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Volume: 40 | Article ID: art00015
Quantitative Study of Photohole-Induced Bleaching of Latent Image Centers in AgBr Emulsions
  DOI :  10.2352/J.ImagingSci.Technol.1996.40.6.art00015  Published OnlineNovember 1996

The photohole-induced bleaching of latent image and subimage centers in AgBr emulsions in the intrinsic absorption region has been studied quantitatively by using phenosafranine dye as an effective photoelectron scavenger. The quantum bleaching efficiencies of the minimum latent image centers in our standard development condition were thus estimated to be typically ∼0.8 × 10−3 (1 × 10−3), ∼3 × 10−3 (3 × 10−3), and ∼5 × 10−3 (4 × 10−3), respectively, for primitive, S-sensitized, and S + Au-sensitized emulsions consisting of 0.4 − 0.53-μm cubic (0.55-μm octahedral) grains. A much higher quantum bleaching efficiency of ∼1 × 10−2 was measured for what we identified with a two-atom subimage center. The hole-induced bleaching efficiency measured in this way correlates well but inversely with the energy gap between the highest occupied level of the center to be bleached and the valence band edge that can be derived from the corresponding photoionization threshold independently measured elsewhere. The observed energy-gap dependence suggests that the quantum bleaching efficiency is controlled kinetically by hole capture cross section that increases with decreasing hole-trapping depth, as expected for nonradiative, multiphonon processes. The present study also provides additional evidence to support that S + Au-sensitized grains allow latent image centers both with and without built-in gold atoms to form under high-intensity exposure.

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Yoshiaki Oku, Mitsuo Kawasaki, "Quantitative Study of Photohole-Induced Bleaching of Latent Image Centers in AgBr Emulsionsin Journal of Imaging Science and Technology,  1996,  pp 582 - 590,

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Copyright © Society for Imaging Science and Technology 1996
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