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

Employing molecular beam depletion spectroscopy and Fourier transform infrared matrix spectroscopy, respectively, we have studied the O–H stretching vibrations of the glycine conformers I, II, and III. The glycine molecules were either deposited into large liquid helium clusters HeN, N̄=11000, THe=0.4 K) or trapped in various rare gas matrices (Ne, Ar, Kr) at temperatures below 12 K. By extrapolating the experimental data plotted as a function of the square root of the critical temperature of the matrix material, 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 recent ab initio calculations.