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81.
82.
JIAO Yiming LONG Yongxing DONG Jiaqi GAO Qingdi WANG Aike LIU Yong 《核工业西南物理研究院年报(英文版)》2006,(1):121-122
The effects of trapped electrons on off-axis lower hybrid current drive (LHCD) in tokamaks are studied. The influence of the resonance regime on the current drive efficiency as well as the influence of trapped particle fraction on the current drive efficiency are emphasized. 相似文献
83.
A theoretical study is made on the mobile interstitial and mobile electron models of mechano-induced luminescence in coloured
alkali halide crystals. Equations derived indicate that the mechanoluminescence intensity should depend on several factors
like strain rate, applied stress, temperature, density of F-centres and volume of crystal. The equations also involve the
efficiency and decay time of mechanoluminescence. Results of mobile interstitial and mobile electron models are compared with
the experimental observations, which indicated that the latter is more suitable as compared to the former. From the temperature
dependence of ML, the energy gaps between the dislocation band and ground state of F-centre is calculated which are 0.08,
0.072 and 0.09 eV for KCl, KBr and NaCl crystals, respectively. The theory predicts that the decay of ML intensity is related
to the process of stress relaxation in crystals. 相似文献
84.
A comparative study ofγ-ray colouration and electrodeless discharge excitation is reported for NaF. New absorption bands and glow peaks were found.
These are shown to be characteristic of electrodeless discharge method of colouration. These are attributed to the multiple
types of defects. Further, it is shown that the process by which such defects are formed is strongly temperature dependant.
A tentative explanation for the peculiar characteristic of the electrodeless discharge excitation is put forth. The possibility
of exploiting these peculiarities for the study of certain properties of colour centres is pointed out. 相似文献
85.
Fine powder of KI was coloured in an electrodeless discharge. Due to quick bleaching of the F centres produced in this method,
it was possible to prepare the samples that were almost free from the F centres. High concentration of the electron deficient
centres could be produced, which were studied by measuring the diffused reflectance. A band at 354 nm is shown to be composed
of two overlapping bands. Further, growth of a band appearing at 265 nm is studied. Bleaching characteristics of the samples
are studied and it is shown that, similar to F centre bleaching, bleaching of these samples also proceeds in at least two
steps. The difference between two components of the bleaching curves is quite marked. Further it is showed that the components
are related to the presence of different absorption bands and appear at different stages of colouration. 相似文献
86.
A. A. Vorobiev K. P. Arefiev S. A. Vorobiev 《Applied Physics A: Materials Science & Processing》1974,3(3):241-243
The effect of electron beam irradiation on the positron annihilation in KCl, KBr, NaCl single crystals was investigated. The
narrowing of the angular correlation curves increases up to the saturation value with the absorbed radiation dose. The shape
of the received narrow components differs from the narrow component measured in the additively colored samples. This phenomenon
shows the considerable influence of the hole centres upon the positron annihilation in ionic crystals.
Paper presented at 3rd Internat. Conf. Positron Annihilation, Otaniemi, Finland (August 1973). 相似文献
87.
Summary A coating of silicone SE-54 on Chromosorb W has been converted to an analytically stable, immobilized stationary phase layer by cross-linking with an organic peroxide. Up to 10% by weight has been applied in this manner. Excellent high temperature qualities are exhibited, such as low bleeding and good base line stability, during typical analyses.Poly (2,6-dimethyl-p-phenylene oxide) has also been crosslinked as a surface coating on Chromosorb W with an organic peroxide. From 3 to 4% by weight has been immobilized in this way. The resultant packing material, following high temperature conditioning, has been examined for use as an adsorbent of trace substances, similar to the applications to which such adsorbents as Tenax GC have commonly been applied, e.g. trace analysis of air. It appears to exhibit satisfactory properties for this analytical purpose. 相似文献
88.
The present paper describes an automated system for preparative gas chromatography with glass capillary columns, controlled by a microprocessor. The effluent from the capillary column is divided by a pneumatically controlled splitter and any desired split ratio between traps and detector can be obtained. Moreover, a second pneumatic control allows instantaneous change-over to a different split ratio, thus minimizing loss of material during collection. The effluent containing the compounds of interest is passed through a multiple manifold and collected in coiled glass capillary traps. To ensure maximum trapping efficiency even for very small amounts of material, the inner walls of the capillary traps are wetted with a suitable solvent, which gives a quantitative recovery of micro- and nanogram amounts of material. After repetitive sampling, sufficient amounts of material can be obtained for NMR spectroscopy and possibilities exist to enrich trace components with the aid of a double column system. Two examples of such applications are given, employing mixtures of both synthetic and natural origin. 相似文献
89.
Yuri Pleskov Alik Tameev Valentin Varnin Irina Teremetskaya 《Journal of Solid State Electrochemistry》1998,3(1):25-30
The drift mobility of nonequilibrium holes injected in undoped polycrystalline diamond films was determined, by a transit-time
technique, as ca. 10−3 cm2/(V s). This hole mobility is three orders of magnitude lower than the “equilibrium” mobility in boron-doped diamond films
[0.1–1 cm2/(V s)], determined from the films' dc conductivity. This difference is explained by the effect of a nonequilibrium charge
carrier trapping during the carrier transport in polycrystalline diamond.
Received: 3 December 1997 / Accepted: 9 April 1998 相似文献
90.
Alkoxycarbonylpiperazine-2,5-diones are versatile precursors for the α-functionalisation of piperazine-2,5-diones. The alkoxycarbonyl group activates the α-carbon position to alkylation reactions and this provides a mild and selective method for the extension of the carbon framework of piperazine-2,5-diones. In addition, the alkoxycarbonyl group can be converted to the carboxy group, which in turn can be ‘deleted’ or manipulated for the installation of carbon and/or heteroatom substituents where desired, the latter via N-acyliminium chemistry. We also demonstrate that hydroxymethylpiperazine-2,5-diones complement carboxypiperazinediones as precursors for the generation of N-acyliminium ions. 相似文献