Radiation-sensitive emulsion, silver halide photographic film material and radiographic intensifying screen-film combination

Chemically and spectrally-sensitized silver halide photographic emulsion having (100) cubic silver bromoiodide grains or crystals with an average edge length of from 0.2 up to 1.5 μm and a high degree of monodispersity in that a variation coefficient on said average edge length is less than 0.20, wherein said grains have been spectrally sensitized in the wavelength range from 540 nm to 555 nm with at least three spectrally sensitizing dyes:

• a main spectrally sensitizing dye present in an amount of at least 85 mole %,
• a second spectrally sensitizing dye present in an amount of less than 10 mole %, and
• a third spectrally sensitizing dye present in an amount of at most 5 mole %,
• said amount being expressed in mole % based on total molar amounts of all spectrally sensitizing dyes added;
• characterized in that
• at least said main spectrally sensitizing dye is a methine dye comprising first and second nuclei joined by a substituted or unsubstituted trimethine linkage, wherein at least nuclei are both benzoxazole nuclei, said nuclei being each substituted by one halogen atom or by a methyl group in the 5- and 5′- or 6- and 6′-position respectively;
• the N-atom of which has a substituted or unsubstituted alkyl chain having from 1 to 4 carbon atoms and a water-soluble group;
• at least said third spectrally sensitizing dye is a methine dye comprising first and second nuclei joined by a substituted or unsubstituted trimethine linkage, wherein both nuclei are benzimidazole nuclei, said nuclei substituted by one or more halogen atom(s) in the 5-, 5′-,6- and/or 6′-position, or by a methyl group;
• the N-atoms of which having a substituted or unsubstituted alkyl chain having from 1 to 4 carbon atoms and a water-soluble group on at least on one N-atom;
• and in that
• the said second spectrally sensitizing dye is a trimethine dye comprising a benzoxazole nucleus and a benzimidazole nucleus, and wherein, apart from the presence on at least one N-atom of a water-soluble group, other substitutions are providing an asymmetrical structure.