Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa.

We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas.

Experimental and theoretical analysis of the rotational Raman spectrum of hydrogen molecules in clathrate hydrates.

The Raman spectra of H(2) and HD molecules in simple hydrogen and binary hydrogen-tetrahydrofuran clathrate hydrates have been measured at temperatures as low as 20 K. The rotational bands of trapped molecules in simple and binary hydrates have been analyzed, and the contributions originating from hydrogen molecules in the large cages have been separated from those in the small cages. A theoretical model, consisting in rigid cages enclosing interacting hydrogen molecules, has been exploited to calculate, on the basis of quantum mechanics, the Raman intensity of the rotational transitions for up to two interacting molecules in one cage.

Far-infrared absorption by collisionally interacting nitrogen and methane molecules.

Quantum line shape calculations of the rototranslational enhancement spectra of nitrogen-methane gaseous mixtures are reported. The calculations are based on a recent theoretical dipole function for interacting N(2) and CH(4) molecules, which accounts for the long-range induction mechanisms: multipolar inductions and dispersion force-induced dipoles. Multipolar induction alone was often found to approximate the actual dipole surfaces of pairs of interacting linear molecules reasonably well.