Gamma radiolysis of 3-methylpentane and ethanol glasses containing triphenylamine

Gamma irradiation of a 3-methylpentane (3MP) glass containing triphenylamine (TPA) at 72–74K produces the trapped electron (e_3MP⁻) and another negative species (e_TPA⁻). Like e_TPA⁻ absorbs in the I.R. with a peak at 1.6 μm. In contrast with e_3MP⁻, e_TPA⁻ is not bleached by 1.9 μm light, has a narrower absorption band, and exhibits a broader E.S.R. singlet with ΔH_{ms = 6.6 G}. At 72K, the 100 eV yield, G(e_TPA⁻), increases with increase in TPA concentration and has the value 1.3 at 10⁻² mol dm⁻³ TPA while G(e_3MP⁻ decreases from 0.4 in neat 3MP to 0.1 at 10⁻² mol dm⁻³ TPA. Gamma irradiation of an ethanol glass containing TPA at 77K does not produce an infrared absorption but produces peaks at 440 and 410nm in addition to the trapped-electron peak at 540nm. The peaks at 440 and 410nm are attributed to TPA⁻ because absorbance at these peaks increases with increase in TPA concentration and that at 540nm decreases. The totality of the results for alcohol and 3-MP glasses suggests that e_TPA⁻ is an electron in a trap similar to that of e_3MP⁻ but modified by the presence of a TPA molecule whose positive nitrogen end is oriented toward the electron.