Vibrational spectroscopy for size-selected fluorene-(H2O)n=1,2 clusters insupersonic jets

The OH and CH stretching vibrations of fluorene-(H2O)(n=1,2) clusters have been observed by IR-UV and stimulated Raman-UV double resonance spectroscop y in supersonic jets. For fluorene-(H2O)(1), a clear intensity alternation was observed for the symmetric and antisymmetric OH stretching modes in the IR and the Raman spectra, while in fluorene-(H2O)(2) the IR spectrum of th e OH stretching vibration indicates the water dimer formation in the cluste r. For the CH stretching vibration it was found that the aliphatic CH stret ching vibration shows a remarkable blue shift in the clusters. From the obs erved spectra and the ab initio calculations at HF/6-31G and HF/G-31G(d,p) levels, it was concluded that the n = 1 and 2 clusters have similar structu res in which the water monomer or the dimer locates above the plane of fluo rene.