The combination of spectroscopic information concerning the light absorption, spectral sensitivity, and photobleaching involving the reduction sensitization centers allowed reasonable positioning of their electronic energy levels relative to the band edges of silver halides. A well-defined absorption band centered at 455 nm was observed both for the reduction sensitization centers produced by dimethylamine borane (DMAB) and for the hydrogen hypersensitization centers by using a diffuse transmittance spectroscopy method. We conclude that the common type of reduction sensitization centers, which must be predominantly hole trapping, have their HOMO (highest occupied molecular orbital) levels ∼1.9 eV below the conduction band edge. Additional centers produced at the high level of DMAB sensitization have a higher HOMO level ∼1.6 eV below the conduction band edge, which is identical with that previously ascribed to the subimage center. The dielectric polarization of the surrounding medium critically affects these energy levels. Possible limitations of the spectroscopic information as well as its advantages are also discussed.
Mitsuo Kawasaki, Yoshiaki Oku, "Energy-level Assessment for Small Silver Clusters in AgBr Emulsion from Combined Experimental Data of Light Absorption, Spectral Sensitivity and Photobleaching" in Journal of Imaging Science and Technology, 1998, pp 409 - 415, https://doi.org/10.2352/J.ImagingSci.Technol.1998.42.5.art00008