Low-frequency Raman optical activity provides insight into the structure of chiral liquids

0560563 - ÚOCHB 2023 RIV GB eng J - Journal Article
Michal, P. - Kapitán, J. - Kessler, J. - Bouř, Petr
Low-frequency Raman optical activity provides insight into the structure of chiral liquids.
Physical Chemistry Chemical Physics. Roč. 24, č. 33 (2022), s. 19722-19733. ISSN 1463-9076. E-ISSN 1463-9084
R&D Projects: GA ČR(CZ) GA20-10144S; GA ČR(CZ) GA22-04669S; GA MŠMT(CZ) EF16_019/0000729
Research Infrastructure: e-INFRA CZ - 90140
Institutional support: RVO:61388963
Keywords : molecular property tensors * normal mode optimatization * Rayleigh scattering
OECD category: Physical chemistry
Impact factor: 3.3, year: 2022
Method of publishing: Limited access
https://doi.org/10.1039/D2CP02290G

Vibrational frequencies of modes involving intermolecular motions in liquids are relatively small, in the Raman scattering close to the excitation frequency, and the bands may merge into a diverging uninterpretable signal. Raman optical activity (ROA) spectral shapes in this region, however, are structured more and may better reflect the nature of the studied systems. To understand the origin of the signal and its relation to the molecules, ROA spectra of six chiral neat liquids are recorded and analyzed on the basis of molecular dynamics and density functional theory computations. The theory of Raman scattering of liquids is discussed and adapted for modeling based on clusters and periodic boundary conditions. A plain cluster approach is compared to a crystal-like model. The results show that the low-frequency optical activity can be reliably modeled and related to the structure. However, momentary arrangement of molecules leads to large variations of optical activity, and a relatively large number of geometries need to be averaged for accurate simulations. The intermolecular modes are intertwined with intramolecular ones and start to dominate as the frequency goes down. The low-frequency ROA signal thus reflects the chemical composition and coupled with the modeling it provides a welcome means to study the structure and interactions of chiral liquids.
Permanent Link: https://hdl.handle.net/11104/0333431