Knowledge Bank

Hundreds of level-to-level Rotational Energy Transfer (RET) rate constants have been measured for the process [Na^{}{2}(j{i}) + X + Na^{}{2}(j{1}+\Delta ) + X] Where $ji$ is the initial rotational quantum number, $\Delta$ is the change in rotational quantum number and X is Xe, Kr, Ar, Ne, He, $H2,N2$, and $CH4$. By using the technique of Light-Induced Fluorescence with a single-mode dye laser we can systematically vary the initial rotational quantum number j over the range 4 to 100. The high sensitivity of our apparatus allows us to make accurate (15% error) measurements of rate constants for collisions with $|\Delta |$ as high as 28 under low pressure conditions such that less $than.4$ collisions occur per radiative life time. We have used this new set of data as a testing aground for several fitting laws which represent the entire rate constant matrix $k(ji\to jf)$ with two or three variable parameters. The most successful fitting law, ECS-P, combines the Energy Corrected Sudden (ECS) scaling, law which represents the rate constant matrix in term of the $k(jf\to 0)$ column, with a power (P) $law2$ for $k(jf\to 0)=a[jf\to 1)]-1$.