Abstract:
Additional results on the effect of additives on the product yields in the vapour-phase photolysis of trans-but-2-ene and cis-pent-2-ene are reported. They confirm, extend and reconcile our previous results with those of Chesick. The main photoreaction could be quenched by all additives at both wavelengths; at 203 nm, and with some additives at 185 nm, quenching was accompanied by photoisomerization. The effects can be correlated with the two states, Rydberg and V(π→π*), which are excited at the two wavelengths. Collisional deactivation of the V state results in photoisomerization while when the R state is deactivated no isomerization occurs. Apparently there is no ready collisional interconversion of the R and V states.
