Some Observations on the Distribution of Latent Image in Core-Shell Emulsions

Presented in part at the International Congress of Photographic Science. Cambridge. England. 6-10 September 1982.

Abstract

Average latent image distribution profiles within a monodisperse core-shell emulsion have been measured through a three-stage technique in which dissolution in dilute thiosulphate solution is followed by washing and surface development. The validity of this technique, as a simpler alternative to differential development, was demonstrated by both electron-microscopic and sensitometric studies.

The technique was applied to three emulsions with a cubic core and octahedral shell that differed only in the degree of internal and surface sensitization. Flash exposure led to some surface image and a broad distribution of internal image, whereas long exposure gave no surface image but a broader distribution of internal image than that given by flash exposure. When surface digestion was increased and/or internal digestion reduced, a reversal of internal image was seen on flash exposure but not on long exposure.

These results are compared with other published data and a pattern of contrasting properties of internal and surface image-in which internal image is prone to reversal on flash exposure and surface image to solarization On long exposure -is noted. These differences are tentatively rationalized in terms of the phase-formation approach to latent image theory. Suggestions for a more systematic study of these phenomena are made.

Notes

Presented in part at the International Congress of Photographic Science. Cambridge. England. 6-10 September 1982.