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

Publisher Website
Google Scholar
Abstract
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 this state remains D2h.