| 摘要 |
The grain/sensitivity ratio of a photographic silver halide material may be improved by adding a compound of the formula I to one of its layers. The material moreover exhibits a low increase in fog on storage. <IMAGE> (I) in which: Y1, Y2, Y3 each mean one of the following residues <IMAGE> ryl; two residues (R1 to R34) located on the same N atom may complete a 5-, 6- or greater-membered ring containing at least one N atom and optionally further heteroatoms; two residues (R1 to R34) located on adjacent N atoms may complete a ring involving both N atoms and at least one P atom; X- means an anion required to balance the charge, for example Cl-, Br- or tosylate (TosO-).
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