Knowledge Bank

The collision-induced first overtone band of $H2-Ar$ gas mixtures was observed at 160 K and pressures up to 1700 atm. Previous studies at low densities showed the enhancement by argon of the three single $H2$ overtone transitions $Q2(1)$, $S2(0)$ and $S2(1)$. The present work shows that with a constant $H2$ density and increasing argon densities the double $H2$-transitions $Q1(1,0)+Q1(1)$ and $Q1(1,0)+S1(1)$ begin to appear at argon densities of $\sim $400 amagat. The results have two interesting features: (1) the intensities of the double $H2$ transitions increase more rapidly with Ar density than the single $H2$ transitions, (2) the half-widths of the double transitions are $ \sim 25 %$ less than the half-widths of the single $H2$ transitions. The implication of these results for the molecular dynamics of high density studies will be discussed.