On the Photographic Reciprocity Law Failure and Related Effects. I. The Low Intensity Failure

(1) The order principle (o.p.) states: ``The grains of an emulsion become developable in the course of an exposure in a given sequence independent of the exposure and development variables.'' This hypothesis appears to have a wide range of applicability. It forms an ideally simple link for correlating experimental isodense exposures and theoretical single grain response predictions. Moreover, in many cases where the o.p. is not strictly applicable, corrections can be derived (Section 12) which again make quantitative comparison of theory and experimental data possible.(2) Extending ideas of Gurney, Mott, and Webb, a quantitative theory of the low intensity reciprocity law failure (l.i.f.) is developed, by analyzing the statistics of light absorption and the survival function of the electrons. Confrontation of various theoretical possibilities with experimental data selects the following basic assumptions: (a) A monoatomic Ag speck of sub‐latent image is unstable against thermal agitation, but a diatomic speck is stable for most practical purposes; finally a triatomic speck is completely stable. (b) The energy required to set free an electron from a monoatomic speck (electron trap depth) is not the same for all traps. There must be a quasi‐continuous distribution of depths (e.g. as given by formula (10)).With these assumptions the theory describes satisfactorily the principal features in the shape of experimental l.i.f. curves. It is found that the l.i.f. slope varies systematically with grain size and the theory checks qualitatively with this result. The experimental temperature dependence of l.i.f. curves agrees satisfactorily with the theory.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71185/2/JCPSA6-17-11-1132-1.pd