Coherency spectral analysis of interfacial water at TiO₂ surfaces

Classical molecular dynamic studies of anatase <101> and rutile <110> surfaces immersed in bulk SPC/fw water were performed to investigate the dynamic properties of the semi-mobile water layers formed thereon. Spectral analysis techniques were used to characterise and interpret the observed dynamical behaviour, including the use of frequency domain cross-correlation measures. Both surfaces exhibit distinct layering patterns, wherein molecular motion is inhibited and certain molecular vibrational modes are augmented or diminished. There is evidence that this effect is mediated by coupling of vibrational modes between the observed layers and under-coordinated surface oxygen (O_br) atoms and may play a role in the fascinating behaviour of water at TiO₂ interfaces.