Knowledge Bank

Although numerous experiments have been conducted on the collisional quenching of electronically excited molecules, the quenching process is still poorly understood in terms of deactivation paths, energy gap size and propensity rules. In many cases, the analysis of purely” electronic deactivation is made difficult because of perturbations between the pertinent electronic states. A two laser, double resonance technique has been used as a direct probe of collision induced electronic energy transfer from selectively excited states of molecular nitrogen. Because nitrogen is homonuclear the appropriate states have no perturbations between them and purely” electronic transfer properties can be deduced. In the case of the nitrogen ion, J specificity is observable even for an energy gap of greater than $1500cm-1$ with a rate comparable to rotational energy transfer in the initially populated state. In addition, the electronic transfer due to collisions with helium atoms appears to follow optical like propensity rules.