Electronic Resource
Springer
The European physical journal
138 (1954), S. 381-393
ISSN:
1434-601X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Summary The role of crystal imperfections in the formation of the latent image in large crystals of silver bromide has now been established by experimental work. The internal latent image is formed by the separation of silver along dislocation lines associated with strained regions of the crystal and with the boundaries of the polyhedral substructure. Chemical sensitizing agents are adsorbed and react preferentially at the surfaces of regions of strain and imperfection in the crystals. Non-reacting sensitizing molecules are also adsorbed in the same regions because of the higher density of kink sites associated with them. This means that the chemical sensitizers are concentrated at the surfaces of strained and imperfect parts of the crystal where positive holes and electrons liberated during exposure are most likely to be trapped. It is postulated that the trapping of the holes occurs before that of the electrons and leaves the surface with a positive charge due to an excess of silver ions. The bromine atoms formed by the trapping of the holes by bromide ions occupying kink sites combine with atoms or molecules of sensitizers. The silver ions ultimately attach themselves to nuclei consisting of one or two metallic atoms and these positively charged aggregates then combine with the electrons. In this way larger aggregates are formed which may become positively charged in equilibrium with the silver ions of the crystal and act as development centres. With some molecular sensitizers, it is possible that a surface latent image is produced by the internal rearrangement of the molecule without the actual liberation of electrons.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01340684
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