Scanning Electron Microscopy and Atomic Force Microscopy of Fibrous Gelatin Observed between AgBr Microcrystals

Abstract

Gelatin has been the only circumstance for silver halides to grow of photographic use. However structural analyses of gelatin adsorption on silver halide microcrystals have rarely been made with microscopic methods. The present study shows the adsorption of gelatin on AgBr microcrystals with scanning electron or atomic force micrographs taken during the removal process of gelatin in photographic emulsions. Gelatin thin layers remained covering AgBr particles after most of the gelatin matrix was washed out in large quantities of warm water with strong agitation. The thin gelatin layers were again dissolved away and narrow strands of gelatin remained only where AgBr particles were packed close. The diameters of gelatin strands decreased gradually from the end where the strands adsorb on the surface of AgBr to reach the thinnest at the center. The smallest diameter observed in this study was about 20 nm, which must be a strand of many collagen helices. Two different methods to remove gelatin (conventional enzyme decomposition followed by centrifugal separation or the present warm water dilution with agitation and decantation) were compared and the warm water provided better exposed surfaces of AgBr with little gelatin residue.