Excited States of the Naphthalene Molecule. II. Further Studies on the First Singlet—Singlet Transition

The polarized fluorescence and absorption spectra of naphthalene and naphthalene d‐8 have been studied under the conditions described in Part I for the absorption of ordinary naphthalene. When all the data are examined and compared with the Raman assignments, a complete set of totally symmetric fundamentals for the first excited state can be found. The b1g‐modes which bring about the short‐axis absorption of naphthalene may be combinations rather than fundamentals. The short‐axis fluorescence shows that b1g‐combinations rather than fundamentals bring about vibrational‐electronic interaction, yet most of the short‐axis fluorescence has ag‐origins. This latter fact is not completely understood, although partial explanations are offered. It is deduced from the vibrational pattern of the absorption and emission spectra that a change in length of the central link and a slight expansion of the rings are the most important geometry changes occurring in the transition to the first excited state. The symmetry in t...