Katsuyuki Inabe

Effect of iron impurity concentration on kinetics order of thermoluminescent blue emission in MgO single crystals

Abstract Thermoluminescence has been measured for two kinds of MgO single crystals. The kinetics of the 94°C glow peak for the blue emission was found to be second order for a sample containing iron in low concentration, while 1.3-order for one appreciably in high concentration. The result was discussed in terms of the concentrations of the recombination and retrapping centers.

Photostimulable transparent NaCl:Cu single crystals for two-dimensional x-ray imaging sensors

Intense photostimulated luminescence (PSL) is observed, for the first time, in x‐irradiated NaCl:Cu single crystals. The intensity of PSL with a peak at 353 nm is linearly increased with increasing x‐ray absorbed dose over the wide range. This suggests that NaCl:Cu is useful as a material for two‐dimensional x‐ray imaging sensors in computed radiography utilizing PSL phenomenon. All the results obtained are consistent with the proposed emission mechanism of 353 nm PSL peak, based on the recombination of electrons released from the F centers with Cu2+ ions.

The Role of Cu+ in the Thermoluminescence of X-Irradiated NaCl

A detailed investigation of the thermoluminescence and the trapping centers related with the main glow peak centered at 327 K have been carried out. The luminescence center of the peak is confirmed to be the substitutional Cu+ ion, whereas those of the other peaks observed at higher temperatures are not related to it. The 327 K peak is ascribed to the electrons released from the F- centers, which are considered to be formed from the F centers by trapping the electrons released from Cu0 centers.

Optically stimulated luminescence in Cu-doped sodium chloride single crystal for a high-quality X-ray imaging sensor☆

Abstract An intense optically stimulated luminescence (OSL) has been observed, for the first time, in X-irradiated copper-doped sodium chloride (NaCl:Cu) single crystals. The intensity of the OSL peak at 353 nm is proportional to the optical density of the F centres that are created by X-ray irradiation. This suggests that NaCl:Cu is useful as a material for a two-dimensional X-ray imaging sensor in computed radiography utilizing the OSL phenomenon. A possible reaction responsible for the 353 nm OSL peak is also proposed, based on the recombination of Cu2+ ions with electrons released from the F centres.

Room temperature visible distributed-feedback colour centre laser

The distributed-feedback (DFB) colour centre laser is described. The DFB laser action at 680 nm is observed by pumping on LiF crystal containing F2 centres with the fringes formed by the interference of two coherent light beams.

Effect of Mechanical Factors on Fractoluminescence of KCl:Ca2+ Crystals after X‐Ray Irradiation at Room Temperature

Mechanical factors responsible for fractoluminescence intensity of X-ray irradiated KCl:Ca 2 + are investigated. The fractoluminescence intensity is found to be proportional to the third power of fracture load. This suggests that the fractoluminescence depends on the number of intersections of dislocations in the moving processes of the dislocation at the fracture.

Eu concentration dependence of photostimulated luminescence in X-ray or UV-ray irradiated KCl: Eu phosphor ceramics

Abstract Europium doped potassium chloride (KCl:Eu) phosphor ceramics for two-dimensional X-ray or UV-ray imaging sensor utilizing photostimulated luminescence phenomenon (PSL) were prepared. Investigation of Eu concentration dependence of the PSL in X-ray or UV-ray irradiated KCl:Eu phosphor ceramics was carried out. An intense PSL with a peak at about 420 nm was observed in 0.5 mol % Eu doped KCl phosphor ceramics which is fabricated by sintering at about 700°C in air.

Distributed-Feedback Color Center Lasers Using N2 Centers in KCl

We report on a distributed-feedback (DFB) color center laser based on N2 centers in KCl. A periodic grating with fringe spacings as fine as 440 nm was produced by means of a two-photon coloration process using two interfering beams. Coloration and photoaggregation processes and the DFB laser action can be availed by the fourth- and second-harmonic and the fundamental lines of a Q-switched Nd:YAG laser, respectively. The linewidth of the DFB output is less than 0.3 nm in the spectrally important 1300 nm region.

Optical Properties of Photostimulable Near IR Centers in BaFCl Single Crystals Produced by Two-Photon Excitation

The stable and photostimulable F-aggregate centers, besides the already established isolated centers, located in the near IR region in BaFCl single crystals are reported. These F-aggregate centers are producible by two-photon excitation and the production rate can be enhanced by monovalent doping like incorporating K+ in BaFCl. The F-aggregate centers in BaFCl have been characterised by their growth behaviour, room temperature stability, optical bleaching, emission and the temperature dependence of the PSL lifetimes. It is a first time demonstration as applied to BaFCl single crystals to produce F-aggregate centers more efficiently by using the fourth harmonic of a Q-switched Nd:YAG laser as compared to X-irradiation.

Photostimulated luminescence in alkali halides induced by excitation with ionizing radiation

Abstract The photostimulated luminescence (PSL) phenomenon induced in copper-doped sodium chloride (NaCl:Cu) and europiumdoped potassium chloride (KCl:Eu) phosphor crystals by excitation with ionizing radiation such as X-rays is studied. The emission mechanism of the PSL in both phosphor crystals is discussed in terms of the recombination of electrons optically stimulated from the radiation-induced F centers with the luminescence centers such as Cu 2+ in NaCl and Eu 3+ ions in KCl. The potentiality of both phosphor crystals as a material for two-dimensional X-ray imaging sensors utilizing the PSL phenomenon is also discussed.