Paramagnetic Resonance of Alkyl Radicals from Dissociative Electron Attachment in ggr;hyphen;Irradiated Organic Glass

摘要

The radicals CH3middot;, CH3CH2middot;, CH3CH2CH2middot;, (CH3)3Cmiddot;, (CH3)3CCH2middot;, and C6H5Cdot;HCH3have been identified by EPR in ggr;hyphen;irradiated dilute solutions of the corresponding halides in 3hyphen;methylpentane at 77deg;K. For 0.4 mole CH3I,G(CH3middot;)=1.2. Methyl radicals disappear by some firsthyphen;order rate process for whichk=4.6times;10minus;4secminus;1. Other radicals did not decay measurably under similar conditions. The results are consistent with the mechanism of dissociative thermal electron attachment, RX+eminus;rarr;Rmiddot;+Xminus;, which is an efficient, selective process whenever the electron affinity of X exceeds the bond dissociation energy of Rmdash;X.