SPECTROSCOPIC STUDY OF A SPECTRALLY SENSITIZED TABULAR GRAIN AGBR EMULSION USING BOTH AFM AND PSTM TECHNIQUES

The scope of this study was to correlate the topographic information p rovided by atomic force microscopy (AFM) with optical properties of th e AgX tabular grain photographic emulsion samples collected with near- field optical microscopies. Images of spectrally sensitized AgBr tabul ar grains were performed, using both AFM and photon scanning tunneling microscopy (PSTM). PSTM images of spectrally sensitized AgBr microcry stals, recorded at various excitation wavelengths, showed an amplifica tion of the apparent thickness of the grains when excited in the absor ption range of the dye. This can be explained by the contribution of t he fluorescence of the sensitizing dye to the measured signal in the P STM. The increase of the PSTM response depended also on the dye covera ge and on the stack of microcrystals. The visible absorption and fluor escence spectra of the spectrally sensitized emulsion obtained at room temperature at a macroscopic scale were in good agreement with the PS TM observations.