Characterizations of the hydrogen-bond structures of 2-naphthol-(H2O)n (n=0–3 and 5) clusters by infrared-ultraviolet double-resonance spectroscopy

Abstract

OH stretching vibrations of 2-naphthol-(H2O)n (n=0–3 and 5) hydrogen-bonded clusters in the S0 state have been observed by infrared-ultraviolet (IR-UV) double-resonance spectroscopy. In bare 2-naphthol, cis- and trans-isomers were identified by the comparison of the observed OH frequencies with those obtained by ab initio calculations with the HF/6-31G basis set. The OH stretching vibrations (νOH) of hydrogen-bonded 2-naphthol-(H2O)n show characteristic shifts depending on the cluster size. They are classified into hydrogen-bonded νOH, and νOH free from the hydrogen bond. The cluster structures were also examined by comparing the observed IR spectra with simulated ones. It was found that the clusters with n=2 and 3 form ring structures, while the cluster with n=5 exhibits an ice (I) structure.