Knowledge Bank

In very dilute expansions, 0.2% $N2O$ in Ar, dimer bonds of 1282 and $2228cm-1$ were observed corresponding to the $\nu 1$ and $\nu 2$ stretches of the monomer. As an example, the $\nu 1$ region spectra are shown in the figure for various dilutions. In the dimer, the NO stretch frequency is reduced and the NN stretch frequency is increased consistent with a staggered paralled configuration with the O atoms towards the centre. The dimer bond at $2228cm-1$ is shifted $+5cm-1$ while the $Ar-N2O$ complex bond origin shift is only $+0.1509cm-11$ ``Cluster bands'' (we have no means of determining the cluster size) corresponding to 6 bonds of the monomer were readily observed in rich mixtures. $-Q-100\%N2O$ at 1165, 1296, 2246, 2467, 2578, and $3506cm-1$. For all three bonds $2\nu 2.\nu 1$, and $\nu 3$ observed here and in the crystal, the cluster shift is larger and in the same direction. In $SF\ast \ast -Arclusters3$, a sharp peak appeared in the linewidth against size for clusters around $n=14$ which suggested a phase change. Such a peak was not observed here. Rother, the linewidths decreased monotonically with richer mixtures (larger clusters) suggesting a structure getting more and more rigid, as in the high pressure range of the $SF\ast \ast$ work. $(N2O)2$ linewidths were in the range $2-3cm-1$. Helium as a carrier gas gave the same results although clustering was more pronounced in Argon.