Raman study of water deposited in solid argon matrix

Vlasta Mohaček-Grošev; Krešimir Furić; Vedran Vujnović

doi:10.1016/j.saa.2021.120770

Raman study of water deposited in solid argon matrix

Spectrochim Acta A Mol Biomol Spectrosc. 2022 Mar 15:269:120770. doi: 10.1016/j.saa.2021.120770. Epub 2021 Dec 16.

Authors

Vlasta Mohaček-Grošev¹, Krešimir Furić², Vedran Vujnović³

Affiliations

¹ Center of Excellence for Advanced Materials and Sensing Devices, Research Unit New Functional Materials, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia. Electronic address: Vlasta.Mohacek.Grosev@irb.hr.
² Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia.
³ Department of Physics and Centre for Micro- and Nanosciences and Technologies, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia. Electronic address: vedran.vujnovic@phy.uniri.hr.

PMID: 34954478
DOI: 10.1016/j.saa.2021.120770

Abstract

New Raman data are presented concerning H₂O and D₂O water aggregation in argon matrix having the ratio of number of argon atoms to water molecules close to 40:1. Experiments were conducted at temperatures from 8 K to 34 K allowing observation of OH and OD stretching vibrations of water monomers, dimers, trimers and higher multimers, as well as broad bands corresponding to solid amorphous water. Molecular dynamics simulations were performed for thirteen or sometimes fourteen water molecules dispersed among 500 argon atoms. Resulting final configurations included dimers, trimers, tetramers and pentamers, all in open chain configurations which upon optimization resulted in mostly cyclic conformations. Observed OH stretching vibrations were assigned by comparing calculated normal modes in harmonic approximation at the B3LYP/aug-cc-pVDZ and PBEPBE1/aug-cc-pVDZ level of theory with our data and previously observed bands from infrared matrix isolation studies and Raman jet cooled experiments. Raman bands assigned to water multimers in argon matrix are shifted 20 to 25 cm^-1 towards lower wavenumbers with respect to the positions of OH stretching vibrations of almost free water clusters.

Keywords: Hydrogen bonding; Low temperature spectroscopy; Matrix isolation; Molecular dynamics simulation; Raman; Vibrations; Water clusters; Water oligomers.