Recent progress in the mechanism of latent image formation and roles of silver clusters in photographic sensitivity is reviewed with respect to classification of silver clusters: comparison between light and reduction clusters; preferential formation of reduction sensitization R centers to P centers; difference between latent sub-image centers and P centers; characterization of R and P centers by photoconductivity measurements; utility of R centers with two electron sensitization; and direct observation of latent image and fog centers.
Tadaaki Tani, "A Review of the Mechanism of Photographic Sensitivity and Roles of Silver Clusters" in Journal of Imaging Science and Technology, 2004, pp 278 - 284, https://doi.org/10.2352/J.ImagingSci.Technol.2004.48.3.art00014