Raman spectroscopic and theoretical study of liquid and solid water within the spectral region 1600-2300cm^-1

Area of Science:

• Physical Chemistry
• Spectroscopy
• Materials Science

Background:

• Water's unique properties are governed by its hydrogen bond network.
• Understanding the solid-state structure of water (ice) is crucial for various scientific disciplines.
• Raman spectroscopy is a powerful tool for probing molecular vibrations and structure.

Purpose of the Study:

• To investigate the changes in Raman spectra of water during the liquid-to-solid phase transition.
• To analyze the influence of hydrogen bonding on water molecule vibrations.
• To model and understand spectral anomalies observed in ice.

Main Methods:

• Experimental measurement of Raman spectra for liquid water and ice at varying temperatures.
• Computer analysis using a tetrahedral model for spectral changes.
• Quantum-chemical calculations (B3LYP/cc-pVTZ) for structure, vibrations, and Raman spectra.
• Analysis of hydrogen bond influence on bending vibrations.

Main Results:

• A decrease in the intensity of the bending vibration band was observed upon transition from liquid water to ice.
• An anomalously high intensity Raman peak near 2200 cm⁻¹ was detected in the solid phase (ice).
• Calculations supported the observed spectral changes and analyzed the role of hydrogen bonds.

Conclusions:

• The study elucidates spectral differences between water and ice, linked to hydrogen bond network rearrangements.
• Quantum-chemical modeling provides insights into the vibrational properties and Raman activity of water in different phases.
• Potential weakening of hydrogen bonds due to specific vibrational modes is considered.