M. Sydow et al., PHOTOGRAPHICAL AND UV-VIS SPECTROSCOPICAL INVESTIGATIONS OF LIGAND PROTECTED SILVER CLUSTERS IN ULTRA-FINE GRAINED AGBR AND AGBR I EMULSIONLAYERS/, Journal of information recording, 23(4), 1996, pp. 387-399
Various emulsion layers with different photographic sensitivities were
produced from ultra fine grained silver-halide-gelatin-emulsions chem
ically sensitized in four different ways (I.: without chemical sensiti
zers, II: sulfur sensitized, III: gold sensitized, IV: sulfur+gold sen
sitized). The different sensitivities were compared with the different
W-VIS-spectra of photo induced silver clusters formed by exposure of
the Various emulsion layers to flash light. The UV-VIS-spectra display
ed absorption bands at about 340nm (oligomeric silver clusters with 5
silver atoms), 390 nm (plasmon polaritons of 4 nm silver clusters surr
ounded by Ag+ ions), 470 nm, 530 nm and 630 nm. The absorption range b
etween 420nm and 700 nm may be attributed to silver clusters with diam
eters about 4 nm, too. When these clusters are embedded within the int
erface ''gelatin/silver halide'', or within silver bromide, absorption
maxima at 470 nm, or 530 to 540 nm, respectively may occur. The 630 n
m band may occur, when the cluster concentration within the interface
''gelatin/silver halide'' becomes so large that the clusters are allow
ed to approach each other to distances less than one particle diameter
. Sensitivity gains, above all, run parallel with remarkable red shift
ings of the 630 nm absorption maximum. The gold sensitization has rema
rkably influenced the 630 nm band.