Electron trapping in alcohol clusters in γ-irradiated n-propanol–hydrocarbon glasses at 77 K

1981 ◽  
Vol 59 (18) ◽  
pp. 2803-2807 ◽  
Author(s):  
Masaya Ito ◽  
Toyoaki Kimura ◽  
Kenji Fueki

A study has been made of trapped electrons in n-propanol–hydrocarbon mixture glasses at 77 K by the optical absorption method. The yields of electrons trapped in alcohol clusters (ealc−) were measured for several γ-irradiated n-propanol–hydrocarbon glasses, where the yields of trapped electrons in these neat hydrocarbon glasses at 77 K are known to range from 0.015 to 1.1 G units. The results show that the yields of ealc– in the mixture glasses do not depend on the trapped electron yields in neat hydrocarbon glasses. Thus, it is concluded that electron migration from relaxed hydrocarbon matrix traps into alcohol clusters is not the major process for ealc− formation in the systems studied here. The major process for ealc− formation may be attributed to quasi-free electron scavenging by alcohol clusters and electron migration from unrelaxed hydrocarbon traps into alcohol clusters. Both ir-induced and isothermal changes in the ealc− yield have also been investigated. These investigations indicate that there is a correlation between the observed change in the ealc− yield and the matrix viscosity.

1983 ◽  
Vol 61 (12) ◽  
pp. 2799-2803 ◽  
Author(s):  
Naoto Okabe ◽  
Toyoaki Kimura ◽  
Kenji Fueki

Photoconductivity spectra of trapped electrons in γ-irradiated 3-methylpentane, 2-methylpentane, 3-methylheptane, and 3-methylpentane–methylcyclohexane (1:9 volume ratio) glasses at 77 K were measured. From the comparison of photoconductivity and optical absorption spectra in these systems we have obtained relative values of quantum efficiencies for a trapped electron in the ground state to be excited to the conduction band by photo-induced transition. For electrons stably trapped, we have measured the ranges of trap depths from the shallowest to the deepest in these systems.


1977 ◽  
Vol 55 (23) ◽  
pp. 3973-3977 ◽  
Author(s):  
Noriyuki Kato ◽  
Toyoaki Kimura ◽  
Kenji Fueki

Trapped electron yields were measured by means of optical absorption spectroscopy for a hydrocarbon glass γ-irradiated at 77 K in the presence of an external electric field. It was observed that the yield of trapped electrons increased in the presence of an external electric field as compared with that in the absence of an external electric field. The experimental results were analyzed theoretically and interpreted as due to overall effects involving changes in geminate recombination times which were caused by an external electric field.


1983 ◽  
Vol 61 (3) ◽  
pp. 553-557 ◽  
Author(s):  
Toyoaki Kimura ◽  
Kazuhiro Yasuda ◽  
Shigeki Fukuda ◽  
Kenji Fueki

An optical absorption study has been made on electrons [Formula: see text] trapped in alcohol clusters in γ-irradiated 1-propanol (PrOH) – 2,2,4-trimethylpentane (TMP) – 2,2-dimethylbutane (DMB), 1-butanol (BuOH) – TMP – DMB, and 1-pentanol (PnOH) –– TMP – DMB mixture glasses at 77 K. Hitherto electron transfer from the hydrocarbon region into alcohol clusters has been known to be a major process for [Formula: see text] formation in γ-irradiated alcohol–hydrocarbon glasses. However, in the present systems of PrOH–TMP–DMB, BuOH–TMP–DMB, and PnOH–TMP–DMB, this type of electron transfer was not observed and the [Formula: see text] formation was found to result only from the direct radiolysis of alcohols. In the alcohol concentration range lower than 0.2 electron fraction the yields of [Formula: see text] are less than those expected from the direct radiolysis of alcohols. The average number of alcohol molecules in a cluster in these systems is estimated to be four in the lower alcohol concentration range studied. The position of the absorption maxima for [Formula: see text] in these systems is constant within experimental uncertainties independent of alchohol concentration, which is consistent with the results of a semicontinuum model calculation.


2012 ◽  
Vol 1 (2) ◽  
pp. 149-153 ◽  
Author(s):  
M. P. Deshpande ◽  
M. N. Parmar ◽  
Nilesh N. Pandya ◽  
Sandip V. Bhatt ◽  
Sunil Chaki

1984 ◽  
Vol 62 (1) ◽  
pp. 64-68 ◽  
Author(s):  
Toyoaki Kimura ◽  
Kazunobu Hirao ◽  
Naoto Okabe ◽  
Kenji Fueki

Optical absorption and photoconductivity spectra of trapped electrons in -γ-irradiated 2,2,4-trimethylpentane (TMP)/2,2-dimethylbutane (DMB)/2-methyltetrahydrofuran (MTHF) mixture glasses at 77 K have been measured. It is found that the magnitude of the photocurrent increases with decreasing MTHF concentration, which is ascribed to the increase in electron mobility with decreasing MTHF concentration in TMP/DMB/MTHF systems. It is also found that the photoconductivity spectra shift to the lower energy side with decreasing MTHF concentration. Although the photoconductivity spectrum in the neat MTHF system is separated from the corresponding optical absorption spectrum, the spectrum becomes closer to the latter with decreasing MTHF concentration in TMP/DMB/MTHF systems. This result indicates that the extent of bound–free transitions increases relative to bound–bound transitions with decreasing MTHF concentration for the photon absorption process of trapped electrons in TMP/DMB/MTHF systems.


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