Paramagnetic Relaxation Study of Spatial Distribution of Trapped Electrons in Gamma-Irradiated Organic Glasses

Abstract

Paramagnetic relaxation characteristics of trapped electrons in γ‐irradiated glassy 3‐methylpentane (3‐MP) at 71°K, and triethylamine (TEA) and methyltetrahydrofuran (MTHF) at 77°K were studied by power saturation techniques. For MTHF and TEA the characteristicrelaxation time, (T 1 T 2 ) 1/2 , is constant with radiation dose at low doses and decreases at higher doses. For 3‐MP the relaxation time decreases even at low dose. Together with data on the total spin concentration the results are interpreted in terms of a ``spur'' model in which the radiation‐produced trapped electrons and radicals are trapped in clusters at low dose and constitute a nonuniform spatial distribution. According to this model the spur radius is 〉130 Å in 3 MP, 101 Å in TEA, and 63 Å in MTHF. These radii compare with 58 Å for trapped electrons in glassy methanol and 41 Å in glassy alkaline ice (10M NAOH). For all of these matrices the radius within which the electrons are trapped appears to increase with decreasing polarity of the matrix, and consequently radiation‐produced electrons appear to travel farther before being trapped in less polar matrices.