Journal of The Society of Photographic Science and Technology of Japan

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A detailed review is made for the mechanism of reduction sensitization. Experimental results with regard to it are summarized, that is, it increases both surface and internal sensitivity, does not decrease photoconductivity, and depresses low intensity reciprocity failure, action of it does not compete sulfur sensitization or phenosafranine, and its specks are destroyed by exposure. They seem to suggest that reduction sensitization specks act as hole traps. It is also shown that opposite phenomena exist especially at high level of sensitization, that is, decrease of internal sensitivity and photoconductivity. Presence of two kinds of reduction sensitization specks, acting as electron traps and hole traps, is considered. Discussions about a difference between them are introduces. One hypothesis for the difference is the size and the other is the electric charge. At the former, small specks are hole traps and large specks are electron traps. At the latter, positively charged specks are electron traps and negatively charged or neutral specks are hole traps. It is suggested that at small specks difference of charge determines those properties but at large specks this difference does not become important and they mainly act as electron traps. It is also emphasized that hole trapping and halogen accepting are different action and the destruction of reduction sensitization specks by exposure is a phenomenon of solarization.

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In hydrazine-nucleated infectious development, one of the practical problems has been black spots (BS). In this paper, we describe BS morphologically, and explain two different means for restraining BS. One of them is an anion charge barrier, formed by adsorption of some kind of dyes on AgX. The other is control means of timing between fogging development and following infections development by organic acid polymer. It is also suggested that the active species in the infectious development has anion charge character and some side reactions of oxidized developer and active species play significant role.

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Dissociation constants and heat of dissociation of dimeric associates of an anionic oxacarbocyanine dye, potassium 3, 3'-bis [3-sulfopropyl]-5, 5'-diphenyl-9-ethyloxacarbocyanine (DYE), in aqueous ethanol solutions have been determined from the monomer band absorbance of the dye measured at different temperatures and dye concentrations at which the monomer is the major solute species and disturbance of monomer absorbance measurements by associated species is fairly small. In 10% ethanol, the dissociation constant was 2×10^-5 mol/dm³ (20°C)-7×10^-5 mol/dm³ (40°C), and the heat of dissociation was about 10 kcal/mol (42kJ/mol), suggesting a higher dimer stability of DYE than that of typical cationic thiacarbocyanines.

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In order to investigate the process of ultrasonic degradation of gelatin, three types of gelatin were irradiated with ultrasound. Then the contents of each fraction of the samples were determined with HPLC. As a result, it was found that the kinetics of ultrasonic degradation of fraction H (higher component) is first order. And the degradation rate constants (k) varied with type and concentration of gelatin.

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