Infrared absorption profiles for small acetonitrile clusters. Theory and experiment

Abstract

Infrared absorption profiles have been measured for small acetonitrile clusters by monitoring the depletion of signal intensity in a mass spectrometer as a function of CO₂ laser wavelength. The profiles have been compared with infrared spectra calculated for (CH₃CN)₄ using computer simulation methods. Classical mechanics has been used to treat the translational and rotational degrees of freedom, and perturbation theory has provided a measure of the frequencey shift induced in individual molecules by the surrounding environment. It is proposed that small acetronitrile clusters are solid-like with an internal temperature of <120 K.