Nanosecond-Pulse Radiolysis of Aniline

Abstract

The nanosecond‐pulse radiolysis of pure aniline reveals two transient species absorbing at 3850 Å and 10 500 Å or higher. Each transient shows a rapid initial first‐order decay ${\mathrm{(t}}_{\text{1/2}}\text{\hspace{0.17em}=\hspace{0.17em}62.5\hspace{0.17em}±\hspace{0.17em}1.5}\mathrm{nsec})$ and a long‐lived (tens of microseconds) decay. In the presence of electron scavengers, the long‐wavelength transient is removed, and yields of the negative ions of biphenyl and pyrene are observed with plateau yields of $\text{G\hspace{0.17em}=\hspace{0.17em}0.95\hspace{0.17em}±\hspace{0.17em}0.05}$ . At high concentrations of biphenyl or pyrene, the decay characteristics of the negative ions are identical with those of the species in pure aniline at 3850 Å. Scavenging studies using both positive and negative ion scavengers show that the two transients present in pure aniline are the solvent positive ion (3850 Å) and the solvated electron (10 500 Å) in aniline. The extinction coefficients of $\phi {\mathrm{NH}}_2^{+}$ and $e_{\mathrm{aniline}}^{-}$ determined from ionic scavenging results are 12 050 and 3550 cm²/mole, respectively. The formation of excited states of naphthalene, anthracene, and 1, 2‐benzanthracene are observed, and the results clearly show that, where solvent–solute charge‐transfer reactions are possible, they lead to the production of ∼20% of the total triplet yields.