METHOD OF SPECTRAL SENSIBILIZATION OF BROMOIODOSILVER PHOTOGRAPHIC EMULSION Russian patent published in 1995 - IPC

FIELD: photographic materials. SUBSTANCE: sensibilization process is carried out by successive addition to the melt of ammonialess polydispersed bromoiodosilver emulsion [content of AgJ is 5-13.5 mol.%; pH is 6.3; pBr is 2.9; crystal diameter is 1.3 mcm]: a) the first sensibilizing dye; b) after pause the second sensibilizing dye and the same activating agent were added. Before I-dye compound were added at concentration 1-2 g/kg emulsion. The following compounds were used:-compound of the formula where a) Y -S; A - A = CH₃;; B = B₁=H; R= [CH₂]₃SO₃;; K = C₅H₃N^⊕H;; b) Y - Y = > NC₂H₅; A=B= H; B₁= CN;-CN; R = C₂H₅; K=H; Y=O; A=A = C₂H₅; B=B = OCH₃; B₁= Cl;=Cl; R- R = C₂H₅;; K-H. Dyes were taken at concentration [120-150] x [120-150]·10^-6 M/M AgHal with equalmole ratio of sensibilizing agent at activating agent. Under these conditions photosensitivity of photomaterial is increased at assigned contrast coefficient and significantly decreased fog density and increased resolution capability. EFFECT: increased photosensitivity of photoemulsion. 2 tbl