AgBr核壳乳剂的颗粒内部还原增感与表面化学增感的协同增感效应

Cooperative Sensitization of AgBr Core-Shell Emulsions by Internal Reduction and Surface Chemical Sensitization

采用对核颗粒进行还原掺杂和将其包壳的方法制备了一系列不同DMAB用量、内部有还原敏化中心(Ag2)的AgBr核壳乳剂.这些乳剂表现出明显的增感效应.当这些乳剂分别进行表面硫、金和硫加金增感后,一方面表现出明显的协同增感效应;另一方面又随DMAB用量的提高,灰雾明显增长,特别是在金增感和硫加金增感的情况下.此外实验结果还证明,提高核乳剂的包壳速率可以在一定程度上减少核壳乳剂的灰雾.

A series of cubic AgBr core-shell emulsions were prepared from the core emulsions reduced by DMAB and shelled by AgBr.These core-shell emulsions doped with Ag_2 in the interior of grains exhibited a significant increase in sensitivity.After these emulsions were sensitized respectively by sulfur,gold or sulfur-plus-gold,the relative sensitivities of the emulsions were much higher than that of the controlled ones without Ag_2 in the interior of grains,i.e.=0.The results showed that a cooperative sensitization of the AgBr core-shell emulsions by internal reduction and surface chemical sensitization.On the other hand,the fog densities of these chemically sensitized emulsions rose rapidly with the amount of DMAB added in preparation of core emulsions,particularly in the cases of sulfur-plus-gold or gold sensitization.It was considered to be related to Ag_2 on the surface of grains,which were expelled from the cores in shelling process.In addition,an increase in the shelling rate was more favorable to depress the fog.