Related Experiment Video
Updated: Jul 19, 2026

Methane Hydrate Crystallization on Sessile Water Droplets
Published on: May 26, 2021
Application of the independent molecule model to elucidate the dynamics of structure I methane hydrate
1Yatsushiro National College of Technology, Yatsushiro 866-8501, Japan. yoshioki@as.yatsushiro-nct.ac.jp
Abstract:
Raman spectroscopy has exhibited the C-H stretch (A1 mode) frequency nu1 of hydrated methanes at 2915 cm(-1) for the 5(12) cage and 2905 cm(-1) for the 5(12)6(2) cage. These values are lower than the frequency of 2916.5 cm(-1) in gaseous methane. In this paper, we theoretically examine the Raman spectra observed in methane hydrate by normal mode analysis using the independent molecule model. By a breakdown of the symmetry, the four frequencies in modes A1, E, T2 and T2 observed in gaseous methane are separated into nine frequencies in the hydrate. It is necessary to consider the anharmonic potential energy within methane and hydrogen bonding between methane hydrogen and water oxygen in order to get a result in qualitative agreement with experiment. The frequency in the 5(12)6(2) cage is shifted downward in comparison to the one in 5(12), and the frequencies in the both cages are also shifted downward compared with the frequencies in gas. Calculations are also reported for the isotopic methane (CD4, 13CH4) hydrates.
Related Concept Videos
Hybridization of Atomic Orbitals I
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
Inductive Effects on Chemical Shift: Overview
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
Molecular Models
Newman Projections
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.

