Author Keywords: Radiation detection; Long-lasting phosphor; Luminescence; Temperature dependence; Fade-out effect 相似文献
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排序方式: 共有1752条查询结果,搜索用时 15 毫秒
71.
Correlation between Chemical Dopants and Topological Defects in Catalytically Active Nanoporous Graphene 下载免费PDF全文
72.
Daichi Yazaki Tokuhisa Kawawaki Daisuke Hirayama Masanobu Kawachi Kosaku Kato Sota Oguchi Yuichi Yamaguchi Soichi Kikkawa Yoshiya Ueki Sakiat Hossain D. J. Osborn Fumihiko Ozaki Shunsuke Tanaka Jun Yoshinobu Gregory F. Metha Seiji Yamazoe Akihiko Kudo Akira Yamakata Yuichi Negishi 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(34):2208287
For the realization of a next-generation energy society, further improvement in the activity of water-splitting photocatalysts is essential. Platinum (Pt) is predicted to be the most effective cocatalyst for hydrogen evolution from water. However, when the number of active sites is increased by decreasing the particle size, the Pt cocatalyst is easily oxidized and thereby loses its activity. In this study, a method to load ultrafine, monodisperse, metallic Pt nanoclusters (NCs) on graphitic carbon nitride is developed, which is a promising visible-light-driven photocatalyst. In this photocatalyst, a part of the surface of the Pt NCs is protected by sulfur atoms, preventing oxidation. Consequently, the hydrogen-evolution activity per loading weight of Pt cocatalyst is significantly improved, 53 times, compared with that of a Pt-cocatalyst loaded photocatalyst by the conventional method. The developed method is also effective to enhance the overall water-splitting activity of other advanced photocatalysts such as SrTiO3 and BaLa4Ti4O15. 相似文献
73.
Yan Wu Daisuke Tozawa Tatsuya Ito Tsutomu Tada Keitaro Hitomi 《Journal of Nuclear Science and Technology》2013,50(3):320-327
A crown ether loaded resin was prepared by successive impregnation and fixing the 4′,4′(5″)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) and its molecule modifier, 1-dodecanol, onto the porous silica/polymer composite support (SiO2-P particles). The characterization of DtBuCH18C6 loaded resin was examined by thermal gravimetry and differential thermal analysis and electron probe microanalysis. The adsorption behavior of Sr(II), Cs(I), Ru(III), Pd(II), La(III), Nd(III), Sm(III), Gd(III), Zr(IV), and Mo(VI) was investigated by the batch method. Furthermore, the column test for Sr (II) was performed. The batch experiments were carried out by varying the shaking times, HNO3 concentration, and initial concentration of metal ions. A relatively large K d value above 182 cm3/g for Sr(II) was obtained in the presence of 3 M HNO3. In contrast, the K d values of Cs(I), Ru(III), Pd(II), La(III), Nd(III), Sm(III), Gd(III), Zr(IV), and Mo(VI) were considerably lower than 10 cm3/g. The adsorption of Sr(II) was found to be controlled by chemisorption mechanism, and followed a Langmuir-type adsorption equation. The breakthrough curve of Sr(II) had S-shaped profile, and the elution percentage was estimated to be 99.9% by using the eluent of H2O. 相似文献
74.
This study describes a basic theory for reconstructing pure Raman signals of materials composing a multilayer sample from Raman spectra obtained using two types of miniaturized Raman probes. An illustrative example is demonstrated using a multilayer system of samples composed of the transparent plastics polymethylmethacrylate (PMMA) and polyethylene (PE) as a model of thin-layered biomedical tissues. When the same region of an object is measured using Raman probes with different focal properties, the Raman spectra provide different depth profile information depending on the level of light penetration. Thus, a detailed comparison of the spectra can provide an interesting opportunity to probe the differences between the layers. A simple analytic form is presented for reconstructing the pure Raman spectra of the embedded layer. The method applies an understanding of the Raman sampling volume in layered transparent materials to the interpretation of Raman spectra experimentally measured by multiple probes. The basic theory described here is necessary for the expansion of the technique to turbid media, such as biological samples, where light-scattering effects must be considered. The potential applications of the proposed method include material and catalyst subsurface probing through different embedded materials, such as assessment of silicon wafers, effective noninvasive screening for catalyst synthesis, and biomedical tissue research. 相似文献
75.
Koichi Ogawa Toru KobayashiFutoshi Kaibuki Tsutomu YamakawaTatsuya Nagano Daisuke HashimotoHideyuki Nagaoka 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2012,664(1):29-37
The aim of this study is to develop an energy-binned photon-counting (EBPC) detector that enables us to provide energy information of x-rays with a reasonable count statistics. We used Al-pixel/CdTe/Pt semiconductor detectors, which had an active area of 8 mm×144 mm and consisted of 18 modules aligned linearly. The size of a CdTe detector module was 8 mm×8 mm and the thickness of the CdTe crystal was 1 mm. Each module consisted of 40×40 pixels and the pixel size was 200 μm×200 μm. We applied the bias voltage of −500 V to the Pt common electrode. The detector counted the number of x-ray photons with four different energy windows, and output four energy-binned images with pixel depths of 12, 12, 11 and 10 bits at a frame rate of 1200 Hz (300 Hz×4 energy bins). The basic performance of the detector was evaluated in several experiments. The results showed that the detector realized the photon counting rate of 0.4×106 counts/sec/pixel (107 counts/sec/mm2), energy resolution 4.4% FWHM at 122 keV. The integral uniformity of the detector was about 1% and the differential uniformity was about 1%. In addition, the image quality was examined with a resolution chart and step-wedge phantoms made of aluminum and polymethyl methacrylate. And we compared the quality of an acquired image with that acquired with an energy integration detector. The results of these experiments showed that the developed detector had desirable intrinsic characteristics for x-ray photon counting imaging. 相似文献
76.
The techniques for fabricating a hollow optical fiber with an inner silver layer and a cyclic olefin polymer (COP) layer have been improved to reduce the surface roughness of these two layers. The loss spectrum was thereby drastically reduced over a wide wavelength range, from visible to near infrared. Optimization of the COP layer thickness resulted in low loss simultaneously at several key laser wavelengths. Infrared hollow fiber with low loss was developed for Er:YAG and Nd:YAG lasers. It can also deliver green and red pilot beams with low loss. Use of this fiber in therapeutic and pilot lasers should prove useful for research and development in laser medicine. 相似文献
77.
We propose sealing techniques for medical hollow fibers to protect the inner surface of fibers from debris or water that scatters from targets. First, hollow fibers are sealed with a film of polymer that is easily formed by use of a dipping technique. The transmission loss of 20-microm-thick sealing film was 0.2 dB for Er:YAG laser light, and the maximum energy that is available for the film was 180 mJ. Second, a sealed glass cap was applied to the output end of hollow fiber. The silica-glass cap with a wall thickness of 400 microm shows a transmission loss of 0.5 dB and was not damaged by radiation of 400-mJ energy pulses. 相似文献
78.
Munehiko Kowatari Daisuke Koyama Yoshiyuki Satoh Kouichi Iinuma Shunsuke Uchida 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2002,480(2-3):431-439
The temperature dependence of luminescence from a long-lasting phosphor (LLP), SrAl2O4 : Eu2+,Dy3+, exposed to ionizing radiation has been measured to understand the LLP luminescence mechanism. Evaluation of the decay constants of the LLP exposed to -, β- or γ-rays at temperatures from 200 to 390 K showed that the decay constant is divided into four components ranging from 10−4 to 10−1 s−1 with activation energies of 0.02–0.35 eV.
Total luminous intensity from the LLP with changing irradiation temperature has its maximum value around the room temperature. Irradiation at elevated temperature (390 K) has the total luminescence pattern with monotonous decrease as temperature rises. As a result of evaluating the temperature dependence of luminescence, the luminescence mechanism is considered as follows:
79.
Determining surface orientations of transparent objects based on polarization degrees in visible and infrared wavelengths 总被引:1,自引:0,他引:1
Miyazaki D Saito M Sato Y Ikeuchi K 《Journal of the Optical Society of America. A, Optics, image science, and vision》2002,19(4):687-694
Techniques for modeling an object through observation are very important in object recognition and virtual reality. A wide variety of techniques have been developed for modeling objects with opaque surfaces, whereas less attention has been paid to objects with transparent surfaces. A transparent surface has only surface reflection; it has little body reflection. We present a new method for obtaining surface orientations of transparent surfaces through analysis of the degree of polarization in surface reflection and emission in visible and far-infrared wavelengths, respectively. This parameter, the polarization degree of reflected light at the visible wavelengths, is used for determining the surface orientation at a surface point. The polarization degree at visible wavelengths provides two possible solutions, and the proposed method uses the polarization degree at far-infrared wavelengths to resolve this ambiguity. 相似文献
80.
Hyun Goo Ji Pablo Solís‐Fernndez Daisuke Yoshimura Mina Maruyama Takahiko Endo Yasumitsu Miyata Susumu Okada Hiroki Ago 《Advanced materials (Deerfield Beach, Fla.)》2019,31(42)
Monolayers of transition metal dichalcogenides (TMDCs) have attracted a great interest for post‐silicon electronics and photonics due to their high carrier mobility, tunable bandgap, and atom‐thick 2D structure. With the analogy to conventional silicon electronics, establishing a method to convert TMDC to p‐ and n‐type semiconductors is essential for various device applications, such as complementary metal‐oxide‐semiconductor (CMOS) circuits and photovoltaics. Here, a successful control of the electrical polarity of monolayer WSe2 is demonstrated by chemical doping. Two different molecules, 4‐nitrobenzenediazonium tetrafluoroborate and diethylenetriamine, are utilized to convert ambipolar WSe2 field‐effect transistors (FETs) to p‐ and n‐type, respectively. Moreover, the chemically doped WSe2 show increased effective carrier mobilities of 82 and 25 cm2 V?1s?1 for holes and electrons, respectively, which are much higher than those of the pristine WSe2. The doping effects are studied by photoluminescence, Raman, X‐ray photoelectron spectroscopy, and density functional theory. Chemically tuned WSe2 FETs are integrated into CMOS inverters, exhibiting extremely low power consumption ( ≈ 0.17 nW). Furthermore, a p‐n junction within single WSe2 grain is realized via spatially controlled chemical doping. The chemical doping method for controlling the transport properties of WSe2 will contribute to the development of TMDC‐based advanced electronics. 相似文献