Raman and Terahertz Spectroscopy of Low-Frequency Chiral Phonons in Amino Acids

doi:10.1021/acs.nanolett.6c00060

Raman and Terahertz Spectroscopy of Low-Frequency Chiral Phonons in Amino Acids

2026-04-01

0

PRE

AI

DOI：10.1021/acs.nanolett.6c00060

Original

Original request for help

Save

Abstract

En 中文

Chiral phonons are mirror-symmetric vibrations with nonzero angular momenta that correspond to twisting and rotational motions of multiple atoms. In chiral crystals, these include low-energy terahertz (THz)-range vibrations of the molecular segments involving dozens of atoms with energies sensitive to molecular chirality. Here, we present spectral signatures of chiral phonons in circularly polarized Raman optical activity (ROA) spectra from enantiomers of amino acid crystals. Along with complementary THz circular dichroism (TCD) measurements, our ROA data reveal several vibrational bands in enantiomers of valine, alanine, tyrosine, and proline between 30 and 150 cm-1 (similar to 1-4.5 THz) that exhibit opposite intensities. Density functional theory calculations confirm their assignment to twisting and shearing molecular motions. The simultaneous registration of chiral phonon modes by ROA and TCD demonstrates the necessity of these complementary techniques to identify complex mirror-asymmetric vibrational modes and offers new insights into their interactions with circularly polarized light.

Keywords:

chiral phonons

Raman optical activity

terahertzspectroscopy

terahertz circular dichroism (TCD)

amino acids

collective motions

Raman and Terahertz Spectroscopy of Low-Frequency Chiral Phonons in Amino Acids

Abstract

Journal

Organization