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硫增感AgBr I T颗粒乳剂光电子行为研究 总被引:1,自引:1,他引:1
本文利用微波吸收相敏检测技术,同时获得了硫增感AgBrIT颗粒乳剂,在不同增感条件下自由光电子和浅俘获光电子的时间衰减曲线,分析了不同的硫增感产物的陷阱效应.结果表明:开始时,增感产物起电子陷阱作用,至45min时,浅电子陷阱作用最佳.如增感时间进一步增加,硫增感产物将变为深电子陷阱.本文还讨论了浅电子陷阱中浅俘获光电子衰减时间与阱深的依存关系. 相似文献
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采用纳米硫化铅作为增感剂对边长为0.8μm的溴化银立方体颗粒进行了化学增感.利用微弱信号的微波吸收相敏检测技术,在超短脉冲激光作用下,获得了立方体溴化银乳剂中自由光电子和浅束缚光电子随增感时间变化的衰减曲线。通过测量溴化银光作用过程的时间分辨谱,讨论了卤化银晶体中电子陷阱对光电子运动行为的影响,分析了电子陷阱效应同增感时间之间的关系以及两个一级衰减区间寿命值同增感时间的关系.通过未增感样品与增感样品的衰减曲线对比,得到了在此实验奈件下的最佳增感时间为60min. 相似文献
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本文利用微波吸收相敏检测技术 ,同时获得了立方体AgBrCl乳剂中 ,在增感温度增加的条件下 ,自由光电子和浅束缚光电子的时间衰减曲线 ,分析了不同的硫增感产物随增感温度增加所起的陷阱效应。结果表明 ,在立方体AgBrCl乳剂中 ,硫增感初始阶段的增感产物主要是作为浅电子陷阱存在 ;随着增感温度增加至5 5℃时 ,增感产物浅电子陷阱效果最佳 ;如增感温度进一步增加 ,硫增感中心又变为深电子陷阱。文中还讨论了浅电子陷阱中浅束缚光电子衰减时间与阱深的依存关系。 相似文献
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溴碘化银核壳乳剂中电子的捕获和复合 总被引:2,自引:0,他引:2
本文应用双注仪制备了在核表面进行不同程度还原增感和一系列溴碘化银核壳乳剂,在没条件下测定了核表面形成的不同还原增感中心对乳剂微晶光电子衰减动力学及发光光谱的影响。结果表明:在一定增感温度和时间条件下,当Na2SO3用量低于5.4mg/molAg时光电子衰减动力学为二级反应,而当Na2SO3用量超过27mg/molAg时,增感中心一部分作为穴陷阱,另一部分作为电子陷阱,光电子衰减速率决定了电子的捕获 相似文献
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卤化银微晶体的光电子行为 总被引:2,自引:0,他引:2
卤化银乳剂微晶体的光电子行为是影响照相感光度的重要因素,本文就光电子研究方法、光电子衰减、电子陷阱、本征与外来带电中心对光电子衰减与寿命的影响以及光电子行为与其它物理性质的关系等方面加以综述. 相似文献
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The numbers of gold particles in a gold ruby glass were calculated as a function of irradiation time, nucleation and irradiation temperature, and cerium concentration. Photonucleation in Ce-containing glasses and nucleation by X rays in glasses without cerium were similar, suggesting that cerium was not directly involved in nucleating the gold particles. The results were consistent with nucleation by trapped photoelectrons. Temperature of irradiation and cerium concentration influenced production and recombination of the trapped electrons. A decreased number of nuclei as the nucleation temperature increased probably resulted from recombination of the trapped electrons. 相似文献
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曝光强度对卤化银微晶中载流子行为及其陷阱效应的影响 总被引:3,自引:0,他引:3
针对卤化银感光材料潜影形成过程中光作用动力学问题,分析了曝光强度对光生载流子行为和电子陷阱效应的影响,认为伴随着曝光强度的增加,影响光电子衰减的因素由电子陷阱起主要作用演化到电子陷阱和复合中心共同起作用进而演化到复合中心起主要作用. 相似文献
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Michael Filatov Seunghoon Lee Hiroya Nakata Cheol-Ho Choi 《International journal of molecular sciences》2021,22(8)
The non-adiabatic dynamics of furan excited in the ππ* state (S2 in the Franck–Condon geometry) was studied using non-adiabatic molecular dynamics simulations in connection with an ensemble density functional method. The time-resolved photoelectron spectra were theoretically simulated in a wide range of electron binding energies that covered the valence as well as the core electrons. The dynamics of the decay (rise) of the photoelectron signal were compared with the excited-state population dynamics. It was observed that the photoelectron signal decay parameters at certain electron binding energies displayed a good correlation with the events occurring during the excited-state dynamics. Thus, the time profile of the photoelectron intensity of the K-shell electrons of oxygen (decay constant of 34 ± 3 fs) showed a reasonable correlation with the time of passage through conical intersections with the ground state (47 ± 2 fs). The ground-state recovery constant of the photoelectron signal (121 ± 30 fs) was in good agreement with the theoretically obtained excited-state lifetime (93 ± 9 fs), as well as with the experimentally estimated recovery time constant (ca. 110 fs). Hence, it is proposed to complement the traditional TRPES observations with the trXPS (or trNEXAFS) measurements to obtain more reliable estimates of the most mechanistically important events during the excited-state dynamics. 相似文献
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Positrons which annihilate with electrons in solids usually give rise to two gamma rays, each with an energy close to 0.511 MeV, which are emitted in almost exactly opposite directions. The spread of the energies about the nominal value, which amounts to a few keV, is a Doppler effect reflecting the velocities along the direction of gamma emission of the electrons with which the positrons happen to annihilate. Thus the shape of the annihilation line gives a weighted measure of the electron momentum distrubution, emphasising the conduction electrons and the loosely bound localised electrons. The Positron Annihilation Techniques (PAT) allow this distribution to be determined non-destructively, and lend themselves to comparative measurements. If some of the positrons are trapped at negatively charged sites within a solid the annihilation radiation will reflect both the changed momentum distribution of the electrons seen at the trapping sites and the relative number of positrons which are trapped at the time of annihilation. To be effective the traps must have a mean spacing < 100 nm, but the sensitivity of PAT to atomic scale traps such as vacancies can nevertheless be very high. Finally, in materials containing few free electrons, information can be extracted from the formation of the positron analogue of the hydrogen atom, positronium. With standard positron sources probing depths in plastics can be a few millimetres. The PAT techniques have already proved their worth in investigations of electron momentum distributions in ordered solids, and in investigations of phase changes and of mechanical and fatigue damage in metals and alloys. Their out-of-the-way combination of characteristics makes them well worth consideration in other materials applications when conventional techniques run into difficulties. 相似文献
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T. Katsumata S. Toyomane R. Sakai S. Komuro T. Morikawa 《Journal of the American Ceramic Society》2006,89(3):932-936
SrAl2 O4 :Eu2+ phosphor crystals co-doped with auxiliary activators such as La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or Y have been grown by the floating zone (FZ) technique. Photoluminescence spectrum (PL), time-resolved PL, and thermally stimulated luminescence (TSL) are evaluated to clarify the long-duration phosphorescence mechanism of SrAl2 O4 , Eu, and Ln phosphors. TSL spectra were measured in the temperature range from RT to 600 K to evaluate the depth and densities of the traps generated by the doping of auxiliary activators that are responsible for the long-duration phosphorescence. The peak wavelength of PL does not vary with auxiliary activator elements, while decay curves vary greatly with the auxiliary activators. The trap depth and the densities of the trapped carriers estimated based on the hole trap model also vary with the auxiliary activator elements. The traps generated at around E =0.5 eV by the auxiliary activators, Nd, Dy, and Tm, with sufficient densities are effective for the long-duration phosphorescence. 相似文献
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A study of the dynamics of the electronic states of CdS semiconductor clusters grown in situ in reversed micelles via picosecond pump-probe technique reveals efficient transient bleaching of the excitonic absorption. This effect is attributable mainly to hole localization near the trapped electron, with no evidence of electron ejection (forming a solvated electron) detectable despite the apparent proximity of the cluster to the included water pool. Bleaching efficiency is cluster-size dependent, and recovery kinetics are governed by the nature of the particle surface. Similar decay behavior is observed in cluster fluorescence. Generally, the decay is characterized by two components, the faster attributed to recombination of a mobile, detrapped electron with a trapped hole, and the slower to an exchange interaction between trapped carriers. The observed strong multiexponentionality of the decay results from a distribution in trap energy levels, as well as from a distribution of distances between traps on the cluster surface. By varying preparation conditions, particles of different sizes with different surface defects can be grown in reversed micelles in a reproducible way so that their electronic properties can be controlled. 相似文献