Knowledge Bank

Electronic band origins and vibrational band spacings in excited electronic states have been compared for the approximately 230 electronic transitions of diatomic molecules which have been observed both in the gas phase and in rare-gas or nitrogen matrices. With few exceptions, valence transitions and the associated vibrational band spacings are shifted by less than about 1% in neon matrices. Somewhat larger shifts, often to longer wavelengths, result from isolation of the molecule in a heavier rare-gas or a nitrogen matrix. The perturbation of Rydberg transitions by the matrix and the effects of charge-transfer interaction with the matrix will be discussed.