ESR and ENDOR study of x-irradiated single crystals of β-alanine at room temperature

Abstract

Three radicals have been identified in the room temperature ESR spectra of x-irradiated single crystals of β-alanine (N+H3CH2CH2CO−2). ENDOR spectra from one radical exhibit hyperfine coupling to 1 α-proton (Axx=−33.12, Ayy=—20.68, Azz=−10.50 G) and 2 β-protons [Aiso(Hβ1) =13.24 G, Aiso(Hβ2) =4.89 G]. From the anisotropic nature of the α-proton coupling it has been determined that these splittings arise from a N+H3CH2ĊHCO−2 radical. It has been shown that this radical is the decay product of the unstable low temperature oxidation product. A second room temperature radical, N+H3CH2CH2Ċ=0, has been shown to be a decay product of the primary reduction product. A minor room temperature product has been tentatively identified as a ĊH2–CH2–R radical.