The O-H stretching vibrations of glycine trapped in rare gas matrices and helium clusters

Employing molecular beam depletion spectroscopy and Fourier transform infra red matrix spectroscopy, respectively, we have studied the O-H stretching v ibrations of the glycine conformers I, II, and III. The glycine molecules w ere either deposited into large liquid helium clusters He-N, (N) over bar=1 1000, T-He=0.4 K) or trapped in various rare gas matrices (Ne, Ar, Kr) at t emperatures below 12 K. By extrapolating the experimental data plotted as a function of the square root of the critical temperature of the matrix mate rial, the positions of the gas phase absorption bands were estimated to be 3585 +/- 2 cm(-1) (conformer I), 3295 +/- 3 cm(-1) (conformer II), and 3580 +/- 5 cm(-1) (conformer III). The experimental results are compared with r ecent ab initio calculations. (C) 1999 American Institute of Physics. [S002 1-9606(99)00931-9].