Abstract: A series of emulsions with the iodide content of 30mol% in core and with the core/shell ratio of 1:1, 1:2, 1:3, and 1:4 was prepared by combined core-precipitation and shell-formation with the double-jet technique.The micro-component analysis in the individual single crystal was conducted with the STEM-EDS method.It was shown that in the emulsion micro-crystal really exists the composite structure of iodide-rich core and iodide-poor shell, and what is more, the surface iodide concentration decreased with increasing core-shell ratio.The light absorption was measured by UV-240 spectrophotometer.The ionic and photo-electron conductivities were determined by dielectric loss measurement and microwave photo-conductivity method respectively.It was shown that the light absorption values for the 4 different emulsion microcrystals were found to be no essential difference as a result of the combined influence of two different contradictory factors the decrease of total iodide content and the increase of grain size of the microcrystals.The photo-conductivity signal intensity enhances with increasing core/shell ratio, the photoelectron lifetime becomes the longest for emulsion No.3, the core-shell ratio of which is 1:3.The corelations between the above-mentioned photophysical and electric properties, and the sensitometric behavour were presented and discussed.

Key words: photographic chemistry, core-shell emulsion, ionic conductivity, photoconductivity