Abstract: A series of truncated cubic emulsion microcrystals with different shell thickness was prepared by double-jet method with automatic control of pAg. The grain size and its distribution were measured with combined optical microscopy and image processing technique. Their relative light absorption was determined by UV spectrophotometry. Their ionic and photo-electron conductivity were determined with the dielectric loss and microwave photoconductivity methods respectively as a function of shell thickness. It was shown that the relative absorption intensified with the shell thickness increase, but on the contracy, the ionic conductivity droped with Ar increase. The photo-electron conductivity first intensified with Ar increase, passed through a maximum (△r = 1:2.2), and then droped fastly (△r>1:3.5). The corelations between the relative light absorption, electric properties and the sensitometric properties had been presented (Fig.1) and elucidated, the optimum shell thickness for higher sensitivity is shown to be in accordance with the thickness of the surface space charge layer (so called Debye length) of the emulsion microcrystals.

Key words: photographic chemistry, core-shell emulsion, preparation, property