反相微乳液法制备纳米Ag2S增感剂的化学增感研究

本文用反相微乳液法制备了纳米Ag₂S,并用作卤化银乳剂的硫增感剂,研究了其增感效果、增感规律及可能的增感机理.反相微乳液由异辛烷、表面活性剂AOT钠盐和水形成;制得的Ag₂S粒径3—5 nm;用制得颗粒增感卤化银乳剂,获得的感光性能优越于用Na₂S₂O₃水溶液增感;增感规律的研究表明,随着乳剂中纳米Ag₂S浓度的增加,模型乳剂感光度迅速提高、灰雾变化不大,并在100—200μmol/molAg左右获得最佳感光性能,进一步增加浓度则感光度呈下降趋势、灰雾升高;获得最佳感光性能所需的化学增感时间很短,约40分钟,之后感光度不再增加、灰雾上升;用漫反射光谱(DRS)作探针,跟踪记录增感时卤化银微晶表面上纳米Ag₂S增感剂颗粒的演变,为新型纳米增感剂的优异增感特性提供了机理性解释.

Ag2S Nano-Particles Prepared in Reverse Micelles Used for Sulfur Sensitization

In this paper 3—5 nm Ag₂S particles were prepared in the reverse micellar system and used as novel sensitizer in AgCl cubic and {100} tabular microcrystal emulsions.The novel sensitizer shows an effective sensitizing ability for AgX emulsion,and it is superior to the traditional Na₂S₂O₃ sensitizer because by using it comparatively high sensitivity can be obtained with lower fog density.To illustrate the evolution mechanism of the sensitizer clusters and explain their excellent sensitizing properties,diffuse reflectance spectroscopy(DRS) was used as a probe on the AgX microcrystal surface.