The 3, 5, 6, and 7 THz resonances of α-glycine

Using an optically thin single crystal sample, mounted in a cryostat permitting cooling to 6 K, and a synchrotron as a bright light source, exceptionally well defined absorption spectra of well-characterised alpha-glycine have been obtained in the spectral range 2.5-7.5 THz (approximately 80-240 cm(-1)). Four separate resonances have been observed, respectively at 93, 152, 188, and 223 cm(-1) at the lowest temperature. Each reduces in frequency (redshifts) as temperature increases. The origin of this observed behaviour is attributed to a phonon-mediated anharmonicity in the crystal potential. Crown Copyright (C) 2021 Published by Elsevier B.V. All rights reserved.

Automated summary

Well-defined absorption spectra of well-characterised alpha-glycine were obtained in the spectral range 2.5-7.5 THz, with four separate resonances observed at 93, 152, 188, and 223 cm(-1) at the lowest temperature. The observed frequency reduction with increasing temperature is attributed to phonon-mediated anharmonicity in the crystal potential.