Niro Ishikawa

Radicals in heavy ion-irradiated polyvinylidene fluoride

Abstract Heavy-ion irradiation-induced radicals in polyvinylidene fluoride films were examined using electron spin resonance (ESR) spectrometry. The films were bombarded by 79 Br 12+ (160 MeV), 35 Cl 9+ (150 MeV), 35 Cl 6+ (70 MeV) and 12 C 6+ (90 MeV) ions from a Tandem accelerator at 5.7 K and then measured at 77 K using ESR. Changes in the ESR spectrum produced by ion irradiation closely resembled that of γ-ray irradiation. With an increase in the ion fluence, the polyenyl-type radical predominates. The radicals reacted with O 2 to yield a peroxy radical when exposed to air at room temperature. The presence of oxygen-induced species was related to the etchability of the heavy ion latent track.

Selective T/H separation by NH3 laser multiple-photon dissociation of CTCL3

The multiple-photon dissociation (MPD) of CTCL3 and the selectivity of T/H separation were investigated using a pulsed NH3 laser, whose radiation contained a few lines depending on operating conditions. When Xe was added to chloroform, the dissociation rate of CTCL3 increased at chloroform pressures below 2 Torr as a consequence of the removal of multiple-photon absorption bottleneck by collisions with Xe. The dissociation rate of CTCl3 decreased monotonically with increasing chloroform pressure from 0.2 to 7 Torr. The depletion of CHCl3 was not observed within experimental errors. The lower limit of the tritium enrichment factor in photo-products produced by one pulse irradiation was 570 at chloroform pressure of 2 Torr.

Tritium separation by laser multiple-photon dissociation of CDTCl2/CD2Cl2 mixture

Abstract Selective multiple-photon dissociation of CDTCl 2 in CD 2 Cl 2 was studied using a TEA CO 2 laser. The dissociation rate of CDTCl 2 had a maximum value at 927 cm −1 (P (38) line) irradiation. The frequency agreed with the calculated ν 7 vibrational frequency (929 cm −1 ) of CDTCl 2 within the accuracy of the calculation. The tritium enrichment factor β prod was obtained to be 29 −15 +156 at 3 Torr total pressure and at 907.8 cm −1 irradiation.

Fluorination behaviors of the complexes of RbFUF4 and CsFUF4 systems

Abstract The reaction behaviors between some complex fluorides of MFUF 4 system (M = Rb or Cs) and fluorine were investigated. In all the cases, uranium was oxidized to hexa-valent state at the temperatures between 300 and 500°C and M 2 UF 8 type complex was formed, except for the cases of 3MF·UF 4 type complexes. In the fluorinations of 3MF·UF 4 , products with the composition of M 3 UF 9 were formed. A change in the stability of RbFUF 6 systems with RbF/UF 6 ratio was also investigated.

Effects of gamma rays on etching of heavy ion tracks in polyimide

Abstract It was found that exposure of polyimide, bombarded by heavy ions, to gamma rays in the presence of oxygen increased the emergence of etched heavy ion tracks. The degree of increase was larger for the lighter ions than for the heavier ions. The effect was remarkable only for the track etching rate and the large ratio of V t V g obtained. At doses of more than 4 × 108 rad the track etching rates converge to a certain value, regardless of the kind of ions. The presence of oxygen during gamma-ray exposure was considered to inhibit cross-linking and form some oxygenated compounds in the polymer that accelerate the dissolution of the tracks.

The formation of Rb2UF8 by fluorination of RbF·UF4

Abstract The complex Rb 2 UF 8 was obtained by fluorinating the known complex RbF·UF 4 at 400°C with fluorine gas which was diluted to 10% with nitrogen. The reaction was as follows: 2(RbF·UF 4 )+2F 2 → Rb 2 UF 8 + UF 6 . The valence of uranium in this complex was confirmed to be in hexa-valent state by observing the visible and near-IR absorption spectra. The IR spectrum was also obtained and two strong absorptions were assigned to UF stretching and FUF bending vibrations.

Kinetic Study of Tritium Exchange Reaction Between HTO and CHCl3

A kinetic study of the base catalyzed tiitium exchange reaction between HTO and CHCI3 and hydrolysis reaction of CHCl, was made undet conditions of coexistence of water and Chloroform phases. The hydrolysis and tritium exchange reactions were found to proceed predominantly in water phase. Rate constants for the hydrolysis of CHCI3 and the detritiation of CTCI3 were determined in the temperature ränge from 25.0° to 41.5°C. The equilibrium constants for the tritium exchange reaction were also determined and compared with the theoretical values calculated using isotopic reduced partition function ratios based on anharmonicity-corrected F-matrix for molecular vibrations. Tritium was found to be enriched in Chloroform at equilibrium.

Pyrohydrolysis Reactions of UF4, and UO2F2

This study was made for clarification of the pyrohydrolysis behaviors of UF4 and UO2F2. The progress of the reaction was measured by titrating the amount of produced hydrogen fluoride. When nitrogen was used as carrier gas of water, the pyrohydrolysis of UF4 proceeded at the temperatures of 350–400°C, and UO2+x (x≲0.3) was formed; the value of x decreased with the decrease of oxygen dissolved in the water. In the case of oxygen carrier gas, the pyrohydrolysis of UF4 formed U3O8-UO2F2 mixture as the reaction product in the above temperature region and the reaction was markedly retarded in the course because of lower rate in the pyrohydrolysis of UO2F2. The pyrohydrolysis of UO2F2 proceeded at a little [higher temperature of 450–500°C in both cases of nitrogen and oxygen carrier gas and α-UO3 was formed.

Elution of residual ions with etching of heavy ion-injected polyimide

Abstract The experiment was carried out to estimate the amount of residual ions after the etching of polyimide irradiated by heavy ions, where etching resulted in a channel of measurable depth in the polyimide. None of the analytical techniques presents each ion separately in etched polyimide containing heavy ions. Activation analysis was used for the irradiated polyimide to see how the injected ions were eluted into the solution by etching. When the irradiated polyimide was etched for only a little longer than the time needed to dissolve a selected range of incident ions, the bulk began subsequently to dissolve. The residual radioactivity in polyimide was found to fall below the limit of detection when the depth of the etched channel appeared 10% deeper than the expected value.