerably lower ν 2 frequency (1570 cm −1 ) which matches experimentally observed shoulder in IR spectrum (1560 cm −1 ). We demonstrate that the calculated ν 2 frequencies depend linearly on a distance between adsorbed water molecules and a surface of Ti 8 O 16 nanocluster! We also show that hydrogen bonding strongly affects ν 1 vibrational frequencies but leaves ν 2 and ν 3 ones almost intact.