Infrared spectra and structure of water clusters trapped in argon and krypton matrices

The infrared spectra of water clusters trapped in argon and krypton matrices have been analyzed on the basis of recent quantum chemical calculations. Comparing the observed spectra with the band positions and intensities estimated by calculations for the water clusters, we have identified almost all bands observed in the bonded OH stretching region. In addition to the absorptions of the cyclic water trimer, tetramer, and pentamer, the present analysis reveals some infrared bands of the cage and book isomers of the water hexamer. For the cyclic pentamer, the second bonded OH stretching band is found to be absent or very weak, in contrast to the quantum chemical calculations.