AbstractFluorescence measurements have been used to follow the build‐up of photoproducts during the direct and benzophenone‐sensitized irradiation of the title compounds 1‐IN, 1‐BrN, and 1‐ClN (HN = naphthalene). Compounds 1‐IN and 1‐BrN react by homolytic dissociation through their lowest triplet and singlet excited states, respectively. Compound 1‐ClN doesnotundergo C–Cl bond fission, except through electron transfer in the presence of an amine A,In the absence of this electron transfer, 1‐ClN reacts only through substitution and