High frequency wavelength modulation cw slit jet diode laser spectrometer for characterizing ground state intermolecular hydrogen bonded vibrations

Abstract

A high frequency wavelength modulation near infrared diode laser spectrometer with a cw supersonic slit jet is described that is capable of providing rovibrational data for ground state intermolecular fundamentals in hydrogen bonded complexes. The spectrometer performance is initially characterized by investigation of rovibrational transitions in the ν2+ bands of the common isotopomers of the hydrogen bonded dimer (HBr)2. Analyses of the ν2+ and ν+2−ν51 vibrations in the homomolecular dimer (HI)2 are then used to provide molecular parameters for determination of the intermolecular ν51 band of this complex at 14.3216(20) cm−1. As a further illustration of the spectrometer performance, rovibrational analysis of the ν2, ν2+ν51 and ν2+ν51−ν51 bands in the heteromolecular complex OC:HI are used to generate molecular parameters for intermolecular fundamentals associated with both a hydrogen bonded form and a van der Waals isomeric form in this dimer. The band origin frequencies of the ν51 OC–HI and ν51 OC–IH vibrations are determined to be at 25.8917(20) and 28.3100(20) cm−1, respectively.