Takenobu Higashimura

Electronic Spectra of Trapped Electrons in Organic Glasses at 4°K

The optical absorption spectra of trapped electrons were observed in γ‐irradiated ethylene glycol–water, methanol, 10M NaOH, and MTHF at 4°K. The prominent infrared absorption bands were observed in ethylene glycol–water and ethanol glasses, while the bands in methanol, 10M NaOH, and MTHF glasses were similar in shape, slightly red shifted, to the bands for the radiolysis at 77°K. When the glasses were warmed to 77°K, the bands changed irreversibly into those for the radiolysis at 77°K, reducing the absorption intensity. The spectral changes at the intermediate temperatures between 4°K and 77°K were recorded for ethylene glycol–water and methanol cases. The results are interpreted by the molecular reorientation model proposed in the previous paper [T. Higashimura, M. Noda, T. Warashina, and H. Yoshida, J. Chem. Phys. 53, 1152 (1970)].

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...

Dosimetry of Atomic Bomb Radiation in Hiroshima by Thermoluminescence of Roof Tiles.

Thermoluminescence dosimetry is a powerful tool for obtaining the distribution of gamma dose, heretofore unknown, from the atomic bombs dropped on Hiroshima and Nagasaki. Roof tiles irradiated by the bombs show intense thermoluminescence, and the radiation dose for samples irradiated below 100 r by the bomb can be measured by this method.

Electronic spectra of trapped electrons in organic glasses at 4°K. 3-methylpentane, 3-methylhexane and methylcyclohexane

Abstract The spectra of e − t produced in 3-MP and MCH at 4°K were at longer wavelengths than those at 73°K, and shifted back to the same position as those produced at 73°K when the glasses were warmed to 73°K. The spectra in 3-MHX at 4 and 73°K were the same.

Electronic Spectra ot trapped electrons in organic glasses at 4°K: VI. Photobleaching ethanol

Abstract The absorption spectrum of e t - in ethanol is composed of three bands, suggesting the existence of various kinds of traps. The retrapping phenomenon and the increase of the Bz radical were observed after photobleaching e t - at 4°K, but not e s - . The photo-transition of e t - is a bound-free one, but that of e s - may be a bound-bound one.

Electron scavenging at very low temperature

Abstract Results of electron scavenging experiments for gamma irradiation at 4 K are reviewed. An anomalous increase in the scavenging efficiency at 4 K is discussed. Intermediate anions which have very short lifetimes at usual temperatures are very stable at 4 K. As an example of these anions, the optical absorption spectrum of the benzyl chloride anion is described.

Mössbauer effect in peroxidase

Mossbauer spectroscopy provides valuable information on the electronic configuration of heme-iron and the surrounding ligand field strength in heme-proteins complementary to that derived from magnetic susceptometry and electron spin resonance (ESR) spectroscopy. Quite recently, the method has been applied on some biological materials containing iron atom, and some investigations have been reported on heme-proteins such as hemoglobin, myoglobin, catalase and cytochrome c Gonser et al. 1964; Bearden et al. 1965; Lang and Marshall 1966; Caughey et al. 1966, but not yet on peroxidase. This communication presents an outline of the experimental results on Mossbauer effect in Japanese-radish peroxidase a (JRP-a) and some of its derivatives enriched artificially with 57Fe in order to obtain any information complementary to that derived from the ESR study of this enzyme Morita and Mason 1965.

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.