SITE-DEPENDENT VIBRATIONAL RELAXATION OF $N_{2} A {^{3}\Sigma (\upsilon' \leq 6)}$ IN SOLID ARGON

$^{1}$D. S. Tinti and G.W. Robison, J. Chem. Phys. 49, 3229 (1968).The Vagard-Kaplan A ${^{3}\Sigma_{u}}^{+}\rightarrow X {^{1}\Sigma_{g}}^{+}$ omission system of $N_{2}$ in solid argon has been excited by 10 keV electrons, at $N_{2}$ concentration in the 0.03 to 38 range, and at temperatures of T= 5K and 24K. The spectrum consists of doublet bands originating in vibrational levels $v^{\prime} \leq 6$. Whereas Tinti and $Robinson^{1}$, using X-ray excitation, measured exponential decays of the $\upsilon' \leq 5$ levels which indicate a vibrational cascade $\upsilon' = 6 \rightarrow 5 \rightarrow 4 \rightarrow 3 \rightarrow 2 \rightarrow 1$ with rates of the individual steps depending on $\upsilon'$, on $N_{2}$ concentration, and on temperature. Moreover, the two peaks of the spectral doublets belong to two separate cascading systems with very different cascading rates. The effect is presumably due to site-dependent vibrational energy transfer to another molecular species