Infrared study of glycolaldehyde isolated in parahydrogen matrix.

The infrared spectrum of glycolaldehyde sugar model in solid parahydrogen is reported and interpreted in the light of ab initio anharmonic frequency calculations. The advantages of parahydrogen lead to a simplification of its infrared spectroscopy compared to other conventional matrices. Surprisingly, the sugar molecule is found to display an unexpected large bandwidth compared to the smaller organic molecules studied in parahydrogen so far. Among them, only glycolaldehyde possesses an internal hydrogen-bond. Band broadening in glycolaldehyde is interpreted as originating mainly from the presence of the hydrogen-bond and to a lesser extent from clustering with oH(2) impurities.