The asymmetric cage structure of (H2O)(7) from a combined spectroscopic and computational study

The vibrational OH stretch spectra have been measured for the size-selected pure water clusters (H2O)(7). In contrast to (H2O)(n), n = 8-10 clusters, which exhibit three distinct bands corresponding to three distinct types of OH bonds, the heptamer spectrum displays seven bands spanning the range fr om 2935 to 3720 cm(-1). Calculations suggest that the spectra originate fro m two isomers, derived from the S-4 octamer cube by removal of either one d ouble donor or one double acceptor water molecule. (C) 1999 American Instit ute of Physics. [S0021-9606(99)01622-0].