Relative Dipole Moments of Excited Singlet and Triplet States in Molecules

Abstract

AbstractThe availability of experimental values of molecular dipole moments in electronically excited states suggests the desirability of establishing some general principles. Three such principles are proposed, as a means of explaining the observed values of the dipole moment in corresponding singlet and triplet states, where the relevant molecular orbitals are very similar. The general conclusion is that we shall usually expect μGS ‐ μT to be larger than μGS ‐ μS, where μGS, μT, μS are the dipole moments in the ground state, the excited triplet and singlet states respectively. The principles are illustrated by specific reference to NF, CO, BeO, formaldehyde, methylene and azulene. Some difficulties arise with larger molecules, and also when configuration interaction plays an unusually important rǒle.