Infrared spectra of water clusters in krypton and xenon matrices

The infrared absorption spectra of the water molecules and small water clusters, (H(2)O)(n) with n = 2-6, trapped in solid argon, krypton, and xenon matrices have been investigated. The infrared bands of the water clusters with n = 5 and 6 in krypton and n = 3, 4, 5, and 6 in xenon matrices have been identified for the first time in the bonded OH stretching region. The frequency shifts in the bonded OH stretching band of the water dimer and trimer in xenon matrices show fairly large deviations to the red from the empirical correlation between the matrix shifts and the square root of the critical temperatures of the matrix material. The observed anomalous shifts suggest that the water dimer and trimer in solid xenon are trapped in multiple sites, and that the structures of the preferential trapping sites are different from those in argon and krypton matrices.