Matrix-isolation study of cluster formation in methanol: O–H stretching region

Abstract

The process of hydrogen-bonded cluster formation in methyl alcohol was investigated by FTIR spectroscopy using a matrix-isolation technique. Temperature dependence of the registered spectra of methanol trapped in an Ar matrix in the frequency region of O–H stretch fundamental was analyzed. The transformation of the FTIR bands of free O–H groups (3600–3800 cm − 1 ) into diffuse bands (3000–3600 cm − 1 ), which were assigned to the vibrations of the H-bonded hydroxyl groups in various clusters, was monitored in its initial stage at matrix heating from 10 K to 50 K. For the interpretation of the obtained experimental data the results of quantum-chemical simulation were used. The ab initio calculation was carried out at the DFT level of theory using the Gaussian 03 program with B3LYP potential and 6-31G(d) basis functions set. The similarity of the registered spectra of methanol trapped in the Ar matrix at 10–20 K to the gas-phase spectra of methanol and their gradual transformation with matrix heating to the ones similar to the spectra of liquid methanol (at 40–50 K) allows making the conclusion that such experiments may be considered as the proof of structural transformations in methyl alcohol during the phase transition from gas to liquid.