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 Q1 lines and the rotational S0(0) and S0(1) lines were measured at a series of gas densities with a high-dispersion grating spectrograph. The perturbations in ωe and B0 are represented as power series in the density with linear and quadratic terms. The linear term for Δω0 is positive for H2–He, slightly negative for H2, and more negative for H2–A. These results are discussed in terms of an anharmonic oscillator model for the H2 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.