THE INFLUENCE OF STRUCTURES OF SENSITIZING DYES ON THEIR ADSORPTION AND SIZE DISTRIBUTION OF J-AGGREGATES ON AGBR GRAIN BY ACFEM

The effects of different substituents on thiacarbocyanine and indocarb ocyanine dyes on their adsorption to AgBr microcrystals and on size di stributions of J-aggregates were investigated by analytical color fluo rescence electron microscopy (ACFEM). The results showed that the adso rbability of the indocarbocyanine iodide dye on cubic AgBr grains was greater than that on the T-grain AgBr. On the other hand, adsorbabilit y of the thiacarbocyanine triethyl ammonium salt on the T-grain AgBr w as greater than on the cubic AgBr. In addition, adsorbabilities of 5-s ubstituted thiacarbocyanine dyes either on T-grain or on cubic AgBr we re much greater than those of 5-unsubstituted thiacarbocyanine dyes. W e inferred that growth of J-aggregates on AgBr could be regarded as Os twald ripening, and that substitution of the indocarbocyanine with an N-ethyl substituent led to strong J-aggregation. The average size of J -aggregates of 5-substituted thiacarbocyanine dyes formed on cubic AgB r were larger than the average size of J-aggregates of the 5-unsubstit uted.