Vibrational spectroscopy of the hydrated hydronium cluster ions H3O+sdot;(H2O)n(n=1,thinsp;2,thinsp;3)

摘要

The gas phase infrared spectra of the hydrated hydronium cluster ions H3O+sdot;(H2O)n(n=1,thinsp;2,thinsp;3) have been observed from 3550 to 3800 cmminus;1. The new spectroscopic method developed for this study is a two color laser scheme consisting of a tunable cw infrared laser with 0.5 cmminus;1resolution used to excite the Ondash;H stretching vibrations and a cw CO2laser that dissociates the vibrationally excited cluster ion through a multiphoton process. The apparatus is a tandem mass spectrometer with a radio frequency ion trap that utilizes the following scheme: the cluster ion to be studied is first mass selected; spectroscopic interrogation then occurs in the radio frequency ion trap; finally, a fragment ion is selected and detected using ion counting techniques. The vibrational spectra obtained in this manner are compared with that taken previously using a weakly bound H2lsquo;lsquo;messenger.rsquo;rsquo; A spectrum of H7thinsp;O+3taken using a neon messenger is also presented.Abinitiostructure and frequency predictions by Remington and Schaefer are compared with the experimental results.