Knowledge Bank

The fundamental infrared bands of $H2$ and $D2$ in dilute solutions $(\sim 1:100)$ in liquid and solid argon have been studied in a 20 cm absorption path length at $\sim 180\circ C$. An analysis of the frequencies of the $Q,S(0)$ and $S(1)$ groups of lines for the $H2-Ar$ solid solution has already been given on the basis of a cell model involving an $H2$ molecule on a substitutional lattice $site;1$ the frequencies for the $D2-Ar$ solid solution are in substantial agreement with this analysis. The spectra of the liquid solutions differ from those of the solid solutions in two important respects: (a) they resemble very closely the collision-induced spectra of the corresponding gas mixtures, and (b) the integrated intensities are about four times greater tha those for the solid. Thus, although the cell model is certainly justified for the solid, it does not appear to be appropriate for the liquid as has been postulated by Ewing and $Trajmar2$ and by Bulanin and $Tonkov3$. The induced spectrum of hydrogen in liquid solutions seems rather to emphasize the collisional aspects of the molecular motion in liquids, as might be expected from the relatively short ranges of the interactions involved in the induction process. $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ R.J. Kriegler and H.L. Welsh, Can. J. Phys. 46, 1181 (1968). $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ G.E. Ewing and S. Trajmar, J. Chem. Phys. 41, 814 (1964). $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ M.O. Bulanin and M.V. Tonkov, Vesn. Leningrad Univ., Ser. Fiz, i Khim., No. 22, 41 (1966).