1 Spectral sensitization of AgHal grains by dyes was discovered by Vogel in 1873 [1]. This phenomenon has been studied rather well and is widely applied in conventional photographic materials, providing their photosensitivity over the entire visible range and the near IR region of the spectrum [2][3][4]. A necessary condition for spectral sensitization is the adsorption of a sensitizing dye onto the grain surface. Cyanine dyes in the form of adsorbed J aggregates are known to be the most effective sensitizers for AgHal grains.Interplay between the nature and structure of the AgHal-grain surface and the absorption spectra of adsorbed sensitizer dyes was studied by many authors [5][6][7]. An analysis of published data leads to the conclusion that this factor can have a significant effect on the absorption spectra of an adsorbed dye.The addition of an ethanolic dye solution to an AgBr emulsion produces a significant bathochromic shift of the monomer absorption band, which is believed to be due to the formation of J aggregates [3]. A cyanine dye adsorbed from an aqueous methanolic solution (20% MeOH) onto the surface of AgBr and AgCl grains with different faceting was shown to have different absorption maximums of the aggregate depending on the nature of the substrate [7]. Meso -ethylsubstituted carbocyanines are adsorbed onto the {111} AgBr surface in the form of J aggregates with the packing angles in the structures of 30° and 19° .Cationic and anionic dyes are readily adsorbed on cubic and octahedral AgHal grains. However, the same dye has different abilities to form J aggregates on the {100} and {111} faces. Furthermore, the absorption spectra of dyes of the cationic and anionic types adsorbed onto the grains of the same form are different [8]. 1 e-mail: brichkin@icp.ac.ru Meso -ethyl-and meso -phenylsubstituted carbocyanines are adsorbed in the all-trans form on the {111} faces of AgBr but in the all-cis form on the {100} faces [7]. Boyer and Cappelaere [6], and Markocki [9] believe that J states appear more readily on grains that have the cubic form with the {100} faces, with the energy of adsorption of the dyes on these faces being higher than on the {111} faces [10].In contrast to this, Eggers et al. [11] and Philippaerts et al. [12] claim that J aggregation is favored by the crystallographic structure and electrostatic properties of {111} faces, and only those dyes whose aggregation is significantly affected by the aqueous medium form J aggregates on the surface of cubic grains [12]. Breslav et al. [8] concluded that cyanine dyes form more diverse structures in an emulsion with octahedral grains, whereas J aggregates in an emulsion with cubic grains have a more uniform structure and are stronger adsorbed on the silver halide surface.The state of an adsorbed dye substantially depends on its concentration. At low surface concentrations of cyanine dyes on AgHal and other adsorbents, their absorption spectra correspond to the molecular form of the dye ( å ‡ ) with a bathochromic shift (~30 nm on AgHal) whose val...