Sensitization Of Silver Halide Grains Emulsion Doped With Carboxylic Salt

In order to discuss sensitization of carboxylic salt (including formate sodium, oxalate potassium) to silver bromide emulsion, prescription design, preparation, and measurements of photographic properties of silver bromide emulsion doped with carboxylic salt were studied. furthermore, sensitization mechanisms of carboxylic base, especially formate and oxalate base, to silver bromide emulsion were discussed. In addition, the effect of formate and oxalate salt doped on the photographic properties of AgBr emulsion and water-base photothermographic materials was respectively studied. The main results were summarized as follows:1. Preparation and measurements of photographic properties of cubic AgBr emulsions doped with formateThe results from measurements of photographic properties of these emulsions showed: the sensitivities of emulsions in which formate were doped at subsurface, relative to that of the undoped emulsion as the controlled one, were remarkably increased; the closer to the surface of grains the formate doped in AgBr grains was, the greater the sensitivities of the doped emulsions were, especially sensitized by dye sensitization; a significant cooperative sensitization of the internal doped formate with the surface sulfur-plus-gold and dye sensitizations was observed; fog densities all emulsions doped by formate, including those sensitized by S+Au and the dye, were kept in a reasonably low level; the maximal sensitivity gain (Smax/S0) of undye-sensitized emulsions was greater than those of dye-sensitized ones.2. Preparation and measurements of photographic properties of cubo-octahedral AgBr emulsions doped with formateBy use of the double-jet apparatus controlled by a microcomputer, cubo-octahedral AgBr grain emulsions in which formate ions were doped at subsurface of AgBr microcrystals, were prepared. By calculation, the ratio of facet (100) to facet (111) of this kind of grains is about 2:3. The sensitometric results from these emulsions showed: that the sensitivities (Sd) of formate-doped emulsions, relative to those (S0) of the corresponding undoped ones as the controlled, regardless of whether it is primitive, or sensitized chemically and spectrally, were remarkably increased without a significant increase in fog density (Sd/S0≈2).3. Preparation and measurements of photographic properties of cubic AgBrI emulsions doped with formateBy use of the double-jet apparatus controlled by a microcomputer, cubic AgBrI grain emulsions in which certain amount of formate ions were doped at subsurface, and different amount of I- doped in interior, were prepared. The sensitometric results from these emulsions showed: that sensitivity of formate-undoped and -doped AgBrI grain emulsions, regardless of whether it is primitive, or sensitized chemically, increase with amount of I- doped in AgBrI emulsion; the sensitivities of formate-doped AgBrI emulsions, relative to those of the corresponding undoped ones as the controlled, regardless of whether it is primitive, or sensitized chemically and spectrally, were remarkably increased, while fog level of those were kept lower;4. Preparation and measurements of photographic properties of cubic AgBr emulsions doped with oxalateIn the emulsifying process of AgBr microcrystals in the double-jet apparatus controlled by a microcomputer, a certain amount of oxalate salt was injected at specific time and pAg into a reactor to prepare cubic AgBr grain emulsions in which oxalate ions were doped at subsurface of AgBr microcrystals. The observation results from the whole experiments and sensitometric results from these emulsions showed: the sensitivities (Sd) of oxalate-doped emulsions, relative to those (S0) of the corresponding undoped ones as the controlled, regardless of whether it is primitive, or sensitized chemically and spectrally, were remarkably increased(Sd/S0≥1.5), while fog level of those were kept low; Those sensitization gains of oxalate-doped emulsions were nearly same as one of formate-doped emulsions; that the preparation of cubic AgBr emulsions doped with oxalate was simpler than those of cubic ones doped with formate, and the formers'shape was sharper than the latters'.5. The effect of formate and oxalate doped on the photographic properties of AgBr emulsion and water-base photothermographic materials.The results showed that the relative sensitivities of PTG materials were remarkably increased when the doped AgBr emulsions were used as silver elements in PTG materials, whereas the fog did not change. In addition, dope sensitization also cooperated with sulfur, gold, sulfur plus gold sensitization in PTG materials, which further improved the relative sensitivity of PTG materials. Doped AgBr emulsion had an optimal amount with AgBr to silver stearate of 1:4 in PTG material.