Photography: enhancing sensitivity by silver-halide crystal doping
Photography: enhancing sensitivity by silver-halide crystal doping
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DOI：
10.1016/s0969-806x(03)00054-9
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发表时间：
2003-06-01
影响因子：
2.9
通讯作者：
Belloni, J
中科院分区：
文献类型：
--
作者：
Belloni, J
简要总结了银摄影过程的物理化学过程，即曝光、显影和定影。通过脉冲辐解研究了解了显影剂在曝光过程中在溴化银晶体中产生的团簇的自催化发展的机制，这是由这些团簇的临界核度控制的。由于随后一部分电子-空穴对在晶体内的快速复合，卤化银微晶中光诱导银团簇形成的有效量子产额Phi(Jeff)通常远低于光致电离理论极限Phi(Theor)=1个电子-空穴对。为了抑制这种复合和促进光电子还原银，在AgX晶体中掺入甲酸盐HCO(2)(-)作为特定的空穴清除剂。首先，掺杂剂清除了光生空穴，从而增强了电子从对复合中逃逸。第二，这样形成的CO(2)(.-)自由基将一个电子转移到另一个银阳离子，因此Phi(Jeff)极限可以是每个光子2AG(0)。这种光致双电子转移机制与吸收的光量子成正比，在完全抑制电子-空穴复合的情况下，在提高无线电或照相灵敏度方面产生了非凡的效率。(C)2003爱思唯尔科学有限公司。保留所有权利。
The physical chemistry of the silver photography processes, exposure, development and fixing, is briefly summarized. The mechanism of the autocatalytic development by the developer of the clusters produced in silver bromide crystals during the exposure which is controlled by the critical nuclearity of these clusters was understood from pulse radiolysis studies. The effective quantum yield Phi(eff) of photoinduced silver cluster formation in silver halide microcrystals is usually much lower than the photoionization theoretical limit Phi(theor) = 1 electron-hole pair per photon absorbed, owing to a subsequent very fast intra-crystal recombination of a part of the electron-hole pairs. In order to inhibit this recombination and favor the silver reduction by photo-electrons, the AgX crystals were doped with the formate HCO(2)(-) as a specific hole scavenger. First, the dopant scavenges the photoinduced hole, thus enhancing the electron escape from the pair recombination. Second, the CO(2)(.-) radical so formed transfers an electron to another silver cation, so that the Phi(eff) limit may be of 2Ag(0) per photon. This Photoinduced Bielectronic Transfer mechanism is strictly proportional to the light quanta absorbed and induces an exceptional efficiency for enhancing the radio- or photographic sensitivity insofar as it totally suppresses the electron-hole recombination. (C) 2003 Elsevier Science Ltd. All rights reserved.