Knowledge Bank

The recent interest in the photochemistry of carbonyl compounds has prompted an investigation of radiationless transitions involving the lower excited states of these compounds. These include $\pi ,\pi \ast ;n,\pi \ast$; and possibly n, $o\ast$ singlet and triplet states as well as the ground state. Using formaldehyde as a prototype the various internal conversion and intersystem crossing transition probabilities are estimated from the magnitude of the intramolecular vibronic and spin-orbit perturbations which mix the zeroth order initial and final state electronic wave functions.