Absorption spectra of AgHal emulsions Absorption spectra of ultra-fine-grained AgCl (a), AgBr (b) and AgI (c) photolayers (photoemulsions). Exposured layer. - презентация

1 Absorption spectra of AgHal emulsions Absorption spectra of ultra-fine-grained AgCl (a), AgBr (b) and AgI (c) photolayers (photoemulsions). Exposured layer (-.-), non-exposured layer (-..-), gelatine layer treated in NaNO 2 and irradiated by UV light (-…-).

2 Absorption spectra of AgHal emulsions Influence of crystal size Change of absorption spectra of the irradiated layer at variation of growth time of AgBr microcrystals (" physical ripening ") (t = 36 o C): 0 min (-.-), 90 min (-..-), 90 hours (-…-). Change of absorption spectra at fixation of exposured photolayer. Concentration of Na 2 S 2 O 3. 5H 2 O - 5 weight. %. An initial sample (-.-), 10 s (-..-), 1 min (-…-), 3 min (-….-) of treatment.

3 Absorption spectra of AgHal emulsions Influence of crystal size Processing fixed layer in a standard fixing solution: 3 min (-.-), 1 h (-..-), 4 h (-…-), 12 h (-….-). The dependence connecting a starting position of spectral absorption maxima (an X axis) with a maximum of the strip which have arisen after full dissolution AgBr of an initial irradiated layer (an Y axis).

4 Absorption spectra of AgHal emulsions Influence of crystal size Change of absorption spectra of exposured layer during processing in NH 3 solution: Initial sample (-.-), 5 s (-..-), 15 s (-…-), 60 s (-….-), 7 min (-…..-). Processing of experimental spectrum with the help of computer on maxima for primary (-.-), secondary (-..-) coloring centers and for "limiting" distribution of silver (-…-). Table: A – initial positions, B – after processing: Type of distribution of silver centers appropriated to absorption maxima Time of treatment, s Primary color centers ABAB ? 395 -?-? Secondary color centers ABAB ? 531 ? "limiting" distribution of silver ABAB ---- ? 481 ? ?" - position of maximum cannot be defined visually, "-" - maximum in a spectrum is absent

5 Absorption spectra of AgHal emulsions Influence of crystal size Change of a spectrum of absorption at long intensive photolysis. Time of exposure: 10 s (-.-), 20 s (-..-), 1 min (-…-), 2 min (-….-), 5 min (-…..-), 20 min (-……-), 50 min (-…….-), 90 min (-……..-). Change of absorption spectra depending on a number of sedimentation zone in centrifuginal tube. 1 st zone (-.-), 2 d zone (-..-), 3 d zone (-…-), 4 th zone (-….-), 5 th zone (-…..-), 6 th zone (-……-), 7 th zone (-…….-), 8 th zone (-……..-) – bottom of centrifuginal tube.

6 Photolysis of layers from soluble silver salts Absorption spectrums of CH 3 COOAg containing gelatin layers after photolysis. Concentration of salt: 1, g/cm 2 (a), 5, g/cm 2 (b), 2, g/cm 2 (c), 5, g/cm 2 (d). Original spectrums (-), spectrums of colloidal particles (-.-.-), molecular clusters (- - -), colloidal particles with size 3 nm (….). Table: A – initial maxima positions, B – after processing Type of distribution of silver centers appropriated to absorption maxima Concentration of CH 3 COOAg, g-eq/m 2 1, , , , Primary color centers ABAB Secondary color centers ABAB ? 384 ? 373 "limiting" distribution of silver ABAB ? ?" - position of maximum cannot be defined visually, "-" - maximum in a spectrum is absent

7 Absorption spectra of AgHal emulsions Influence of crystal size Dependence between position of spectral absorption maxima of the color centers and the sizes of AgBr microcrystals where they are formed.

8 Granulometric analysis of coloring centers 1. The experimental dependence connecting the sizes of silver colloidal particles (d Ag ) with position of their spectral absorption (λ Ag ), for medium with refraction coefficient n D 20 = 1,5 (gelatin, glass, Formvar etc.): d Ag (λ Ag ) exp.1,5 2. The theoretical dependences connecting the same parameters for particles of silver in gelatin (n D20 = 1,5) and in bromide of silver (n D 20 = 2,3) : d Ag (λ Ag ) theor.1,5 and d Ag (λ Ag ) theor.2,3. 3. For microcrystals of silver bromide, primary and secondary cororing centers of various sizes, the analysis of process of microcrystals dissolution in solutions of NH 3 (or Na 2 S 2 O 3 in such conditions that silver of colouring centres was kept in the best way) is carried out. As a result of experiment it was possible to receive dependence between spectral position of the maximum corresponding to colloidal and molecular coloring centers (the secondary and primary centers) - both λ Ag(2) and λ Ag(1), and a maximum of absorption formed "limiting" coloring centers λ Ag (λ Ag(1), λ Ag(2) ). 4. Electronmicroscopic and specrtophotometric investigations have shown interrelation between sizes of AgBr microcrystals and maxima of spectral absorption primary and secondary coloring centers. With the help of methods of carbon replics and ultra thin cuts the dependence d AgBr (λ Ag(1), λ Ag(2) ) is received. On the basis of the listed results in the given chapter calculation of the sizes and quantities of coloring centers is carried out.

9 Granulometric analysis of coloring centers Ag(2) - wave length of absorption maximum of colloidal particles (secondary coloring centers), nm, d Ag(2) - diameter of silver colloidal particles, nm, n Ag(2) - number of silver atoms in colloidal silver particles, Ag - wave length of absorption maximum of limiting silver distribution, nm, d Ag - diameter of colloidal particles of limiting distribution of silver, nm, n Ag - number of silver atoms in colloidal particles of limiting distribution of silver, Ag(1) - wave length of absorption maximum of molecular particles (primary coloring centers), nm, n Ag(1) - total number of silver atoms in molecular coloring centers, d AgBr - diameter of silver bromide crystal, nm, n AgBr - number of molecules in microcrystal of silver bromide, S - solubility of silver, at.Ag/molec.AgBr, h - specific solubility" of silver, - surface tension of silver on the border Ag-AgBr, mJ/m 2 n = ( d 3 )/(6v o ) n Ag(1) = n Ag - n Ag(2) S = n Ag(1) / n AgBr h = n Ag(1) / n Ag(2)

10 Granulometric analysis of coloring centers For massive silver (by n Ag(2) ) S oo = 2, at.Ag/molec.AgBr (or for molecules AgBr - 2, at.Ag) And for oligoatomic distribution of silver (by n Ag(2) 1) S 1 = 0,68 at.Ag/molec.AgBr (and for molecules AgBr - 6, at.Ag). Relationship S 1 /S oo gives the possiblility to define the degree of supersaturation of silver 0, , which can be achieve during photolysis process for ultra-fine- grained emulsions. Dependence h(n AgBr ) gives the possibility to define the degree of solubiluty of silver for massive AgBr crystals (n AgBr ) h oo = 0,2.

11 Granulometric analysis of coloring centers