Electron Traps in Irradiated Water–Ethylene Glycol Glass at 4 and 77°K

In order to study the mechanism of electron trapping in irradiated glasses of water–ethylene glycol mixture, they were subjected to γ rays and examined by optical absorption and electron spin resonance measurements at 4 and 77°K. Most trapped electrons formed at 4°K give an optical absorption band in infrared region around 1800 nm and a single-line electron spin resonance spectrum with the width of 3 G, while the trapped electrons formed at 77°K give an absorption band in visible region (λmax = 585 nm) and an electron spin resonance spectrum with the width of 15 G. By warming the glass to 77°K after the irradiation at 4°K, the trapped electrons transformed to those observed for the irradiation at 77°K. Results indicate that the nature of trapped electrons formed at 4°K is very similar to that of trapped electrons in irradiated nonpolar alkane glasses. Even in the polar glass of water–ethylene glycol, the orientation of molecular dipoles is not needed for the formation of electron traps at 4°K, where the molecular movements are highly restricted. By raising the temperature to 77°K, the molecular dipoles in the vicinity of trapped electrons orient favorably to deepen the traps. The yield of trapped electrons, for 100 eV energy absorbed, at 4°K is estimated to be larger than 0.6. However, it is possibly less than 2.0, the yield for the irradiation at 77°K.