Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/08—Sensitivity-increasing substances
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/09—Noble metals or mercury; Salts or compounds thereof; Sulfur, selenium or tellurium, or compounds thereof, e.g. for chemical sensitising
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/067—Additives for high contrast images, other than hydrazine compounds
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/07—Substances influencing grain growth during silver salt formation
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
  • G03C2001/03511—Bromide content
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
  • G03C2001/03517—Chloride content
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/035—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein characterised by the crystal form or composition, e.g. mixed grain
  • G03C2001/03535—Core-shell grains
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/06—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with non-macromolecular additives
  • G03C1/08—Sensitivity-increasing substances
  • G03C1/09—Noble metals or mercury; Salts or compounds thereof; Sulfur, selenium or tellurium, or compounds thereof, e.g. for chemical sensitising
  • G03C2001/094—Rhodium

Definitions

• the present invention relates to a photosensitive silver halide emulsion, a method for making such emulsion and a photosensitive material containing said emulsion. More specifically the present invention is related to a high sensitive silver halide photographic material with an increased image contrast.
• the ligands of the dopant are also included in the crystal structure and will modify the photographic properties as well.
• an increase of gradation by addition of dopants is also accompanied by a decrease of sensitivity further depending on the kind of metal ion, its valency, ligand structure and amount of metal-complex added during precipitation.
• This sensitivity decrease can advantageously be used to make less light-sensitive materials which can be handled under safelight conditions.
• these materials are e.g. used for roomlight operations, as in contact printing of halftone film materials where negative or positive copies are made from screened originals by dot per dot reproduction.
• the dopants which will be discussed here are characterised by building a deep electron trap in a silver halide crystal lattice.
• Such trap is called 'deep' if following two conditions are fulfilled: the LUMO of the incorporated molecular entity should be at least 0.5 eV below the conduction band of the silver halide crystal, and the trapping life-time at room temperature should be higher than 0.2 seconds (see R.S.Eachus, M.T.Olm in 'Cryst.Latt.Def.and Amorph.Mat.',1989(18)297-313).
• the LUMO is defined as the 'lowest unoccupied molecular orbital' of the related complex which can trap an electron from the conduction band (see D.F.Shriver, P.W.Atkins, C.H.Langford in "Inorganic Chemistry'-Oxford Univ.Press (1990), Oxford-Melbourne-Tokyo).
• the said iridium dopant is especially in favour of an improvement of the high intensity reciprocity failure and latent image stability.
• Increasing the contrast as much as possible needs a rather high amount of dopant homogeneously distributed over the crystal volume which is also required in order to keep maximum density and to prevent solarization.
• This has its consequences in using automatic processors where the increasing load of metal complexes by continuous processing asks for special attention in regeneration afterwards.
• the sensitometric problems as density-loss and solarisation can be solved by a method given by Gingello and Schmidt in EP-A 0 697 619 proposing a non-uniform incorporation of the same dopants. Therefore the metal complexes are built in mainly in the outer region of the crystals.
• the precipitation of a photosensitive silver halide emulsion is conducted in an aqueous dispersing medium including, at least during grain growth, a peptizer wherein silver ions and halide ions are brought together.
• Grain structure and properties can be selected by control of several parameters like precipitation temperature, pH and relative proportion of the silver and halide ions in the dispersing medium.
• the precipitation is commonly conducted on the halide side of the equivalence point which is defined as 'the point at which the silver and halide ion activity is equal'.
• the silver halide emulsions of the current invention are prepared in the presence of compounds which can be occluded in the crystal structure.
• a compound also called dopant
• the dopant can be distinguished from the metal-complex introduced in the emulsion as an additive by EPR- or ENDOR-techniques.
• the EPR-technique and sample preparation is described in US-A 5,457,021 by Olm et al and by H.Vercammen, T.Ceulemans, D.Schoenmakers, P.Moens and D.Vandenbroucke in Proc.
• a lot of parameters like sensitivity, gradation, pressure sensitivity, high or low intensity reciprocity failure, stability, dye desensitization, and several other sensitometric aspects of a photosensitive silver halide emulsion can be modified by selection of the dopant, including its concentration, its valency and location in the crystal in case of incorporation of the single metal ion.
• the dopant utilized in accordance with the present invention is a transition metal complex which can be defined by the general formula (1) as described hereinbefore.
• Dopants which can be utilised with respect to the objects of the present invention should be incorporated in the silver halide crystals in such a way that they satisfy equation (I) hereinbefore. It is important to know that the lowest value of 'FORM' is equal to zero. This actually happens if a low amount of dopant is located in the extreme center of the crystal or in the contrary almost reaches its surface.
• Introducing one or more dopants in the silver halide emulsion normally tends to increase the gradation of the image-forming element comprising the said emulsion after subsequent illumination and processing. It is frequently accompanied by a decrease in photographic sensitivity. This characteristic is used advantageously in photosensitive image-forming elements for roomlight or daylight operations.
• the location of the dopant plays a dominant role in the fine tuning of the sensitometric characteristics of the material comprising the emulsion containing one or more dopants. It is utilised advantageously in several inventions where the dopant is non-uniformly distributed in the silver halide crystal.
• the dopants according to the general formula (1) in the photosensitive silver halide crystals of the present invention leads to an image-forming element with improved quality with respect to gradation and sensitivity if the conditions for the location and concentration of the dopant are satisfied as stated in the equations (I) and (II) of the present invention. That means that the dopants should be incorporated in the center of the crystals starting almost from the center up to 95% of the average diameter of the emulsion crystals, but preferable up to not more than 75%, and more preferably up to max 50% of the average crystal diameter of the emulsion crystals. It is important to know that the doping procedure always can start just after ending the nucleation step in order to avoid interference of dopants in the formation of the nuclei. Preferably this corresponds with addition of the said dopants after having precipitated about 3 % of silver halide, more preferably about 5 %.
• Dopants which can be used for this invention according to formula (1) are essentially those which act as a deep and permanent electron trap in a silver halide crystal and which satisfies (as taught already before) two conditions: the LUMO of the incorporated molecular entity should be at least 0.5 eV below the conduction band of the silver halide crystal, and the trapping life-time at room temperature should be longer than 0.2 seconds (see R.S.Eachus, M.T.Olm in 'Cryst.Latt.Def.and Amorph.Mat.', 1989(18)297-313).
• the LUMO is defined as the 'lowest unoccupied molecular orbital' of the related complex which can trap an electron from the conduction band (see D.F.Shriver, P.W.Atkins, C.H.Langford in "Inorganic Chemistry'- Oxford Univ.Press (1990), Oxford-Melbourne-Tokyo). Examples of these traps can be find in EP-A 0 606 895, EP-A 0 415 481, US-A 4,835,093 and in US-A 5,348,850.
• the doping procedure itself can normally be executed at any stage during the grain growth phase of the emulsion preparation where the reactants are added to the reaction vessel in the form of solutions of silver and halide salts or in the form of preformed silverhalide nuclei or fine grains which easily dissolve in the precipitation medium. It is important to know that the dopants can also be added in an indirect way by addition of a dispersion containing very fine soluble silver halide grains or nuclei comprising the dopant.
• the individual reactants can be added through surface or subsurface delivery tubes by hydrostatic pressure or by an automatic delivery system for maintaining the control of pH and/or pAg in the reaction vessel and of the rate of the reactant solutions introduced in it.
• the reactant solutions or dispersions can be added at a constant rate or a constantly increasing or fluctuating rate, if desired in combination with stepwise delivery procedures. More details about the possible ways in making a silver halide emulsion which can be principally used in practizising this invention are summarized in Res.Discl.,38957 (1996)591-639 section I-C.
• the solution containing the dopants is preferentially introduced via a third jet, in a zone in the reactor where the compounds are rapidly incorporated in the growing microcrystals.
• the advantage of the use of a third jet is that a solvent can be used for the given dopant which is most suitable for the stability of that compound. Further the temperature of the dopant solution can be adjusted in order to maximize the stability too. The most stable conditions for the dopant solution are tested by UV-VIS absorption.
• the third jet itself can be adjusted automatically or manually.
• the dopant can be added at a constant rate or at any rate profile as for instance in JP-A 03 163 438 wherein the dopant is occluded in two different concentrations in the silver halide grains of a direct positive emulsion having the highest concentration closest to the grain centre.
• This patent describes a method to get a silver halide emulsion with improved gradation without paying attention to the sensitivity level which in the contrary is also the target of the present invention.
• the photographic emulsions prepared in this way contain silver halide crystal comprising chloride, bromide or iodide alone or combinations thereof.
• Other silver salts which can be incorporated in a limited amount in the silver halide lattice are silver phosphate, silver thiocyanate, silver citrate and some other silver salts.
• the chloride and bromide halide can be combined in all ratios to form a silverchlorobromide salt.
• Iodide ions however can be coprecipitated with chloride and/or bromide ions in forming a iodohalide with an iodide amount which depends on the saturation limit of iodide in the lattice with the given halide composition; this means up to a maximum amount of about 40 mole percent in silver iodobromide and up to at most 13 molevig in silver iodochloride both based on silver.
• the composition of the halide can change in the crystal in a continous or discontinous way.
• Emulsions containing crystals composed of various sections with different halide compositions are used for several photographic applications.
• Such a structure with a difference in halide composition between the center and the rest of the crystal what is called 'core-shell'-emulsion) or with more than two crystal parts differing in halide composition (called a 'band'-emulsion) may occur.
• the changes in halide composition can be realised by direct precipitation or in an indirect way by conversion where fine silver halide grains of a certain halide composition are dissolved in the presence of the so-called host grains forming a 'shell' or 'band' on the given grain.
• the crystals formed by the methods described above have a morphology which can be tabular or non-tabular like cubic, octahedral, etc.
• the aspect ratio ratio of equivalent circular diameter to thickness
• the major faces of the formed tabular grains can have a ⁇ 111 ⁇ or a ⁇ 100 ⁇ -habitus the structure of which is (respectively) stable or has to be stabilised (for instance by a 'habitus modifying agent').
• the class of non-tabular grains there are a lot of possibilities which can be divided in the more regular shaped crystals or the crystals with a mixed crystal habit.
• the photographic emulsion of the present invention contains chloride, bromide and iodide as well, preferable chloride and bromide, and most preferred chloride without excluding the presence of the other halides.
• the present invention is suitable for an application in high speed camera-films, in radiographic materials, in graphic art films, in color paper and in others. Therefore a great variety of halide combinations should be covered.
• the chloride containing silver halides as AgClBrI, AgClI and AgClBr the prefered chloride concentration is at least 10 mol% and most prefered not less than 50 mol% which conditions are also encountered in many other silver halide photographic systems like those which are described e.g. in EP-A 0 264 288 and EP-A 0 552 650.
• the present invention is applicable to crystals comprising any combination of halides which can even occasionally exist together with other silver salts as mentioned above. It is important to note that physical grain structures with two or more different halide compositions in one crystal can be used in combination with partially doping according the present invention. It is also interesting to know that the central part of the crystal doped according to the present invention does not necessarily need to cover the central part(s) of the same crystal which are distinguished from the other parts of the crystal by a difference in halide composition. This means that a internally doped crystal can match more than one crystal part with different halide compositions.
• the emulsions can include silver halide grains of any conventional shape or size. Specifically the emulsions can include coarse, medium or fine silver halide grains.
• the silver halide emulsions can be either monodisperse or polydisperse after precipitation.
• dopants which are deep electron traps as described by formula (1)
• other dopants can be added to the silver halide emulsion. These are essentially introduced because of their specific influence on the photographic characteristics.
• dopants such as IrCl 6 3-
• dopants resulting in a non-permanent trapping behaviour can be a shallow electron trap (such as Ru(CN) 6 2- ) (see Res.Discl.,36736 (1994)657.), or a recombination or hole trapping center.
• These dopants are essentially all those not obeying the conditions for a deep electron trap.
• the silver halide emulsions of this invention which are prepared in one of the ways described hereinbefore contain crystals which have a spherical equivalent diameter (SED) of not more than 1.0 ⁇ m but preferable less than 0.5 ⁇ m.
• SED spherical equivalent diameter
• the spherical equivalent diameter (SED) of the crystal represents the diameter of the sphere which has the same volume as the average volume of the silver halide crystals of the said emulsion.
• the emulsions can be surface-sensitive emulsions which form latent images primarily on the surface of the silver halide grains or they can be emulsions forming their latent-image primarily in the interior of the silver halide grain. Further the emulsions can be negative-working emulsions such as surface sensitive emulsions or unfogged internal latent image-forming emulsions. However direct-positive emulsions of the unfogged, latent image-forming type which are positive-working by development in the presence of a nucleating agent, and even pre-fogged direct-positive emulsions can be used in the present invention.
• the silver halide emulsions can be surface-sensitized by chemical sensitization which can be done in many different ways, in presence of a chalcogen as sulfur, selenium or tellurium, in presence of a noble metal as for instance gold or in combination with a chalcogen and noble metal.
• a sulphur sensitizer can be added in form of a dispersion of solid particles as has been described in EP-A 0 752 614. This can also be done by reduction sensitization if desired combined with the chalcogen/noble metal-sensitization.
• the presence of certain 'modifying' agents as for instance spectral sensitizers which can optimize the chemical sensitization process are often used. A complete description of all the different possibilities with respect to this subject can be found in Res.Discl.,38957(1996), section IV.
• the silver halide emulsions are spectrally sensitized with dyes from different classes which include polymethine dyes comprising cyanines, merocyanines, tri-, tetra-and polynuclear cyanines and merocyanines, oxanols, hemioxanols, styryls, merostyryls and so on.
• dyes from different classes which include polymethine dyes comprising cyanines, merocyanines, tri-, tetra-and polynuclear cyanines and merocyanines, oxanols, hemioxanols, styryls, merostyryls and so on.
• more than one spectral sensitizer may be used in the case that a larger part of the spectrum has to be covered.
• the photographic elements comprising the said silver halide emulsions can include various compounds which should play a certain role in the material itself or afterwards in the processing, finishing or warehousing the photographic material. These products can be stabilizers and anti-foggants (see Res.Discl., 38957(1996) section VII), hardeners (see Res.Discl.,38957(1996) section IIB), brighteners (see Res.Discl.,38957(1996) section VI), light absorbers and scattering materials (see Res.Discl.,38957(1996) section VIII), coating aids (see Res.Discl.,38957(1996) section IXA), antistatic agents (see Res.Discl.,38957(1996) section IXC), matting agents (see Res.Discl.,38957(1996) section IXD) and development modifiers (see Res.Discl.,38957(1996) section XVIII).
• the silver halide material can also contain different types of couplers, which can be incorpated as described in Res
• the photographic elements can be coated on a variety of supports as described in Res.Discl.,38957(1996) section XV and the references cited therein.
• the photographic elements can be exposed to actinic radiation, specially in the visible, near-ultraviolet and near-infrared region of the spectrum, to form a latent image (see Res.Discl., 38957(1996) section XVI).
• This latent-image can be processed in order to form a visible image (see Res.Discl.,38957 (1996) section XIX). While the invention is specially focussed on Cl-containing photosensitive silver halide materials, automatic processing is advantagely used in order to get rapid and convenient processing. In order to prevent the disadvantages (as for instance the formation of silver sludge) of automatic processing these materials a preferred method of processing is described in EP-A 0 732 619.
• the developer mentioned in the last reference contains a combination of hydrochinon, an auxiliary developing agent, ascorbic acid or one of its isomers or derivatives, and a small amount of a thiocyanate salt. In more general terms this has already been described for silver halide systems as those mentioned e.g.
• EP-A 0 552 650 and EP-A 0 752 614 But it is recommended to apply the method and to use the various ascorbic acid analogues as described in EP-A 0 732 619, which is incorporated herein by reference.
• Processing to form a visible dye image for colour materials means contacting the element with a colour developing agent in order to reduce developable silver halide and to oxidize the colour developing agent which in turn normally reacts with the coupler to form a dye (see Res.Discl.,38957(1996) section XX)
• Solution A1 gelatin 75 g demineralised water 1500ml AgNO 3 0.04g
• Solution A2 AgNO 3 750g demineralised water 1500ml
• Solution A3 NaCl 257.7g demineralised water 1500ml
• Dot1 NaCl 225g acetic acid 5ml demineralised water added to make 1 l K 2 [RuCl 5 (NO)] 1.372 10 -3 g
• the pH of the solutions A1 and A3 was brought to a pH of 2.8 using a sulphuric acid solution.
• the solutions A2 and A3 were kept at room temperature, while solution A1 was heated to 50 degree C.
• the pAg was set to 7.05 using a sodium chloride solution.
• the thus prepared silver chloride emulsion has a homodisperse grain size distribution, having an average grain size of 0.42 ⁇ m and a variance of about 15% in grain size.
• Emulsions A2 to A5 were prepared in the same way, while the addition of 159 ml of the solution Dot1, containing a Ru- complex, to solution A1 was carried out at a constant rate using a third jet at different moments during the precipation.
• the position of the dopant in the emulsion grains is expressed as the percentage of the crystal volume reached at the moment where the addition of the third jet is started and the percentage of the crystal volume at the moment where the addition of the dopant solution is stopped.
• the location of the dopants, the grain diameter d, the diameter d 1 of the sphere containing the dopant situated as far as possible from the grain centre, the value of the parameter FORM [see formula (II)] and the concentration of th dopant are shown in table A.1.
• the silver chloride emulsions were subsequently ripened at a pAg and pH equal to 7.9 and 4.6 respectively, with a gold tetrachloride solution (5 10 -7 mole/mole Ag) and a dimethylcarbamoylsulfide compound (10 -6 mole/mole Ag) at 50 degrees C for 150 minutes. These emulsions were spectrally sensitized with a blue sensitizer.
• the pH was adjusted to a value of 5.2 afterwards.
• Location and concentration of the RuCl 5 NO-dopant in an AgCl crystal Location Conc. (10 -9 mole/mole Ag) d ( ⁇ m) d 1 ( ⁇ m) FORM A1 - - 0.420 - 0 A2 5-100% 128 0.422 0.422 0 A3 5-80% 128 0.424 0.394 20 A4 5-20% 128 0.429 0.251 21 A5 80-100% 128 0.423 0.423 0
• the emulsions were coated on a substrated PET base in an amount of 4 g of gelatin/m 2 and 2.5 g Ag/m 2 .
• a layer containing gelatin (0.5 g per m 2 ), a vinylsulphonic hardener and surfactants were coated on top of the emulsion layer.
• the photographic materials were image-wise exposed through a step-wedge original using a 10 -3 sec Xe flash.
• the exposed photographic materials were developed in a G101 commercial developer using a Rapiline 66-3 machine at 35 degree C for 25 sec, and fixed at 33 degree C for 25 sec in a G 333c commercial fixer to which a hardener (Aditan) was added. All these commercial products are trademarket names from Agfa-Gevaert.
• the fog level is low for all the materials, i.e. 0.03 to 0.04.
• a positive number indicates that more energy is needed by exposing in order to obtain the same optical density.
• a more positive number is indicative for a less sensitive emulsion.
• the contrast is measured around this sensitivity point (between 25% and 75% of density).
• the relative contrast is expressed as the ratio (in percentage) of the contrast of the doped emulsion versus the non-doped emulsion.
• the sensitivity and contrast in the shoulder portion of the sensitometric curve are derived in a similar way.
• the sensitometric parameters are given in table A.2. The advantages of the actual invention becomes most evident in the experiments where values of the parameter FORM obeye equation (I), especially in the shoulder of the sensitometric curve.
• the 'normal'- and the 'shoulder'-contrast are significantly influenced by the location of the dopant in the microcrystals.
• Solution B1 gelatin 75 g demineralised water 1500ml AgNO 3 0.04g
• Solution B2 AgNO 3 750g demineralised water 1500ml
• Solution B3 NaCl 257.7g demineralised water 1500ml
• Dot2 NaCl 225g acetic acid 5ml demineralised water added to make 1 l K 2 [RuCl 5 .(NO)] 6.9 10 -3 g
• the pH of the solutions B1 and B3 was brought to a pH value of 2.8 using a sulphuric acid solution.
• the solutions B2 and B3 were kept at room temperature, while solution B1 was heated to 50 degree C.
• the pAg was set to 7.05 using a sodium chloride solution.
• Solution B2 was added to solution B1 at a constant rate at 5 ml/min., while solution B3 was added at a rate in order to keep the pAg constant during 3 minutes. Afterwards the addition rate for solution B2 was slighlty raised up to 6.2 ml/min. while the addition rate of solution B3 was varied in order to raise the pAg over 0.5 units in 4 minutes.
• Solution B2 was further added at an accelerated rate of 0.202 ml/min., while solution B3 was added at a rate sufficient to keep pAg constant.
• the emulsion was diafiltrated afterwards to a volume of 2.5 l and desalted by ultrafiltration at constant pAg of 7. After the washing procedure 150 g of gelatin was added to the precipitate and demineralised water was added in order to get a total weight of 3.75 kg.
• the thus prepared silver chloride emulsion has a homodisperse grain size distribution, having a mean grain size of 0.42 ⁇ m and a variance of about 15% in grain size.
• Emulsions B2 to B3, also containing AgCl were prepared in the same way, except for the addition of 15.9 ml of the solution Dot2, containing the same Ru-complex as in example 1, which was added to solution B1 at a constant addition rate using a third jet at different moments during the precipation.
• the position of the dopant in the emulsion grains is expressed as the percentage of the crystal volume at the moment where the addition of the third jet is started and the percentage of the crystal volume at the moment where the addition of the dopant solution is stopped.
• the location of the dopants and the grain size are shown in table B.1.
• the AgBr-emulsions B4 to B6 were prepared in a similar way : Solution B4 : gelatin 75 g demineralised water 1500ml AgNO 3 0.04g Solution B5 : AgNO 3 750g demineralised water 1500ml Solution B6 : KBr 524.8g demineralised water 1500ml
• the pH of the solutions B4 and B6 was brought to a pH of 2.8 using a sulphuric acid solution.
• the solutions B5 and B6 were kept at room temperature, while solution B4 was heated to 50 degree C.
• the pAg was set to a value of 6.4 with a potasium bromide solution.
• Solution B5 was added to solution B4 at a constant rate of 1.25 ml/min.
• Emulsions B5 and B6 were prepared in the same way as emulsion B4, except that these emulsions were doped with a Ru complex as indicated in table B.1.
• the addition of 17.9 ml of the dopant solution Dot2 to solution B4 during the precipition of the AgBr was carried out by using a third jet.
• the silver chloride emulsions were subsequently ripened at a pAg and pH equal to 7.9 and 4.6 respectively, with a gold salt (5 10 -7 mole/mole Ag) and a sulfur compound (10 -6 mole/mole Ag) at 50 degrees C for 150 min.
• the emulsions were further stabilized with triazaindolizine. A part of these emulsions was spectrally sensitized with a green light-absorbing sensitizer.
• the pH was afterwards adjusted to a value of 5.2.
• the emulsions were coated on a substrated PET base in an amount of 4 g of gelatin per m 2 and 2.5 g Ag/m 2 .
• the exposed photographic materials were developed in a G101 commercial developer using a Rapiline 66-3 machine at 35 degree C for 25 sec, and fixed at 33 degree C for 25 sec in a G 333c commercial fixer to which a hardener (Aditan) was added. All the commercial products are trademarket names of Agfa-Gevaert.
• a positive number indicates that more energy is needed in the illumination in order to obtain the same optical density.
• a more positive number is therefor indicative for a less sensitive emulsion.
• the fog level is for all the materials low, i.e. 0.03 to 0.04.
• the contrast is measured around this Sensitometric results of doping an AgCl crystal with a RuCl 5 NO-dopant at different locations.
• Location Dye Relative sens. Relative contrast B1 - no - 100 comp. B2 inner shell no .67 226 invent. B3 outer shell no .87 100 comp. B1 - yes - 100 comp. B2 inner shell yes .75 194 invent. B3 outer shell yes .95 102 comp. sensitivity point (between 25% and 75% of density).
• the relative contrast is expressed as the ratio (in percentage) of the contrast of the doped emulsion versus the none doped emulsion.
• the sensitometric parameters are given in table B.2.
• the silver bromide emulsions were ripened at a pAg and pH equal to 7.8 and 4.6 respectivily, with gold salt (5 10 -6 mole/mole Ag) and sulfur salt (8.6 10 -6 mole/mole Ag) at 50 degrees C for 150 minutes.
• gold salt 5 10 -6 mole/mole Ag
• sulfur salt 8.6 10 -6 mole/mole Ag
• the exposure, processing and sensitometric evaluation of the photographic materials were performed in the same way as described as hereinbefore.
• the sensitometric parameters are given in table B.3 where next to the 'normal' contrast and sensitivity also the values for the 'shoulder' are given.
• the shoulder sensivitiy and contrast are measured in the same way as described hereinbefore in example 1.
• the influence of the location of the dopant on the gradation and sensitivity of the doped emulsion is similar as observed in example 1.
• Solution C1 gelatin 75 g demineralised water 1500ml Solution C2 : AgNO 3 750g demineralised water 1500ml Solution C3 : NaCl 257.7g demineralised water 1500ml Solution C4 : NaCl 228.87g demineralised water 1375ml Sol.
• Dot4 125ml Solution Dot3 : NaCl 250g acetic acid 5ml demineralised water added to make 1 liter Na 3 RhCl 6 .12H 2 O 17.04g Solution
• Dot4 NaCl 250g acetic acid 5ml demineralised water added to make 1 liter Na 3 RhCl 6 .12H 2 O 2.13g
• the pH of the solutions C1 and C3 was brought to a pH of 3.5 using a HNO 3 solution.
• the solutions C2 and C3 were kept at room temperature, while solution C1 was heated to 40 degree C.
• the pAg was set at a value of 7.95 using a sodium chloride solution.
• Solution C2 was added to solution C1 at a constant rate, while solution C3 was added at a rate in order to keep the pAg constant during 3 minutes. Afterwards solution C2 was added at an accelerated rate, while solution C3 was added at a rate sufficient to keep the pAg constant.
• the resulting silver chloride was precipitated by adding a polystyrene sulphonic acid. The precipitate was rinsed several times by using a low concentrated NaCl solution (0.539 mg NaCl per liter demineralised water), and subsequently redispersed by adding 195 g of gelatin to the precipitate and chlorinated water in order to get a total weight of 3.250 kg.
• the so prepared silver chloride emulsion has a homodisperse grain size distribution with a mean grain size of 0.20 ⁇ m and a variance in grain size of about 20%.
• Emulsions C2 and C3 were prepared in the same way.
• the addition of 15.6 ml of solution Dot3 was carried out by using a third jet between the moments that RhCl 6 3- -dopant situated at different locations in an AgCl-crystal.
• Nr mole Rh3+/mole Ag d ( ⁇ m) d 1 ( ⁇ m) FORM C1 none 0 0.206 - 0 C2 6-21% 100 10 -6 0.211 0.125 16469 C3 0-100% 100 10 -6 0.200 0.200 0 respectivily 6 and 21% of the silver was added.
• Emulsion C3 was prepared identical to emulsion C1 except that for the precipitation solution C4 was used instead of solution C3.
• Emulsion specifications are given in Table C.1
• the emulsions were further prefogged. Therefore the pH was adjusted at a value of 7.0 using NaOH and the pAg was set at 7.95 using a chloride solution.
• the pH was adjusted at a value of 7.0 using NaOH and the pAg was set at 7.95 using a chloride solution.
• the pAg was set at 7.95 using a chloride solution.
• 9.676 10 -6 mole thioureumdioxyde was added per mole silver.
• After 15 minutes 1.241 10 -6 mole of a gold salt was added per mole of silver and after another minute 3.23 10 -6 mole of sodium toluenethiosulphonate was added per mole of silver.
• the fogging process was continued for 3 hours at this temperature.
• a nitrobenzimidazole-5(6) desensitizer was added to the emulsions followed by coating on a PET base in an amount of 3.5 g of silver and 2.2 g of gelatin both per m 2 .
• a top layer containing hardener and surfactants was coated on the emulsion layer.
• the photographic materials were image-wise exposed through an step-wedge original using a QL 100 LI equipement. Using a PRINTON LI the illumination time was adjusted to 150 units.
• the exposed photographic materials were developed in a G101 commercial developer using a Rapiline 66-3 machine at 35 degree C for 25 sec, and fixed at 33 degree C for 25 sec in a G 333c commercial fixer to which a hardener (Aditan) was added. All these commercial products are trademarket names of Agfa-Gevaert. The practical evaluation of the relative speed and contrast were performed as described hereinbefore.
• the sensitometric parameters are given in table C.2 Sensitometric results of AgCl-emulsions in relation with different locations of a Rh-salt in the crystal.
• Solution D1 gelatin 25 g demineralised water 1000ml Solution D2 : AgNO 3 250g demineralised water 500ml Solution D3 : NaCl 85.91g demineralised water 500ml Solution Dot5 : NaCl 58.44g acetic acid 5ml demineralised water added to make 1 liter Na 3 RhCl 6 .12H 2 O 17.04g
• the pH of the solutions D1 and D3 was brought to a pH of 3.0 using a HNO 3 solution.
• the solutions D2 and D3 were kept at room temperature, while solution D1 was heated to 40 degrees C.
• the pAg was adjusted at 8.24 by using a sodium chloride solution.
• Solution D2 was added to solution D1 at a constant rate, while solution D3 was added at a rate in order to keep the pAg-value constant during 3 minutes. Afterwards solution D2 was added at an accelerated rate, while solution D3 was added at a rate sufficient to keep the pAg constant.
• the addition of 2.5 ml of dopant solution Dot5 was carried out by using a third jet between the moment that the first 10% of silver was reacted and te end of the precipitation. The resulting silver chloride was precipitated by adding a polystyrene sulphonic acid.
• the precipitate was rinsed several times by using a low concentrated NaCl solution (0.539 mg NaCl per liter demineralised water) and subsequently redispersed by adding 50 g of gelatin to the precipitate and chlorinated water in order to get a total weight of 1.250 kg.
• the so prepared silver chloride emulsion has a homodisperse grain size distribution with a mean grain size of 0.14 ⁇ m and a variance in grain size of about 24%.
• Emulsions D2 and D3 were prepared in the same way.
• the addition of 2.5ml of solution Dot5 was carried out by using a third jet between the moments that respectivily 10 and 20% of the silver was added.
• emulsion D3 was it between the moments that 90 and 100% of the silver was added.
• Emulsion specifications are given in table D.1 Location and concentration of a Rh-dopant situated in an AgCl-crystal.
• the photographic materials were image-wise exposed for 10 seconds through an step-wedge original using a CDL 1030 equipement on level 1.
• the development was carried out as described in example 3.
• the relative speed is the logarithm of the ratio of the energy of the illumination needed to obtain an optical density equal to the 0.3 above fog level, relative to the illumination energy needed to get the same density for the emulsion with the dopants homogeneously spread in the crystal between 10 and 100% of the crystal volume.
• the contrast is measured in the foot of the sensitometric curve between reference densities 0.05 and 0.3 above fog level.
• the relative contrast is expressed as the ratio in percentage of the contrast of the doped emulsion versus the emulsion with the dopants homogeneously spread in the crystal between 10 and 100% of the crystal volume.
• sensitometric parameters are given in table D.2 As can be seen in this experiment and as expected from the value of the parameter FORM (equation II), the activity of the electron trap increases rapidly by 'moving' the dopant from the outer regions to the center of the crystal. Sensitometric results of a Rh-doped AgCl-emulsion as a function of the location of the dopant. Dopant-solution Location Rel. Sens. Rel.

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