Electron Spin Resonance of γ-Irradiated Sodium Citrate Pentahydrate and Pentadeuterate

Abstract

An analysis of the electron spin resonance spectra of γ-irradiated single crystals of sodium citrate pentahydrate and sodium citrate pentadeuterate, deuterated by exchange with deuterium oxide, indicates that two long-lived radicals are present in both the protonated and deuterated citrates. One radical is of the form { ĊH–COONa –HO–C–COONa – CH2–COONa}·5H2O,with principal values of the proton hyperfine tensor of −91.1, −54.2, and −36.7 Mc/sec. The second radical gives a triplet with relative intensities 1:2:1 and splittings of 16 and 15 Mc/sec along the [100] and [001] axes of the crystal, respectively, and a quartet of lines of equal intensity with splitting of 21.5 and 28.0 Mc/sec along the [010] axis of the crystal, due to the interaction of two protons with the unpaired electron. The radical is possibly of the form { CH2–COONa –·O–C–COONa – CH2–COONa}·5H2O,with the unpaired electron coupling with one proton of each methylene group.