Influence of an argon matrix on trapped ethanol clusters

Spectral band positions in FTIR spectra of ethanol in gaseous state and in matrix isolation differ by several wavenumbers. In order to explain the observed matrix shift, quantum chemical calculations (DFT, B3LYP/cc-pVTZ level of theory) of optimal structure and vibrational frequencies of ethanol monomer, dimer and trimer in vacuum, as well as in ethanol and argon environments, were carried out. The calculated frequencies of IR absorption bands for three different environments show that the effect of the environment is manifested as a red shift of the spectral bands corresponding to the most part of the vibrational modes, and a blue shift of the bands of the stretching C–H vibrations. Dimer structure was found to be the most affected by both ethanol and argon environments. It is shown that the ethanol environment has a stronger effect on the structure and vibrational spectra of ethanol clusters than the argon environment.