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

Fuente: arXiv
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Main Authors: Rao, Rahul, Choi, Won Jin, Slocik, Joseph M., Mai, Thuc T., Susner, Michael A., Collins, Kelsey A., Newburger, Michael J., Bouř, Petr, Kotov, Nicholas A.
Format: Preprint
Published: 2026
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author Rao, Rahul
Choi, Won Jin
Slocik, Joseph M.
Mai, Thuc T.
Susner, Michael A.
Collins, Kelsey A.
Newburger, Michael J.
Bouř, Petr
Kotov, Nicholas A.
author_facet Rao, Rahul
Choi, Won Jin
Slocik, Joseph M.
Mai, Thuc T.
Susner, Michael A.
Collins, Kelsey A.
Newburger, Michael J.
Bouř, Petr
Kotov, Nicholas A.
contents Chiral phonons are mirror-symmetric vibrations that correspond to twisting and rotational motions of atoms. In chiral biomolecules, they correspond to low-energy terahertz (THz)-range vibrations of the molecular segments involving dozens of atoms whose energies are sensitive to the chirality of the molecules and local atomic geometries. Here we present spectral signatures of chiral phonons in circularly polarized low-frequency Raman and Raman optical activity (ROA) spectra from crystals of several amino acids in different enantiomeric forms. Along with complementary THz circular dichroism (TCD) measurements, our ROA data reveal two sets of bisignate peaks in valine, alanine, tyrosine and proline between 1 and 4.5 THz that are more intense than the ROA peaks in the fingerprint region. Density functional theory (DFT) calculations on L-alanine attribute these modes to twisting and shearing molecular motions. The strong agreement between the ROA and TCD data demonstrates the power of these complementary vibrational spectroscopy techniques to identify chiral phonons in biomolecules, and offers new insights into their vibrational properties and interactions with circularly polarized light.
format Preprint
id arxiv_https___arxiv_org_abs_2603_27920
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Raman and Terahertz Spectroscopy of Low-Frequency Chiral Phonons in Amino Acids
Rao, Rahul
Choi, Won Jin
Slocik, Joseph M.
Mai, Thuc T.
Susner, Michael A.
Collins, Kelsey A.
Newburger, Michael J.
Bouř, Petr
Kotov, Nicholas A.
Materials Science
Chiral phonons are mirror-symmetric vibrations that correspond to twisting and rotational motions of atoms. In chiral biomolecules, they correspond to low-energy terahertz (THz)-range vibrations of the molecular segments involving dozens of atoms whose energies are sensitive to the chirality of the molecules and local atomic geometries. Here we present spectral signatures of chiral phonons in circularly polarized low-frequency Raman and Raman optical activity (ROA) spectra from crystals of several amino acids in different enantiomeric forms. Along with complementary THz circular dichroism (TCD) measurements, our ROA data reveal two sets of bisignate peaks in valine, alanine, tyrosine and proline between 1 and 4.5 THz that are more intense than the ROA peaks in the fingerprint region. Density functional theory (DFT) calculations on L-alanine attribute these modes to twisting and shearing molecular motions. The strong agreement between the ROA and TCD data demonstrates the power of these complementary vibrational spectroscopy techniques to identify chiral phonons in biomolecules, and offers new insights into their vibrational properties and interactions with circularly polarized light.
title Raman and Terahertz Spectroscopy of Low-Frequency Chiral Phonons in Amino Acids
topic Materials Science
url https://arxiv.org/abs/2603.27920