Luminescence from irradiated butadiene solutions: fluorescence of allyl radicals?

Abstract

Solutions of butadiene and its derivatives show strong luminescence near 500 nm on warming after γ-irradiation at 77 K. Possible sources of the emission are radiative charge-transfer processes in the ion pairs, the excited dienes themselves and the radicals formed from them by addition of a hydrogen atom, although these species are not known to luminesce. The last assignment appears most probable, i.e. excitation following neutralisation of the corresponding carbanion. The mechanism of formation of these anions is not known: it is tentatively suggested that spur processes are involved.