Fluorescence of jet-cooled naphthalene: Emission spectra, lifetimes and quantum yields

Fluorescence spectra of naphthalene, C10H8, were obtained in the laboratory under conditions which provide an appropriate simulation of the cometary c onditions: super-cooled gas phase molecules in a collision-free environment . Five spectra were recorded, the excitation energies ranging from 1422 to 5293 cm(-1) above the first electronic state S-1 at 32020 cm(-1). A compari son with previous jet-cooled naphthalene fluorescence spectra obtained by B eck et al. [1] and Hermine [2] shows that the former results are not consis tent with the present ones. Spectra obtained by Beck et al. show weaker int ensities at greater wavelengths compared to those obtained by Hermine and o urselves. We also measured the fluorescence lifetimes by recording the fluo rescence decay as a function of time after the excitation of the molecules by monochromatic lasers and deduced the fluorescence quantum yields. A synt hetic emission spectrum under solar irradiation is obtained for astrophysic al implications.