Tetsuo Warashina

Trapped Electrons Produced in Ethanol Glass at 4°K

Optical absorption and ESR measurements were carried out on et− produced in ethanol at 4°K. The same et− yield for γ radiolysis at 4 and 77°K indicates that electrons are stabilized in pre‐existing traps at 4°K where molecular dipoles remain unrelaxed. et− prior to solvation can be classified into two groups. One with λmax = 1500 nm, W1/2= 4 × 103 cm−1 and Δ Hpp = 5.5 ± 0.5 G is easily photobleached by the infrared light. The other with broad absorption band in the visible and Δ Hpp = 13.5 ± 1.5 G is not photobleached by the infrared light. The successive shift of the absorption spectrum to the higher energy side on warming is interpreted by the molecular reorientation mechanism. et− decay is observed during the solvation process, depending on time required for the solvation. The blue shift of the absorption spectrum on reducing the temperature is attributed to contraction of electron traps.

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 m...

ESR Spectra of Monoprotonated Semiquinone Radicals Formed during Photolysis of p-Benzoquinone and Its Methyl Derivatives

Proton hyperfine coupling constants of monoprotonated p-benzosemiquinone, durosemiquinone, 2,6-dimethyl-p-benzosemiquinone, 2,5-dimethyl-p-benzosemiquinone and methyl-p-benzosemiquinone radicals were determined from ESR spectra during photolysis of the corresponding quinones under identical conditions, i.e., in ethanol and at about 20 °C. By considering all these constants together, the ESR spectra were assigned and following results obtained: (1) the hydroxyl groups were at the oxygen atom further from the methyl substituents, (2) the coupling constant was generally −1.86–−1.65 G for the hydroxylic protons, (3) the absolute value of the coupling constant for both ring and methyl protons was in the range 0–0.7 G for ortho-positions and 4.3–5.2 G for meta-positions relative to the hydroxyl group, and (4) the hydroxylic proton of durosemiquinone had an exceptionally small coupling constant because of steric hindrance of the methyl groups. The temperature dependence of the coupling constants in p-benzosemiqu...

ESR study of trapped electrons produced in alkane glasses at 4 °K

In gamma irradiated 3‐MP, MCH, and 3‐MHX glasses, the same et− yields were obtained between 4 and 71°K, indicating that electrons are stabilized in pre‐existing traps prior to solvation. The linewidths were reduced on warm‐up of the glasses irradiated at 4°K and depended on the annealing time at 71°K, implying that the solvation occurs very slowly around 71°K. A comparative study of power saturation in 3‐MP and MCH suggested that the spurs formed at 4°K were spatially expanded compared to those at 71°K. The structural change of trapping sites caused by solvation was clearly reflected on the power saturation characteristics.

Sourcing of sanukite stone implements by X-ray fluorescence analysis

Abstract Both powder analysis and non-destructive analysis of original sanukite stones and sanukite implements were carried out by means of X-ray fluorescence spectrometry of a non-dispersive type. Fluorescence peaks of eight minor elements (K, Ca, Ti, Fe, Rb, Zr, Y and Sr) were obtained and ratios of peaks were used as indices of characteristics of the samples. Original stones taken from eight different sources in Western Japan showed large inter-source deviations of these ratios compared with intra-source standard deviations. Non-destructive analysis was carried out by a similar procedure and the effect of different shapes of the samples on these ratios was sufficiently small for the allocation. Sanukite implements excavated in seven archaeological sites were analysed without destruction and all but one sample were allocated to their sources.

Allocation of jasper archaeological implements by means of ESR and XRF

Archaeological jasper implements were allocated to their sources by the non-destructive techniques of ESR and X-ray fluorescence (XRF). Ratios of signal intensities in ESR and XRF spectra of jasper implements are compared with those from jasper samples taken from natural sources, and Hotellings T2 test is applied. Samples from archaeological sites around Tokyo prefecture are shown to have originated from Kasenzan (600 km from Tokyo) jasper and some samples from archaeological sites in Kobe city are from a source in Tamatani (100 km from Kobe). A sample found from the archaeological site in Awaji island is from Kasenzan (200 km from Awaji).

Sourcing of sanukite implements by X-ray fluorescence analysis II

Abstract Non-destructive analysis of sanukite stones of known source and sanukite implements was carried out by means of energy-dispersive X-ray fluorescence spectrometry. Attention was focussed on areas in middle-western Japan. Stone taken from four source districts was classified into nine different groups. More than a hundred implements obtained from thirty-six archaeological sites were allocated to their sources by means of Hotellings T 2 test.

A hole-tunneling model for positive charge scavenging in irradiated aliphatic halides

Abstract For positive charge scavenging, a model of hole tunneling from the cation to the neutral solute is proposed rather than the model of electron tunneling from the neutral solute to the cation.