Raman study of water deposited in solid argon matrix
Vlasta Mohaček-Grošev1, Krešimir Furić2, Vedran Vujnović3
1Center of Excellence for Advanced Materials and Sensing Devices, Research Unit New Functional Materials, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia.
Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
|December 26, 2021
Summary
Researchers studied water aggregation in an argon matrix using Raman spectroscopy. They observed shifts in stretching vibrations for water monomers, dimers, and multimers, providing insights into their structures.
Area of Science:
- Spectroscopy
- Computational Chemistry
- Materials Science
Background:
- Water's aggregation behavior is crucial for understanding its properties.
- Matrix isolation spectroscopy and molecular dynamics simulations are key techniques for studying small molecular clusters.
- Previous studies have explored water clusters, but detailed vibrational analysis in specific matrices remains an area of interest.
Purpose of the Study:
- To investigate the vibrational properties of water (H2O) and heavy water (D2O) aggregates in an argon matrix.
- To characterize the structures of water monomers, dimers, trimers, and higher multimers using Raman spectroscopy.
- To compare experimental Raman data with theoretical calculations to assign observed vibrational bands.
Main Methods:
- Matrix isolation Raman spectroscopy at temperatures ranging from 8 K to 34 K.
- Molecular dynamics simulations of water molecules (13-14) dispersed in argon (500 atoms).
- Quantum chemical calculations (B3LYP/aug-cc-pVDZ and PBEPBE1/aug-cc-pVDZ) for vibrational mode analysis.
Main Results:
- Raman spectra revealed distinct OH and OD stretching vibrations for various water multimers.
- Simulations showed initial open-chain configurations of water clusters that optimized into cyclic forms.
- Experimental Raman bands for water multimers in argon were red-shifted by 20-25 cm⁻¹ compared to free water clusters.
Conclusions:
- The study successfully assigned Raman bands to specific water aggregates in an argon matrix.
- The observed vibrational shifts provide evidence for the structural characteristics of water clusters.
- This research enhances the understanding of water molecule interactions and aggregation in cryogenic environments.
