Spectroscopic investigations in molecularly organized solvent media. part 4. Effect of cosurfactant on the ability of the cetylpyridinium cation to selectively quench fluorescence emission of alternant versus nonalternant polycyclic aromatic hydrocarbons

Fluorescence behavior is reported for 12 alternant and 15 nonalternant poly cyclic aromatic hydrocarbons (PAHs) dissolved in aqueous micellar cetyltrim ethylammonium bromide (CTAB) + cetylpyridinium chloride (CPC), Brij-35 + CP C and sodium dodecylsulfate (SDS) + CPC mixed surfactant solvent media. The three cosurfactants studied contain a cationic, nonionic and anionic headg roup, respectively. Experimental measurements indicate that the cetylpyridi nium cation selectively quenches fluorescence emission of alternant PAHs. E mission intensities of nonalternant PAHs, with a few noted exceptions, rema in essentially constant, irrespective of both CPC concentration and cosurfa ctant headgroup charge.