The interaction between photographic gelatins and chemical sensitizers

The interaction between two kinds of photographic gelatin and chemical sens itizers was studied by X-ray Photoelectron Spectroscopy. After the gelatin samples were immersed into the chloroauric acid solution for 5 min, methion ine and methionine sulfoxide in gelatins were oxidized to methionine sulfon e, reducing most parts of Au3+ to Au which was coordinated by gelatin macro molecule. According to the ratio of Au3+ to Au in gelatins, it is shown tha t the reducing power of Rousselot gelatin is stronger than that of Baotou g elatin. When sodium thiosulfate was added to gelatins, methionine sulfoxide was reduced to methionine. Sodium thiosulfate, which is a reductant strong er than both methionine and methionine sulfone, could coexist steadily with methionine and methionine sulfone in the gelatin. Two kinds of photographi c gelatins added with sodium thiosulfate could reduce Au3+ to colloid gold. In this redox reaction, the main reductant is sodium thiosulfate, but not methionine in the gelatin. The addition of sodium thiosulfate enhanced the reducing power of the photographic gelatin.