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Weak fluorescence from CS2 vapour excited in the 200-220 nm region has been observed between 220 and 360 nm, with a maximum quantum yield of -From the corrected fluorescence excitation spectrum, the variation in fluorescence quantum yield with excess energy was determined and shown to decline by an order of magnitude over the wavelength range 220 to 200nm. This decrease was attributed to the increase in importance of photodissociation with increasing photon energy.

The photodissociation of a-naphthol in liquid solutions was studied by flash photolysis. The transient absorption spectra in n-hexane, isooctane and carbon tetrachloride solutions decay bimolecularly and are attributed mainly to the a-naphthoxyl radical; the spectra obtained on adding proton acceptors Et20, dioxan or THF to n-hexane are different and decay unimolecularly ; they are assigned to a-naphthol triplet-triplet transitions. Results with added acetophenone as triplet energy donor to excite a-naphthol to the triplet state directly, with piperylene as triplet quencher, and with varying flash intensity show that radical formation proceeds monophotonically from the lowest triplet state of a-naphthol. Addition of Et20 to n-hexane solutions reduced radical formation but enhanced triplet formation and lifetime ; these results along with a kinetic analysis suggest that photodissociation is suppressed by hydrogen bonding of txiplet a-naphthol to proton acceptors such as EtzO.The transient absorption spectra observed on irradiation of hydroxyl derivatives of benzene and naphthalene in solution can be attributed to the triplet-triplet (T-T) absorption of the starting molecules and/or to absorption from the ground state of the neutral free radicals produced by fission of the fl bond of the side chain, i.e., Porter and coworkers 2 *