THE RAMAN EFFECT IN GASEOUS HYDROGEN AT HIGH PRESSURES

Abstract

The Raman spectrum of hydrogen as a pure gas and in mixtures with helium and argon was studied in the pressure range 100 to 2000 atmospheres at room temperature. Frequency shifts and half-widths of the vibrational Q 1 lines and the rotational S 0 (0) and S 0 (1) lines were measured at a series of gas densities with a high-dispersion grating spectrograph. The perturbations in ω e and B 0 are represented as power series in the density with linear and quadratic terms. The linear term for Δω 0 is positive for H 2 –He, slightly negative for H 2 , and more negative for H 2 –A. These results are discussed in terms of an anharmonic oscillator model for the H 2 molecule, a polarizability model for the dispersion forces, and the classical pair distribution function. The rotational lines show additional perturbations which are not accounted for in this treatment.