Anharmonicity-driven redshift and broadening of sharp terahertz features of α-glycine single crystal from 20 K to 300 K: Theory and experiment
journal contribution
posted on 2024-11-17, 16:45authored byJ L Allen, T J Sanders, J Horvat, R A Lewis
For the first time, large single crystals of the simplest amino acid, glycine, have been used to determine the temperature dependence of its terahertz spectrum. High-quality spectra with very sharp absorption features are observed at cryogenic temperatures. The α-glycine structure and the purity of the crystals were verified via Raman spectroscopy and X-ray diffraction. Spectral redshift with increasing temperature was observed for all absorption bands in the terahertz region (10–250 cm , or 1–8 THz) over the temperature range of 20–300 K. X-ray diffraction revealed expansion in all planes of the crystal lattice over the same temperature range. A Bose-Einstein distribution was used to model the frequency position shift of the two lowest-energy fundamental modes at 50 cm and 69 cm . On this basis, we attribute the observed redshift and broadening with increasing temperature to the anharmonic potential associated with the phonon bath. −1 −1 −1
Funding
Australian Research Council (LE170100020)
History
Journal title
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy