COLLISIONAL BROADENING AND SHIFTING OF THE PURE ROTATIONAL RAMAN LINES S(0)(J=0-4) OF H-2 AT ROOM-TEMPERATURE

The pressure broadening and shifting, of the S0(J = 0-4) pure rotation al Raman lines of normal hydrogen, have been determined from 1 to 35 a magat units of density, at 29.8-degrees-C. Over the range of densities explored, the width and shift of the lines are functions of the densi ty. Our precise results May be reconciled with earlier measurements at higher densities by adding a term cubic in the density for the widths and quadratic in the density for the shifts. it is argued that the pr esent results are safely within the impact regime and may be compared with calculations when they become available. The accuracy obtained is about 0.2 MHz per amagat (congruent-to 0.5%), for the broadening, and ranges from 0.1 to 0.3 MHz per amagat (congruent-to 1-4%) for the shi fting coefficients. An analysis of the results indicate that it may be possible to combine the shifts of the pure vibrational and the pure r otational Raman lines to disentangle the contributions of the isotropi c and anisotropic intermolecular forces to the perturbation of molecul ar spectra. Departures from linear broadening and shifting, at high de nsity, are discussed.