JPH09509756A - High speed photographic emulsion - Google Patents

Abstract

(57) Summary: Photographically sensitive tabular grains in which the tabular grains have a maximum surface iodide concentration along their edges and where the surface iodide concentration in the corners is lower than elsewhere along the edges. An emulsion is disclosed. Tabular grains contain dopants that can provide shallow trap sites.

Description

Detailed Description of the Invention High speed photographic emulsion   The present invention relates to photographic emulsions and methods for making them.   U.S. Pat. No. 4,439,520 (Kofron et al.) Discloses a tabular grain emulsion. Provide various photographic advantages, including improved photographic speed and speed-granularity relationships. That was shown first.   U.S. Pat. No. 4,433,048 (Solberg et al.) Describes the perimeter of tabular grains. A tabular grain emulsion with a high iodide concentration adjacent to the edge of Photographic sensitivity is higher than comparable tabular grain emulsions that have Was first shown. Subsequently, as shown below, others have determined that the highest iodide levels A tabular grain emulsion with a non-uniform iodide distribution occurring at the surface location was investigated: Rice National Patent No. 4,883,748 (Hayakawa), US Patent No. 5,061,609 and No. 5,061,616 (Piggin et al.), US Pat. No. 5,132,203 (Bell et al.), US Pat. No. 5,206,133 (Bando) and US patents. Xu 5,314,798 (Brust et al.).   U.S. Pat. No. 4,210,450 (Corben) alternates with silver chloroiodobromide. After performing precipitation with ammonia and introducing ammonium iodide, Discloses that a shelled conversion halide emulsion is prepared by repeating ing. The resulting emulsion is said to be useful for color diffusion transfer, but No performance advantage has been stated or disclosed.   U.S. Pat. No. 4,937,180 (Marchetti et al.) Silver halide grains containing iodide Hexahedral distribution of at least four cyanide ligands with bismuth, ruthenium or osmium Disclosed are emulsions formed in the presence of a coordination complex.   U.S. Pat. No. 5,268,264 (Marchetti et al.) Is optional with bromide. Silver halide grains having a {111} crystal face containing iodide in the An embedded system formed in the presence of a hexacoordinated complex of at least three cyanide ligands. Emulsions containing gels are disclosed.   US Pat. No. 5,132,203 (Bell et al.) Describes tabular silver halide grains. Of the host layer containing at least 4 mol% of iodide and 2 mol% of iodide. Disclosed is an emulsion formed from a multiplicity of thin layers. Multiple layers Each includes a surface layer forming one of the major surfaces and a Group VIII group 4 or 5 metal. Immediately below the surface containing a hexacoordinated complex with at least three cyanide ligands And an inner layer surface.   Research Disclosure, Volume 367, November 1994, Item 36736 is a dopant that forms a shallow electron trap (SET) site Is disclosed. Research Disclosure is located in Ha Nmpshire P010 7DQ Emsworth 12 North Street Dudley -Kenneth Mason Publications, Inc. Has been issued by   According to one aspect of the present invention, it comprises a dispersion medium and silver halide tabular grains, The silver halide grains have a face centered cubic crystal lattice of rock salt type structure and the tabular grains Photograph containing iodide adjacent to the surface forming the child's edges and corners A sensitive emulsion wherein said tabular grains have a maximum surface area along their edges. With iodide concentration, where the surface iodide concentration in the corners is elsewhere along the edge Lower than, present at a total concentration of less than 500 mppm, based on silver, and surface concentration last Electron trap limited to less than 100 mppm based on 5% silver deposited on Provided is an emulsion characterized by containing a dopant capable of providing sites Is done. Brief description of the drawings   1 and 2 show the edge-to-edge (see line EE below) of tabular grains. I) or between corners (see line C-C below) for iodide concentration. Shows the degree distribution,   FIG. 1 is an iodide distribution obtained from a tabular grain emulsion satisfying the requirements of the present invention. ,   FIG. 2 is an iodide distribution obtained from ordinary tabular grains.   Quite unexpectedly, surfaces (especially edges) in silver halide tabular grain emulsions And corner) Iodide placement was previously neither recognized nor attempted. By controlling with, the level of photographic sensitivity is increased without causing deterioration of granularity. I found that I can do it. Specifically, tabular grains are the largest surface iodides. Concentration along the edge and surface iodide concentration in the corner Lower than the place. "Surface iodide concentration" means 0.02μ from the tabular grain surface. Mean iodide concentration within m.   At the beginning of the preparation of emulsions satisfying the requirements of the invention, tabular The grains show (1) face centered cubic crystal lattice of rock salt type structure, (2) surface iodide concentration Can be any of the conventional tabular grain emulsions having a content of less than 2 mol%.   Both silver bromide and silver chloride exhibit a face-centered cubic crystal lattice with a rock-salt structure (space group). It can also be confirmed by the name of the loop (Fm3m). Therefore, the starting tabular grain The offspring can be selected from silver bromide, silver chloride, silver chlorobromide and silver bromochloride. Silver iodide on the rock Does not form face-centered cubic crystal lattice of salt structure (except under conditions not related to photography) However, a small amount of iodide is a face-centered cubic crystallite formed by chloride and / or silver bromide. Pebble salt structure is acceptable. That is, the surface iodide concentration satisfies the above criterion (2). The starting tabular grains also include silver iodobromide, iodosalt Silver iodide, silver iodochlorobromide, silver iodobromochloride, silver chloroiodobromide and silver bromoiodochloride composition, etc. There is.   For silver halide grains or emulsions containing more than one halide, the halogen Compounds are shown in order of increasing concentration.   Suitable for use as a starting emulsion, i.e. satisfying criteria (1) and (2) Ordinary tabular grain emulsions selected from those having {111} or {100} major faces it can. Suitable tabular grain emulsions containing {111} major surface tabular grains are commercially available from US Xu 4,399,215 (Wey), U.S. Pat. No. 4,400,463, 4th , 684, 607, No. 4,713, 320, No. 4,713, 323, No. 5, , 061,617, No. 5,178,997, No. 5,178,998, No. 5, , 183,732, 5,185,239, 5,217,875 and 5,221,602 (Maskasky), U.S. Pat. No. 4,414,306 (Wey et al.), U.S. Pat. Nos. 4,414,310, 4,672,027, 4,693,964 and 4,914,014 (Daubendiek et al.) U.S. Pat. No. 4,425,426 (Abbott et al.), U.S. Pat. No. 4,434. , 226 (Wilgus et al.), U.S. Pat. No. 4,439,520 (Kofro n, et al.), US Pat. No. 4,665,012 (Sugimoto et al.), US Pat. 4,686,176 (Yagi et al.), US Pat. No. 4,748,106 (Hayashi) U.S. Pat. No. 4,775,617 (Goda), U.S. Pat. No. 4,783,39. 8 (Takeda et al.), U.S. Pat. Nos. 4,797,354 and 4,977. 074 (Saito et al.), US Pat. No. 4,801,523 (Tufano), US Patent 4,804,621 (Tufano et al.), US Pat. No. 4,806,46 1 and EPO 0485946 (Ikeda et al.), US Pat. No. 4,853,322 ( Makino et al., US Pat. No. 4,952,491 (Nishikawa et al.), US Pat. No. 5,035. , 992 (Houle et al.), US Pat. No. 5,068,173 (Takehara et al.), US National Patent No. 5,096,806 (Nakamura et al.), US Patent No. 5,147,771, No. 5,147,772, No. 5,147,773, No. 5,171,659, No. 5,210,013 and No. 5,252,453 (Tsaur et al.), US special Xu 5,176,991 (Jones et al.), US Pat. No. 5,176,992 (Maskasky et al.), US Pat. No. 5,219,720 (Black et al.), US Pat. No. 5,238,796 (Maruyama et al.), US Pat. No. 5,250,403 (Antoniades, etc.), EPO0362699 (Zola, etc.), EPO0 460656 (Urabe), EPO0481133, EPO0503700 and EP O0532801 (Verbeek), EPO0515894 (Japan) tan et al.) and EPO 0547912 (Sekiya et al.). Departure milk Emulsions containing {100} major surface tabular grains useful as agents are described in US Pat. 63,951 (Bogg), USA Patent 4,386,156 (Mignot), US Pat. No. 5,264,337 And 5,275,930 (Maskasky), US Pat. No. 5,314, 798 (Brust et al.), US Pat. No. 5,320,938 (House et al.) , EPO 05699971 (Saito et al.) And Japanese Patent Application No. 4-77261. You.   In its simplest form, the starting tabular grains are free of 2 mole% iodide throughout. Fully contained. However, higher levels of iodide inside the tabular grains A lower iodide level that matches the starting tabular grains to criterion (2) Of shells can be used in the practice of the invention.   To improve the sensitivity by modifying the surface iodide of the starting tabular grain emulsion, Start with the usual emulsion precipitation conditions that are convenient to. For example, the introduction of iodide It can begin shortly after the completion of tabular grain emulsion precipitation. Starting tabular grain emulsion prepared in advance However, when introducing it into the reaction vessel later, change the state inside the reaction vessel to the above-mentioned starting level. Conventional tabular grain emulsion preparation parameters taught in the tabular grain emulsion reference patents. Adjust to what is present at the end of the starting tabular grain emulsion precipitation in the meter. Flat plate In the case of a starting tabular grain emulsion in which the tabular grains have {111} major faces, the above-mentioned Kofr The teachings of on, etc. are generally applicable and preferred.   Iodide was introduced as a solute into the reaction vessel containing the starting tabular grain emulsion. You. Any water soluble iodide salt may be used to supply the iodide solute . For example, iodide can be replaced with ammonium, alkali or alkaline earth iodide in water. It can be introduced in the form of a solution.   Instead of providing the iodide solute in the form of an iodide salt, an organic iodide compound Available in form. Compounds of this type can be represented by the formula: (I)                 R-I (In the formula, R represents a monovalent organic component that imparts carbon to the iodide bond). At least Also, a compound showing some water solubility is selected. Therefore, the number of carbon atoms is If the number of carbon atoms is 3 or more, water solubility is preferably promoted. It contains a progressive polar substituent. A wide range of such compounds are known as EPO056141. 5 (Kikuchi et al.). However, Kikuchi et al. The R-I compound was reacted with other specially prepared additives to give a very rapid iodide reaction. However, in the practice of the present invention, iodide is released slowly. Intended to be. This is R-1 compound and gelatin contained in emulsion. Alternatively, it can be achieved by slowly reacting with a gelatin derivative. Accidentally The released organic component reacts with gelatin. Therefore, iodide is It is released without producing by-products that must be removed from the emulsion at. R The reaction of -I compounds with gelatin and gelatin derivatives is described in U.S. Pat. No. 4,942,942. No. 120 (King et al.), King et al. However, it is not concerned with the release of iodide.   Common in the art for introducing iodide during silver halide precipitation Another alternative is to introduce the iodide ion in the form of a silver iodide Lippmann emulsion. You. The introduction of iodide in silver salt form does not meet the requirements of the invention.   In the preparation of the tabular grain emulsion of the present invention, iodide was prepared without introducing silver at the same time. Introduce ions. This allows the iodide ion to enter the face center of the tabular grain in the emulsion. Conditions can be incorporated into the cubic crystal lattice. Iodide in tabular grain crystal lattice structure Driving force for introducing objects Can be understood by considering the following equilibrium relationship: (II) (In the formula, X represents a halide). From the relational expression (II), in equilibrium, silver and halo Most of the genide ions are in the insoluble form, and soluble silver ions (Ag⁺) And halo Genide ion (X^-) Concentration is limited. However, equilibrium becomes dynamic equilibrium That is, a specific iodide is fixed at the right or left position in relational expression (II). It is important to recognize that it is not fixed. Rather, the iodide ion is on the left There is a constant switch between the position and the position on the right.   Ag at any constant temperature⁺And X^-The activity product of is constant at equilibrium and Satisfies the formula: (III)                   Ksp = [Ag⁺] [X^-] (In the formula, Ksp is a solubility product constant of silver halide). Avoiding small impacts The following relations are also widely used to: (IV)           -Log Ksp = pAg + pX (Where pAg represents the negative logarithm of the equilibrium silver ion activity,   pX represents the negative logarithm of the equilibrium halide ion activity). From the relational expression (IV), the value of −log Ksp is large for a certain halide. It is clear that its solubility is very low. Photo halide (Cl, Br And the relative solubilities of I) can be understood by reference to Table I: From Table I, at 40 ° C, the solubility of AgCl is one million times greater than that of silver iodide. On the other hand, in the temperature range shown in Table I, the solubility of AgBr is The range is about 1000 times to 10000 times the degree. Therefore, the iodide ion is Strong equilibrium when introduced into the starting tabular grain emulsion without simultaneous introduction of silver ions. It is already present because of the force that causes iodide ions to be incorporated into the crystal lattice structure. It replaces the more soluble halide ion.   More soluble halide ions in the crystal lattice structure of starting tabular grains. Of all are replaced by iodide, the advantages of the present invention are not realized. If this is When it occurs, iodide is only accommodated to a limited extent in the lattice structure, so The cubic crystal lattice rock salt structure will be destroyed and eventually the tabular shape of the particles will be destroyed . Therefore, the iodide ions introduced form the starting tabular grain emulsion. Especially intended to be limited to 10 mol% or less, preferably 5 mol% or less of the total silver Is done. The minimum amount of iodide introduced is at least 0.5 mol based on starting silver. %, Preferably at least 1.0 mol%.   Iodide ion comparable to the speed used for normal double jet inflow salt addition Pouring into the starting tabular grain emulsion at a rate The incoming iodide ions are not evenly or randomly distributed. Obviously tabular grains The surface of the It is easy to exchange. Furthermore, on the surface of the tabular grains, the halide storage with iodide Replacement occurs preferentially. The surface halide composition in the starting tabular grains is uniform Then, the crystal lattice structure at the corner of the tabular grain is most halide ion. Of the tabular grains are then displaced. Of tabular grains The major surface is the least susceptible to halide ion substitution. Halide ion introduction At the end of the process (including the required introduction of iodide releasing agent), the highest in tabular grains Iodide concentration occurs in the part of the crystal lattice structure forming the tabular grain corners. It is thought to be.   The next step in the manufacturing process is to selectively remove iodide ions from the tabular grain corners. To remove. This is achieved by introducing silver as a solute. That is, silver is introduced in a soluble form similar to that described above for iodide incorporation. In a preferred embodiment, the silver solute is deposited by conventional single jet or double jet deposition. It is introduced in the form of an aqueous solution similar to. For example, silver is preferably an aqueous silver nitrate solution. To introduce. No further iodide ions are introduced during the introduction of silver.   The amount of silver introduced is the iodide introduced in the starting tabular grain emulsion during the iodide introduction process. More than things. The amount of silver introduced is, on a molar basis, the iodide introduced in the iodide introducing step. 2 to 20 times that of the compound (most preferably 2 to 10 times).   When introducing silver ions into high-corner iodide tabular grain emulsions, the halide The ions are in a dispersion medium that is available to react with silver ions. Halide One source of ions comes from relation (II). However, the halide The main source of ions is that photographic emulsions contain a stoichiometric excess of halide ions. Inadvertently prepared and maintained in situ⁺To avoid being reduced to Ag ° Better to avoid increasing the minimum optical density observed following photographic processing It is due to.   When the introduced silver ions precipitate, the silver ions remove iodide ions from the dispersion medium. Remove. In order to restore the equilibrium relationship with iodide ions in solution, the grain The silver iodide at the corners (see relational expression II above) allows iodide ions to turn into the corners of the grain. From the solution into the solution where it reacts with further added silver ions. next, Stoichiometric excess of halide ions as well as silver and iodide ions The chloride and / or bromide ions that were present due to redeposition.   Avoid direct reduction of silver ions by depositing directly on the edges of tabular grains. Halide ions to avoid thickening of the tabular grains. Is maintained in stoichiometric excess, and the halide ion concentration in the dispersion medium is changed to tabular grains. Keep in what is known to be favorable for offspring growth. For example, high (> 50 m %), The pBr of the dispersion medium should be at least 1.0. maintain. In the case of high (> 50 mol%) chloride emulsions, chloride ions in the dispersion medium The molarity of is maintained above 0.5M. The amount of silver introduced and the initial amount in the dispersion medium Depending on the amount of excess rogenide ion, bromide and / or chloride may be added during the introduction of silver ion. Additional addition of product ions may be required. However, silver bromide and / or salt Due to the much lower solubility of silver iodide compared to silver iodide, bromide and / or Is not affected by the introduction of chloride ions. Interaction occurs.   As described above, the introduction of silver ions eventually causes the silver ions to become tabular grains. Deposit on the edge of. At the same time, iodide ions are removed from the tabular grain corners. To the edge. Iodide ion As is replaced by tabular grain corners, the tabular grain corners become uneven Therefore, the latent image forming efficiency is increased. In tabular grains, the corner surface iodide concentration Degree is the highest surface iodide concentration found in the grain, i.e. At least 0.5 mol%, preferably less than the highest surface iodide concentration Is also preferably 1.0 mol% lower. As can be seen in the examples given below, The portion of iodide located adjacent to the grain corner in the Maru Typically, the concentration of surface iodide that remains adjacent to the corner of the grain is The final surface iodide concentration adjacent to the major surface of the tabular grains is approached.   If the starting tabular grain emulsion does not contain iodide, the minimum amount during the iodide introduction step If you want to introduce the highest amount of silver during the subsequent silver ion introduction step, For example, the minimum level of iodide in the obtained emulsion should be as low as 0.4 mol%. Can be. The higher the iodide introduction level, the lower the subsequent silver ion introduction level. And / or lower levels of iodide initially present in the starting tabular grains Much higher levels of iodide can be present in the tabular grain emulsions of this invention. The present invention Preferred emulsions having a total iodide level of 20 mol% or less are most preferred. It is preferably 15 mol% or less. The preferred minimum total iodide concentration is 1.0 mol%. For photography, iodide was used to increase native blue sensitivity. To release iodide ions during development due to the inter-image effect, etc. Due to the photographic advantages of higher iodide concentrations, higher total iodide concentrations are preferred. New Rapid access, such as typically performed in medical radiography In the case of treatment, the total concentration is preferably less than 5 mol%, optimally less than 3 mol%. Keep full.   In the preferred emulsions according to this invention tabular grains are the total grain projected area Account for more than 50%. Tabular grains are most preferred for total grain projected area. Account for at least 70%, optimally at least 90%. Photographed so that it can be identified The tabular grains satisfying the above iodide distribution requirement capable of increasing the true sensitivity are , May be present in any proportion. All tabular grains were obtained by the same emulsion precipitation. When present, at least 25% of the tabular grains exhibit the iodide distribution described above. . Preferably, tabular grains accounting for at least 50% of total grain projected area are The iodide distribution required by light is shown.   The preferred emulsions according to the invention are relatively monodisperse. In quantitative terms, Preferably, the coefficient of variation of equivalent circular diameter (ECD) is based on the total grain population of the precipitated emulsion. (COV) is less than about 30%, preferably less than 20%. The ECD COV is , COV_ECDAlso called. COV_ECDOf less than 10% (eg US High unit such as Xu 5,210,013 (disclosed by Tsaur et al.) By using a starting tabular grain emulsion_ECDLess than 10 It is possible to prepare certain emulsions according to the invention. US Pat. No. 5,147,7 71, 5,147,772, 5,147,773 and 5,171,6 No. 59 (Tsaur et al.) Tabular grain emulsions of silver bromide and silver iodobromide are preferred species. Are the starting tabular grain emulsions of the class. US Pat. No. 5,334,469 (Sutto n is the tabular grain thickness (COV_t) With a COV of less than 15% The improvement of the agent is disclosed.   The average tabular grain thickness (t), ECD, aspect ratio (ECD / t) and flatness (ECD / t²(In the formula, the measurement units of ECD and t are μm)) , Can be selected within any convenient conventional range. The tabular grains are preferably The average thickness is less than 0.3 μm. Ultrathin (average thickness <0.07μm) tabular grains Emulsion Intended. A photographically useful emulsion should have an average ECD of 10 μm or less. However, in practice, average ECD's rarely exceed 6 μm. Relatively low feeling For any photographic application, any of the emulsions of the present invention that meet the average aspect ratio requirements. The minimum average ECD of these can also be used. To be regarded as a flat plate, Each grain must have parallel major faces and an average aspect ratio of at least 2. It is preferable to require. Therefore, the average aspect ratio of emulsions should always exceed 2. , Preferably more than 5, most preferably more than 8. Typically tabular grain milk The average aspect ratio of the agent is less than 75, but an extremely high average aspect ratio of 100 or more. Ect ratio is intended.   The grain structure described above provides an unexpectedly high level of photographic efficiency. That is, feeling The degree-granularity relationship (see Kofron et al. Above) is excellent. Embodiment of the present invention The purpose of the purpose is a dopant capable of forming a shallow electron trap site (hereinafter referred to as "SET dopant"). -Also referred to as "panto") to increase granularity by including it in specific density and position Without further increasing the sensitivity of the emulsion, thereby improving the overall efficiency.   Recently, an extensive description of the structural requirements for SET dopants has been given above in Research. ch Disclosure, first done in item 36736. light When the particles are absorbed by the silver halide grains, electrons (hereinafter referred to as “photoelectrons”) are generated. From the valence band of the silver rogenide crystal lattice to its conduction band, holes in the valence band (below , "Photo hole") is formed. To form a latent image part in the grain , Multiple photoelectrons generated in a single imagewise exposure are some silver ions in the crystal lattice. Must be reduced to form small clusters of Ag ° atoms. Latent image shaped To the extent that photoelectrons are dissipated by competing mechanisms before they can be formed. Photographic sensitivity of silver halide grains is reduced. For example, if the photoelectrons return to the photohole, , That energy Ghee is dissipated without contributing to latent image formation.   Doping with silver halide has contributed to the efficient use of photoelectrons for latent image formation. It is intended to cause a shallow electron trap to be applied inside. This is face-to-face In the tetragonal lattice, the net valence of the ion (single or multiple) substituting in the lattice Achieved by incorporating a dopant that exhibits a net valence that is more positive than You. For example, in the simplest form possible, the dopant is in the crystal lattice structure. Silver ion (Ag⁺) May be a polyvalent (+2 to +5) metal ion replacing You. For example, monovalent Ag⁺A local net positive charge when the cation is replaced by a divalent cation. The crystal lattice with is left. This locally reduces the energy in the conduction band. . The amount by which the local energy of the conduction band is reduced is described in J. Mol. F. Hamilton, Adv ances in Physics, Vol. 37 (1988), p. 395 and Excitonic Processes in Solids, M.D. Ueta , H .; Kanazaki, K .; Kobayashi, Y .; Toyozawa and E . Springer-Ve, Hanamura, (1986), Berlin The effective mass approximation as described on page 359, published by Rlag, may be applied. You can guess it with. If the silver chloride crystal lattice structure is +1 net positive due to doping If it receives a charge, its conduction band energy is about It decreases by 0.048 electron volt (eV). If the net positive charge is +2, the shift is about It is 0.192 eV. In case of silver bromide crystal lattice structure, it is provided by doping +1 net positive charge locally reduces conduction band energy by about 0.026 eV Is done. For a net positive charge of +2, the energy is reduced by about 0.104 eV. It is.   When photoelectrons are generated by absorbing light, the photoelectrons are At the position of the conduction band energy attracted by the net positive charge to the dopant site. It is temporarily retained (ie bound or trapped) with a binding energy equal to the partial reduction. Dopants that cause local bending of the conduction band to lower energies drive photoelectrons. -The binding energy that is retained (trapped) at the punt site is the electron at the dopant site. It is called a "shallow electron trap" because it is insufficient to hold it permanently. So Nevertheless, shallow electron trap sites are useful. For example, for high intensity exposure A large number of photoelectrons generated by the photoelectrons are efficiently transferred to the latent image formation site for a certain period of time. And then easily held in a shallow electron trap You can avoid dissipating.   In order for the dopant to be useful to form a shallow electron trap, it must simply be crystalline. More positive than the net valency of the displacing ion (s) in the lattice Further criteria beyond providing a net valence must be met. Do When a punt is incorporated into a silver halide crystal lattice, it contains silver halide valence electrons and conduction bands. Besides the critical energy level or orbit, new electronic energy A rugged level (orbit) is formed. Useful as electron trap with shallow dopant In order to be, these additional criteria must be satisfied: (1) Highest energy electron occupied orbit (HOMO; generally called "frontier orbit") Must be satisfied). For example, if the orbit is two electrons (highest Must hold two electrons instead of one if possible . (2) The lowest energy unoccupied orbit (LUMO) is a silver halide crystal lattice Energy level must be higher than conduction band . If conditions (1) and / or (2) are not satisfied, local dopant induction From the conduction band minimum energy Even with low energy, local dopan on crystal lattice (unfilled HOMO or LUMO) There is an orbit derived from G. and the photoelectrons are preferentially retained in this low energy site. More efficient transfer of photoelectrons to the latent image forming site is hindered.   Metal ions satisfying the criteria (1) and (2) are as follows: valence +2 Group 2 metal ion, valence +3 group 3 metal ion (however, satisfies the criterion (1)) Rare earth elements 58-71), a valence +2 group 12 metal ion (Hg⁺¹ (Excluding Hg, which is a strong desensitizer that seems to return to nature), with a valence of +3 Group 13 metal ion, valence +2 or +4 Group 14 metal ion and valence Group 15 metal ions that are +3 or +5. Metals that meet the criteria (1) and (2) Of the ions, it is preferable because it is practically convenient to incorporate as a dopant. The elements include the following 4, 5 and 6 period elements: lanthanum, zinc, cad Mium, gallium, indium, thallium, germanium, tin, lead and bismuth . A wrinkle that meets the criteria (1) and (2) used to form a shallow electron trap. Preferred metal ion dopants are zinc, cadmium, indium, lead and vinyl. It's Thomas. Specific examples of these types of shallow electron trap dopants are given above. DeWitt, Gilman et al., Atwell et al., Weyde et al. And EPO   0 590 674 and 0 563 946 (Murakima et al.). Have been.   Groups 8 and 9 that fill the frontier orbitals and thereby meet criterion (1) And Group 10 metal ions (hereinafter collectively referred to as "Group VIII metal ions") We also examined it. These are Group 8 metal ions of valence +2, valence +3 And a Group 10 metal ion having a valence of +4. These metals The ions, when incorporated as bare metal ion dopants, are effective shallow electron traps. It was found that no loop could be formed. This is because LUMO has a silver halide crystal lattice Lowest energy level due to lower energy level than conduction band .   However, these Group VIII metal ions as well as Ga⁺³And In⁺³ Can also form effective shallow electron traps when used as a dopant. You. The requirement that the frontier orbitals of metal ions be satisfied satisfies the criterion (1) I do. For satisfying criterion (2), the number of ligands forming a coordination complex should be small. One of them must be more electron withdrawing than the halide (ie Also has a higher electron withdrawing property. There must be).   One common method for evaluating electron withdrawing properties is Inorganic Che mystry: Principles of Structure and R activity, James E.W. Huhey, 1972, Harpe r and Row, New York and Absorption Spectra an d Chemical Bonding in Complexes, C.I. K. Jorgensen, 1962, Pergamon Press, London Obtained from the absorption spectra of metal ion complexes in the solutions mentioned in Refer to the spectrochemical series of As is clear from these documents, The order of the ligands in the photochemical series is as follows:     I^-<Br^-<S^-2  <SCN^-<Cl^-<NO_Three ^-<F^-<OH     <OX^-2  <H ₂ O  <NCS^-<CH_ThreeCN ^-<NH_Three<En <dipy     <Phen <NO₂ ^-<Phosph <<CN^-<CO Abbreviations used are as follows: ox = oxalate, dipy = dipi Lysine, phen = o-phenatroline and phosph = 4-methyl-2,6 , 7-Trioxa-1-phosphabicyclo [2.2.2] octane. In the spectrochemical series, the ligands are in electron-withdrawing order, and First (I^-) Ligand is the least electron-withdrawing, and the last (CO) ligand is the least. Also have a high electron withdrawing property. The underline indicates the binding site of the ligand to the polyvalent metal ion. ing. The ability of the ligand to increase the LUMO value of the dopant complex is bound to the metal Increase as the ligand atom changes from Cl to S, O, N, C in the order of You. Therefore, the ligandCN^-as well asCO is particularly preferred. Other preferred resources Gand is a thiocyanate (NCS^-), Selenocyanate (NCSe^-), Shea Nate (NCO^-), Terrocyanate (NCTe^-) And azide (N_Three ^-) Is .   Just as the spectrochemical series can be applied to the ligands of the coordination complex, Applicable to ON. The spectrochemical series of the following metal ions is Absorbtio n Spectra and Chemical Bonding, C.I. K. J Orgensen, 1962, reported on the pergamon press, London. It has been tell:     Mn⁺²  <Ni⁺²  <Co⁺²  <Fe ⁺²   <Cr⁺³     >> V⁺³  <Co ⁺³   <Mn⁺⁴  <Mo⁺³  <Rh ⁺³     >> Ru⁺³  <Pd ⁺⁴   <Ir ⁺³   <Pt ⁺⁴ The underlined metal ions satisfy the above-mentioned frontier orbit requirement (1). This All metals specifically intended for use in coordination complexes as dopants It does not contain ions, but the position of the remaining metals in the spectrochemical series is Ion position in the periodic table As the position increases from the 4th cycle to the 5th cycle and the 6th cycle, Metal Mn with the smallest electronegativity of ion position⁺²The most electronegative metal Pt⁺⁴Can be confirmed from the shift in the direction of. When the positive charge increases, the series The position also shifts in the same direction. That is, Os that is the sixth period ion⁺³Is the 5th cycle Most electronegative ion Pd⁺⁴More electronegative, but most charged in the sixth cycle Ion Pt which is negative⁺⁴Less electronegative than.   From the above description, Rh⁺³, Ru⁺³, Pd⁺⁴, Ir⁺³, Os⁺³And Pt⁺⁴Is clear The most electronegative metal ion that satisfies the crab frontier orbit requirement (1) And is therefore a particularly preferred metal ion.   In order to satisfy the LUMO requirement of the above criterion (2), the group VIII filled Freon The orbital polyvalent metal ion is incorporated into the ligand-containing coordination complex. Of these At least one, most preferably at least three, and optimally at least four, Is more electronegative than the logenide, and the remaining ligand (s) is halogen Compound ligand. Os⁺³When the isometal ion is itself very electronegative, Only a single large electronegative ligand, such as carbonyl, satisfies LUMO requirements It is required to be added. If the metal ions are themselves Fe⁺²Relatively electronegativity such as If low, choosing one in which all of the ligands are very electronegative is Required to satisfy UMO requirements. For example, Fe (II) (CN)₆Is Specifically preferred are shallow electron trapping dopants. In fact, cyano ligands A coordination complex containing six is generally a preferred type of shallow electron trap. This is a typical example of a dopant.   Ga⁺³And In⁺³Meets HOMO and LUMO requirements as bare metal ions Therefore, when incorporating into the coordination complex, Negativeness is useful for halogen ion to group VIII metal ion coordination complexes It can contain a range of ligands over some more electronegative ligands.   In the case of a ligand having an intermediate level of electronegativity with a group VIII metal ion, Certain metal coordination complexes meet LUMO requirements, thus providing a shallow electron trap Contains the right combination of metal and ligand electronegativity to fulfill all roles Can be easily determined. It uses electron paramagnetic resonance (EPR) spectroscopy. You can do that. This analytical technique is widely used as an analytical method , Electron Spin Resonance: A Comprehen live Treatise on Experiental Techni ques, 2nd edition, Charles P. Poole, Jr. (1983), J ohn Wiley & Sons, New York.   In a shallow electron trap, the photoelectrons are the conduction band energy of the silver halide crystal lattice. Produces an EPR signal very similar to that observed for photoelectrons at I will. EPR signals from shallowly captured electrons or conduction band electrons are electronic EPR signals It is called. An electronic EPR signal is characterized by a parameter generally called a g-factor. Be signed. A method for calculating the g-factor of an EPR signal is described in the above C.I. P. Po ole. G-factor of electronic EPR signal in silver halide crystal lattice The electron depends on the type of halogen ion (s) near the electron. That is, R. S. Eachus, M .; T. Olm, R.A. Janes and M.S. C. R. Sy mons, Physica Status Solidi (b), Vol. 152 ( 1989), p. 583-592, AgCl crystals. , The g factor of the electronic EPR signal is 1.88 ± 0.001 and The g-factor of the electronic EPR signal in AgBr is 1.49 ± 0.02.   The coordination complex dopant is the corresponding undoped in the test emulsion described below. If the magnitude of the electronic EPR signal is increased by at least 20% compared to the control emulsion Has been found useful in forming shallow electron traps in the practice of the present invention. You. Undoped control emulsions are disclosed in US Pat. No. 4,937,180 (Marchett). i)) precipitated but followed by sensitization as described for Control 1A. This is an AgBr octahedral emulsion having an edge length of 0.45 ± 0.05 μm. test The emulsion contains Marc at a concentration of the metal coordination complex intended for use in the emulsion of the present invention. Os (CN in Example IB of Hetti et al.₆)^Four-Use instead of.   After precipitation, the test and control emulsions were each centrifuged first, and the supernatant was removed. The supernatant is replaced with the same volume of warm distilled water, and the emulsion is resuspended. Prepare for PR signal measurement. This operation was repeated three times, and after the final centrifugation step, the resultant was obtained. Air dry the powder. These operations are performed under safe light conditions.   EPR test, three samples of each emulsion cooled to 20, 40 and 60 ° K respectively And exposing each sample to filtered light from a 200 WHg lamp having a wavelength of 365 nm. This is done by measuring the EPR electronic signal during. If the selected observation temperature In either case, the intensity of the electronic EPR signal is higher than that of the undoped control emulsion. Significant increase in agent sample (ie measurable increase above signal noise) ), This dopant is a shallow electron trap.   As a specific example of the test performed as described above, a commonly used shallow electron Trap dopant Fe (CN)₆ ^Four-During the precipitation of one mole of silver as described above. 50x10 per le^-6With dopant Electronic EPR signal strength when added, undoped control emulsion when tested at 20 ° K 8 times increase.   Hexacoordination complexes are the preferred coordination complexes for use in the practice of the present invention. This These complexes have silver ions and six adjacent halogen ions in the crystal lattice. It contains a replacing metal ion and six ligands. One or two of the coordination sites Be occupied by neutral ligands such as carbonyl, carbonyl, aco or amine ligands However, the rest of the ligand can efficiently incorporate the coordination complex into the crystal lattice structure. Must be an anion to facilitate. Include in Protrusion An example of a hexacoordination complex specifically intended for use in U.S. Pat. No. 5,037,7 32 (McDugle et al.), U.S. Pat. Nos. 4,937,180 and 5,264. , 336 and 5,268,264 (Marchetti et al.), U.S. Pat. No. 4,945,035 (Keevert, etc.) and Japanese Patent Application No. 2-249588 (Mura) Etc.). Useful neutral and anionic organic ligas for hexacoordination complexes. Are disclosed in US Pat. No. 5,360,712 (Olm et al.). R. S. Eachus, R .; E. FIG. Graves and M.E. T. Olm, J. Chem. Phys. , 69, 4580-7 (1978) and Physica. Status Solidi A, Vol. 57, pp. 429-37 (1980). As shown, careful scientific research has shown that Group VIII hexahalo coordination complexes It was revealed that the body forms a deep (desensitized) electron trap.   In a specific preferred embodiment, a hexacoordination complex satisfying the following formula as a dopant Is intended to use: (V)                 [ML₆]ⁿ (In the formula, M is a filled frontier orbital polyvalent metal ion (preferably Fe⁺², Ru⁺² Or Os⁺²) Is;   L₆Represents six independently selectable coordination complex ligands, with the proviso that , At least four of the ligands are anionic ligands, and at least One (preferably at least 3 and optimally at least 4) is any halo It is more electronegative than the genide ligand (ie, the most electronegative halide ion). It is more electron withdrawing than the fluoride ion which is on); and   n is a negative integer whose absolute value is less than 5 (preferably -2, -3 or -4). You.   The following are specific examples of dopants that can provide a shallow electron trap:     SET-1 [Fe (CN)₆]^-Four     SET-2 [Ru (CN)₆]^-Four     SET-3 [Os (CN)₆]^-Four     SET-4 [Rh (CN)₆]^-3     SET-5 [Ir (CN)₆]^-3     SET-6 [Fe (pyrazine) (CN)_Five]^-Four     SET-7 [RuCl (CN)_Five]^-Four     SET-8 [OsBr (CN)_Five]^-Four     SET-9 [RhF (CN)_Five]^-3     SET-10 [IrBr (CN)_Five]^-3     SET-11 [FeCO (CN)_Five]^-3     SET-12 [RuF₂(CN)_Four]^-Four     SET-13 [OsCl₂(CN)_Four]^-Four     SET-14 [RhI₂(CN)_Four]^-3     SET-15 [IrBr₂(CN)_Four]^-3     SET-16 [Ru (CN)_Five(OCN)]^-Four     SET-17 [Ru (CN)_Five(N_Three)]^-Four     SET-18 [Os (CN)_Five(SCN)]^-Four     SET-19 [Rh (CN)_Five(SeCN)]^-3     SET-20 [Ir (CN)_Five(HOH)]^-2     SET-21 [Fe (CN)_ThreeCl_Three]^-3     SET-22 [Ru (CO)₂(CN)_Four]^-1     SET-23 [Os (CN) Cl_Five]^-Four     SET-24 [Co (CN)₆]^-3     SET-25 [Ir (CN)_Four(Oxalate)]^-3     SET-26 [In (NCS)₆]^-3     SET-27 [Ga (NCS)₆]^-3   The total concentration of SET dopant is 1 × 10^-6~ 5 × 10^-FourMol / Ag mol range In other words, 1 to 500 mppm of silver (molar pa) It is effective in the range of rts per million. Preferred Total SET Do The punt concentration is 10 to 300 mppm of silver (1 x 10^-Five~ 3 x 10^-FourMol / Ag Mol).   The SET dopant is too close to the surface of the particles, as shown in the data below. Then sub-optimal results are obtained. Therefore, the surface of the SET dopant 100 mpp of silver forming concentration 5% outside of grain structure (last deposited) It is intended to be limited to less than m. Preferably outside the grain structure (finally deposited 30%) has a SET dopant concentration of less than 100 mppm. Tabular grain A teaching that limits the concentration of SET dopants on the surface of the child is the surface area of the particles. Of course, to completely eliminate the SET dopant from That is, flat While the final surface portion of the plate-like particles is formed, It is specifically contemplated and preferred to stop the addition of SET dopant. SE The T-dopant may be limited to a narrow band or incorporated within the grain in any desired manner. You may make it cloth.   The SET dopant can be effectively used in the emulsion of the present invention which is not spectrally sensitized, Quite unexpectedly, the SET dopant was one or more cyanine spectral sensitizing dyes. The oxidation potential (Eox) shows a positive value less than +0.87 volts and the dye With redox potential difference (Eox-Ered) of less than 2.10 volts It has been found that when used together, the photographic speed increases relatively significantly. Minute To realize the advantages of the present invention when used in combination with photosensitizing dyes, a kind of Only the cyanine dye needs to satisfy the above Eox and Eox-Ered. It is said.   The redox potentials of cyanine dyes have been extensively studied and therefore these Specific cyanine dyes satisfying the preferred requirements Eox and Eox-Ered of It can be sufficiently selected by those skilled in the art. The redox potential of the cyanine dye is Photogr apic Science and Engineering, Volume 18, 1 974, pages 49-53 (Sturmer et al.), 175-185 (Leu bner) and 475-485 (Gilman) and Gilman, 1st. Volume 9, 1975, p. 333, extensively explained. Redox potential is , R.A. J. Cox, Photographic Sensitivity, Ac as described in chapter 15 of the Adless Press, 1973. Can be measured. The properties of the spectral sensitizing dyes, together with a wide range of examples, are described above in ch Disclosure, item 36544, section V.n. "Spec tralization and desensitization on, A. Sensitizing d yes ”. Not only Section V but also Hamer The C yanine Dyes and Related Compounds, Jh on Wiley & Sons, 1964, simple (monomethine) cyani , Carbocyanine (trimethine cyanine), dicarbocyanine (pentamethine Cyanine), tricarbocyanine (heptamethine cyanine) and complex (polynuclear) Various forms of cyanine dyes have been shown, including cyanines.   I. H. Leubner, Photogr. Sci. Eng. 22: 271 ( 1978), as the Eox-Ered decreased, It was shown that the wavelength of peak absorption becomes longer. This is shown by the relation: (VI)           Eox-Ered = 1.145 (hv-2.225) +1.858 (Where h is Planck's constant, v is the frequency of light (the reciprocal of the wavelength)).   Leubner can be further calculated by the following relational expression in terms of peak absorption in solution ( nmSol) is associated with J-aggregation peak absorption (nmJ): (VII)           nmJ = 1.44 (nmSol-500) +555 That is, Eox-Ered 1.10 volts has a solution peak absorption (nmSol) 79. 3 nm or, if aggregated, a J-aggregation peak absorption (nmJ) of 977 nm. Represented by an anine dye. If Eox-Ered is 1.20 volts, this is equivalent NmSol and nmJ are 751 nm and 917 nm, respectively. Eox -When Ered is 1.40 Volts, the corresponding nmSol and nmJ are respectively Are 679 nm and 813 nm. For the majority of practical applications , The cyanine spectral sensitizing dye used has an Eox-Ered value of at least 1.10. It has low Eox-Ered in most applications using cyanine dyes. At least 1.20 volts, most commonly at least 1.40 volts Is intended.   Below is shown a positive value where the oxidation potential is less than +0.87 volts, Specific examples of preferred spectral sensitizing dyes for use in the emulsions of the present invention are:     SS-1: Anhydro-5,5'-dichloro-9-ethyl-3,3'-bis (3-Sulfopropyl) thiacarbocyanine hydroxide, triethylammoni Umm salt             (Eox = + 0.85V, Ered = −1.16V,               Eox-Ered = 2.01V)     SS-2: Anhydro-9-ethyl-5,5'-dimethyl-3,3'-bis (3-Sulfopropyl) thiacarbocyanine hydroxide, triethylammoni Umm salt             (Eox = + 0.76V, Ered = -1.22V,               Eox-Ered = 1.98V)     SS-3: Anhydro-5,5'-dichloro-3,9-diethyl-3 '-( 3-sulfobutyl) thiacarbocyanine hydroxide             (Eox = + 0.86V, Ered = −1.15V               Eox-Ered = 2.01V)     SS-4: Anhydro-5,5'-dimethoxy-9-methyl-3,3'-bi Sus (3-hydroxypropyl) thiacarbocyanine hydroxide, bromide salt             (Eox = + 0.75V, Ered = −1.15V,               Eox-Ered = 1.90V)     SS-5: Anhydro-3,9-diethyl-5,5'-dimethoxy-3'- (3-Sulfopropyl) thiacarbocyanine hydroxide             (Eox = + 0.73V, Ered = -1.20V,               Eox-Ered = 1.93V)     SS-6: Anhydro-5,5'-dimethoxy-9-methyl-3,3'-bi Sus (3-sulfopropyl) thiacarbocyanine hydroxide, sodium salt             (Eox = + 0.72V, Ered = -1.22V,               Eox-Ered = 1.94V)     SS-7: Anhydro-9-ethyl-5 ', 6'-dimethoxy-5-phenyl Le-3 '-(3-sulfobutyl) -3- (3-sulfopropyl) oxathiacal Bocyanine hydroxide             (Eox = + 0.69V, Ered = −1.34V,               Eox-Ered = 2.03V)     SS-8: Anhydro-5,6-dichloro-1-ethyl-3- (3-sulfo Butyl) -3 '-(3-sulfopropyl) -4', 5'-benzo-benzimidazole Zorothia carbocyanine hydroxide             (Eox = + 0.68V, Ered = −1.34V,               Eox-Ered = 2.02V)     SS-9: Anhydro-9-ethyl-5,6-dimethoxy-5'-phenyl -3,3'-bis (3-sulfopropyl) thiacarbocyanine hydroxide, Lium salt             (Eox = + 0.64V, Ered = −1.24V,               Eox-Ered = 1.88V)     SS-10: Anhydro-9-ethyl-3,3'-bis (3-sulfopropyi) ) -4,5; 4 ', 5'-dibenzothiacarbocyanine hydroxide, Natri Umm salt             (Eox = + 0.60V, Ered = −1.33V,               Eox-Ered = 1.98V)   In addition to the SET dopant, the emulsions of this invention optionally contain other dopants. be able to. Other conventional dopants are Research Discs described above. Loss, Item 36544, "I. Emulsion grains and ther preparation, D.I. Grain modify ing conditions and adjustment, paragraph ( It is described in 3).   For example, selenium as a dopant (hereinafter, also referred to as “Se dopant”) It has been found that when incorporated, the selenium sensitization of the emulsion is enhanced. The selenium dopant is It is of the type disclosed in US Pat. No. 5,166,045 (Wu). During the deposition of the portion of the grain where the selenium dopant is located, the selenium donor is Exists. Selenium may be compounded in the elemental form (ie Se °), organically or May be incorporated in a divalent form in an inorganic compound. Specific preferred inorganic compounds The object can take the following forms: (VIII)                   M-Se-L (In the formula, M is a monovalent metal such as an alkali metal,   L is halogen or pseudohalogen). The halogen can be selected from fluoride, chloride and bromide. "Pseudo halogen ”In the art is reactively similar to halogens, and at least Used to indicate a ligand whose negativeness is the same as halogenated. Preferably, L completes the selenocyanate or isoselenocyanate component with Se .   In the preferred organic selenium source compound, -Se- or Se = bond pattern is present The selenium atom is typically attached to carbon, nitrogen or phosphorus. C Carbon, nitrogen or phosphorus bonds not satisfied by len are hydrogen or carbon atoms of about 10 or more. Satisfied with organic components such as substituted or unsubstituted alkyl or aryl components below Can be done. Lower alkyl (<6 carbons, optimally <4 carbons) is preferred However, preferred aryl components are charcoal such as phenyl lower alkyl substituted phenyl components. It is a prime number 6-10.   As specific examples of the selenium dopant source material to be contained during precipitation, Examples include:   Se-1: Colloidal selenium   Se-2: Potassium selenocyanate   Se-3: selenoacetone   Se-4: selenoacetophenone   Se-5: Serenourea   Se-6: Tetramethylselenourea   Se-7: N- (β-carboxyethyl) -N ', N'-dimethylselenourea   Se-8: N, N-Dimethylselenourea   Se-9: selenoacetamide   Se-10: Diethyl selenide   Se-11: diphenyl selenide   Se-12: Bis (2,4,6-trimethylphenyl) selenide   Se-13: Triphenylphosphine selenide   Se-14: Tri-p-tolyl selenophosphate   Se-15: tri-n-butylselenophosphate   Se-16: 2-selenopropionic acid   Se-17: 3-selenobutyric acid   Se-18: Methyl-3-selenobutyrate   Se-19: Allyl isoselenocyanate   Se-20: N, N'-dioctylselenourea   The preferred selenium dopant concentration is 1 × 10^-6~ 7 × 10^-FiveMol / Ag mol In other words, the range is 1 to 70 mppm. The selenium concentration was Even when the Se dopant is introduced during the precipitation of only a portion of the grains, the total silver-based It is quasi. The Se dopant is in any convenient portion or grain shape of the grain formation. It can be introduced during the whole process, but is preferably introduced before the conversion of halide. It is preferred to obtain a distributed edge and corner iodide.   In order to maximize the performance of SET and Se dopants, these dopants are It is preferred to incorporate into separate portions of the tabular grains. Preferably less total silver With 10 mol% of the completion of the introduction of one of the dopants and the introduction of the remaining dopant. Precipitate between start. The dopants may be introduced in any order, but the SET It is preferred that the introduction of the dopant be completed before the introduction of the Se dopant.   Iridium dopant capable of reducing reciprocity law failure in low illumination Are preferably incorporated into the tabular grains of the emulsions of this invention. Reduced low-light reciprocity failure Specific examples of iridium dopants that can be used to do this are described in US Pat. No. 4,449. , 751 (Kim) and US Pat. No. 5,164,292 (Johnson). It is described in. Irrigation used to reduce failure or for other purposes For a more general review of indium dopants, see B. H. Carroll, Iridi um Sensitization: A Literature Review , Photographic Science and Engineering g, Vol. 24, No. 6, November and December 1980, pp. 265-267. Have been. It also contains iridium dopants intended to reduce failure. An even more general overview is Research Disclosure, Eye. System 36544, Section I. "Emulsion grains and ther preparation, D.I. Grain modifying conditions and adjustments, paragraph (3) and And (4). Known to reduce low-light reciprocity failure Any of the iridium dopants described above are useful for this purpose in the practice of the present invention. Any amount known to be used can be used.   In a specifically preferred embodiment, the iridium dopant is hexadecimal which satisfies the following formula: Incorporate into the crystal lattice structure of the particles in the form of coordination complexes: (IX)               [Ir⁺³X_FiveL ’]^m (In the formula, X is a halide ligand,   L'is any bridging ligand, and   m is -2 or -3).   When adding iridium during precipitation, ammonium or alkali A convenient counterion, such as a lithium metal, is associated with the hexacoordination complex, but Only the on part is actually incorporated into the crystal lattice structure. Also, for example, US Patent No. 4,902,611 (Leubner et al.). When present, iridium can be in the +4 valence state. However , +4 iridium returns to the +3 valence state when incorporated. Chloride and bromide Are the preferred halide ligands. The cross-linking ligand L'also halogenated The ligand may also be a compound ligand, and is also disclosed in U.S. Pat. No. 4,933,272, 981,781 and 5,037,732 (McDugle et al.), US Pat. 4,937,180 (Marchetti et al.), U.S. Pat. No. 4,945,03. No. 5 (Keevert et al.) And US Pat. No. 5,360,712 (Olm et al.) Of any of the various individual ligand forms disclosed in It can also take the usual forms. Sources other than chloride and bromide ligands H is a typical ligand₂O, F^-, NCS^-, SCN^-, CN^-, NCO^-, I^-, N_Three ^-, NO_Three ^-, NO₂ ^-And substituted or unsubstituted pyrazine, pyrimidine, thiazole , Oxazole, pyridine, acetonitrile and pyridazine ligands Gand and so on.   The iridium dopant is preferably at least 2 of the silver forming tabular grains. 9% of silver after 0 (most preferably 60)% precipitation and forming tabular grains 0 (most preferably 80)% is introduced before precipitation. Of iridium dopant The ideal position is formed just before the precipitation of the tabular grain surface that excludes iridium. It is in the obi. Preferably at least 20% of the total silver (optimally at least 60%) is precipitated before introducing iridium.   The preferred concentration of iridium dopant is about 800 (based on total silver). Most preferably 140) mppb (molar parts per bill) ion) or less, or in other words, 8x10^-7Mol / Ag mol or less It is. The minimum effective iridium concentration is reported to be 2.8 mppb, Concentrations of at least about 15 mppb are more convenient to use.   The unwanted interaction between SET and iridium dopants is maximized. In order to reduce the size, the introduction of SET dopant and the start of iridium doping It is preferable to deposit an intervening zone between the two. The intervening zone is preferably low in total silver 10%, optimally at least 20% of total silver. Selenium and iridium Dopants do not exhibit unwanted interactions, so they can be introduced at exactly the same time. Good, may be introduced completely sequentially, or may be introduced in any desired manner between them. Good.   In addition to the features noted above, the tabular grain emulsions of this invention can be any convenient conventional emulsion. You may take the form of. Conventional emulsion formulations specifically intended to be compatible with this invention. Among the manufacturing methods, Research Disclosure, Vol. 365, 199. September 4th, item 36544, I.S. "Emulsion grains an d tire preparation "," A. Grain halide   composition ", paragraph (5);" C. Precipitat ion procedures "; and" D. Grain modifying   conditions and adjustments ", paragraph (1) And (6).   Subsequent to precipitation, the emulsion of the present invention was processed into the above-described Research Discloses. ure, item 36544, "I. Emulsion grains and   ther preparation "," E. Blends, layers and performance c "". Vehicles, vehicle exte nders, vehicle-like addenda and vehic "le related adda"; "III. Emulsion wa "". Chemical Sensitization ”; and And "V. Spectral Sensitization and Desen" location, A.A. Spectral sensing dy es "and can be prepared for photographic use.   The emulsions or photographic elements may further include Research Disclosure as described above. e, Item 36544: "VII.Antifoggants and st. abilizers ";" VIII. Absorbing and scatt ering materials ";" IX. Coating physica l property modifying addenda ";" X. Dye   "image formers and modifiers"; "XI. La "Yers and layer arrangements"; "XII. Fe atures applicable only to color nega “Tive”; “XIII. Features applicable only   to color positive ";" XIV. Scan facili tatting features "; and" XV. Shown in Supports ” One or more of the following can be included.   The exposure and processing of photographic elements incorporating the emulsions of this invention is carried out as described above in Research.   Disclosure, Item 36544, "XVI.Exposure" ; XVIII. Chemical d development systems ";" XIX. Development "; And" XX. Desilvering, washing, rinsin g and stabiliZing "in a convenient conventional form. You may. Example   The present invention may be better understood by reference to the following specific examples. . Example 1   The purpose of this example is to place the iodide within the tabular grains to produce It is to show that improvement in photographic speed can be realized regardless of the addition of the toner. Emulsion A   This emulsion is generally similar to the emulsions of the invention but is a feature of the invention. The difference is that there is no unusual iodide placement.   In a 4 liter reaction vessel, an aqueous gelatin solution (1 liter of water, low alkali treated Thionine gelatin 0.56 g, 4N nitric acid solution 3.5 ml, sodium bromide 1.1 2 g, pAg 9.38) and 14. based on the total weight of silver used for nucleation. 4% by weight of PLURONIC-31R1 ™ (formula: (X) (Wherein x = 7, y = 25 and y, = 25) Add while maintaining at 45 ° C., and add silver nitrate aqueous solution (containing 0.48 g of silver nitrate) 11.13. ml and sodium bromide aqueous solution (containing 0.29 g of sodium bromide) 11.13 m l and constant over 1 minute Simultaneous addition at rate. The mixture is held and stirred for 1 minute, during which time the sodium bromide When holding 14 ml of an aqueous solution of um (containing 1.44 g of sodium bromide) for 50 seconds Added in points. Then, after holding for 1 minute, the temperature of the mixture was raised to 60 ° C over 9 minutes. Raised. Next, an ammonium sulfate aqueous solution (containing 1.68 g of ammonium sulfate) ) 16.7 ml was added and the pH of the mixture was adjusted to aqueous sodium hydroxide (1N). It was adjusted to 9.5. The mixture thus prepared was stirred for 9 minutes. next, Add 83 ml of gelatin aqueous solution (containing 16.7 g of alkali-treated gelatin) and mix. After stirring the mixture for 1 minute, the pH was adjusted to 5.85 using a nitric acid aqueous solution (1N). Was. The mixture was stirred for 1 minute. Then, a silver nitrate aqueous solution (silver nitrate 1.27 g 30 ml) and an aqueous solution of sodium bromide (containing 0.66 g of sodium bromide) 3 2 ml were added simultaneously over 15 minutes. Next, an aqueous solution of silver nitrate (silver nitrate 13 . 3 ml) and 49 ml of aqueous sodium bromide solution (containing 8.68 g of sodium bromide). Yes) 48.2 ml and an initial velocity of 0.67 ml / min and 0.72 ml / min, respectively. Min, 24.5 minutes linearly accelerated and co-added. Next, an aqueous solution of silver nitrate (glass 468 ml of silver acid salt (containing 191 g) and an aqueous solution of sodium bromide (sodium bromide 11 (Including 9.4 g) 464 ml and initial speeds of 1.67 ml / min and 1.7, respectively. From 0 ml / min, simultaneous addition was performed with linear acceleration for 82.4 minutes. Then do not stir For 1 minute.   Next, 80 ml of an aqueous silver nitrate solution (containing 32.6 g of silver nitrate) and a halide aqueous solution Liquid (containing 13.2 g of sodium bromide and 10.4 g of potassium iodide) 69.6 m and 1 were added simultaneously at a constant rate over 9.6 minutes. Next, an aqueous solution of silver nitrate (glass 141 ml of silver oxide (containing 57.5 g) and an aqueous solution of sodium bromide (sodium bromide 3 (Including 8.0 g) and 147.6 ml are simultaneously added at a constant rate over 16.9 minutes. did. The silver iodobromide emulsion thus obtained contains 3.6 mol% iodide. Was. The emulsion was then washed. The grain characteristics of this emulsion are shown in Table II. Emulsion B   The emulsion has the speed advantage due to the iodide configuration which is a requirement of the invention.   Up to the step of introducing iodide, the method used for preparing Emulsion A was used. There Precipitation was performed as follows:   Next, potassium iodide aqueous solution (containing 10.45 g of potassium iodide) 16.6 m 1 was added at a constant flow rate over 3 minutes. This solution is best mixed It was discharged to the position of the reaction vessel. After holding for 10 minutes, an aqueous silver nitrate solution (silver nitrate 220.8 ml (containing 90.1 g) was added at a constant flow rate over 26.5 minutes. Then, 6.5 minutes after the start of addition of silver nitrate, an aqueous solution of sodium bromide (sodium bromide 4 164.2 ml (containing 2.2 g) was added at a constant flow rate over 20.0 minutes. This The silver iodobromide emulsion thus obtained contained 3.6 mol% of iodide. . The emulsion was then washed. The grain characteristics of this emulsion are shown in Table II. Photo comparison   The emulsions listed in Table II were tested for optimum sulfur and gold sensitization and the last sensitizing dye present. As anhydro-5-chloro-9-ethyl-5'- Phenyl-3 '-(3-sulfobutyl) -3- (3-sulfopropyl) -oxa Carbocyanine hydroxide, sodium salt (Eox = 1.05 Volt, Ere d = -1.31 volts, Eox-Ered = 2.36 volts) (SS-11) Anhydro-3,9-diethyl-3 '-[N- (methylsulfonyl) carbamoy Lumethyl] -5-phenylbenzothiazolo-oxacarbocyanine hydroxide , Inner salt (Eox = 0.80 volt, Erde = -1.30 volt, Eox− Combined with Ered = 2.10 Volt) (SS-12) at a weight ratio of 8.2: 1. I used it as a negative blue sensitizer.   Single layer coatings on transparent film supports include cyan dye forming couplers (CC-1 ) (Coating amount: 1.6 mg / dm²) And a silver coating (coating amount 8.1 mg / dm²) And Was. (CC-1)   Remarkably transmits each coating film sample with a graduated density test object and wavelengths longer than 480 nm With a tungsten light source through a Wratten 9 ™ filter Glowed. The treatment is Eastman Flexicolor (trademark) color negative treatment. Conducted using physicochemicals and methods.   A sensitometric sensitivity comparison is shown in Table III. The sensitivity is 0. Measurements were made at 15 high optimum concentrations. Relative sensitivity of emulsion A is 100 Is 0.01 log E (where E is the exposure dose (unit: lux. Second) represents).   As a reference, the relative sensitivity is increased by 30 (0.30 log E) in the photograph. Then, the exposure amount can be reduced by one stop. Therefore, with the emulsion of the present invention It is clear that a person who reduces the exposure amount can reduce the exposure amount by half. Morphological comparison   Microscopic examination of both Emulsion A and Emulsion B grains revealed different tabular grain structures. Found to have a structure.   The iodide concentrations of a representative sample of tabular grains were measured across their major faces (edge- Edge-to-edge or corner-to-corner) (line EE in "Brief description of drawings") And C-C). Analytical electron microscopy (AEM) was used . The major surface of each tabular grain investigated was addressed at successive points and at each addressed point The average iodide concentration for the total tabular grain thickness was read and plotted.   Figure 2 shows the edge-edge for a representative tabular grain from Emulsion A. Plot E2 and corner-corner plot C2 are shown. On both plots And it can be seen that the highest iodide concentrations are found around the tabular grains. Of particles Between the iodide concentration at the corner and the iodide concentration around the corner spacing There is no noticeable difference. All of the tabular grains tested and collected from Emulsion A were prepared from these emulsions. Edge and corner iodide distribution characteristics.   A total of 60 tabular grains collected from Emulsion B were investigated. 17 of these Are edge-to-edge and similar to the tabular grains of Emulsion A. And corner-corner iodide distribution. However, of the tabular grains 43 of them showed a unique and surprising iodide distribution. 43 with unique structure Edge-edge iodide distribution E for a representative tabular grain of a single tabular grain 1 and the corner-corner iodide distribution C1 is shown in FIG. Notable , The highest iodide concentration is at the edge around the tabular grain in the edge-edge plot E1. To be observed. On the other hand, the corner-corner plot C1 shows the iodide around the tabular grains. The compound content does not change significantly. Clearly, in these unique tabular grains The highest iodide concentrations are located at the edges of the tabular grains, but The iodide concentration in the tunner is dependent on any observed along the perimeter edges of the tabular grains. Clearly significantly lower than the location. Example 2   In addition to the arrangement of iodide, which is a requirement of the present invention shown in Example 1, , SET dopant and positive value less than + 0.87V It is shown that the sensitivity is further increased by selecting the spectral sensitizing dye showing. Emulsion C   This emulsion satisfies the iodide configuration which is a requirement of the present invention, but does not contain SET. I didn't.   In a container equipped with a stirrer, 3.4 g of oxidized bone gelatin and 6.7 g of sodium bromide And 0.5 g of the surfactant Pluronic 31R1 ™ (see formula X above) And 6 liters of water containing sufficient amount of nitric acid to bring the pH to 1.85 at 45 ° C. Was put. Aqueous silver nitrate solution (containing 2.88 g of silver nitrate while maintaining the temperature at 45 ° C) ) 68 ml and sodium bromide aqueous solution (containing 1.75 g of sodium bromide) 68 ml And were added simultaneously at a constant rate over 1 minute. Hold mixture for 1 minute Hold and stir, during which sodium bromide aqueous solution (containing 8.64 g of sodium bromide) ) 84 ml was added. Then the temperature of the mixture was raised to 60 ° C over 9 minutes. I let you. Next, an ammonium sulfate aqueous solution (containing 10 g of ammonium sulfate) 100 m 1 was added and the pH of the mixture was adjusted to 9.5 with sodium hydroxide. This The mixture thus prepared was stirred for 9 minutes. Gelatin solution (oxidized bone gelatin 500 ml (containing 100 g) is added, the mixture is stirred for 1 minute, and then pH is adjusted with nitric acid. Was adjusted to 5.85. The mixture was stirred for 1 minute. Then, the silver nitrate aqueous solution (glass 180 ml of silver oxide (containing 7.65 g) and an aqueous solution of sodium bromide (sodium bromide 3. 192 ml (containing 96 g) were simultaneously added over 15 minutes. Next, silver nitrate water 294 ml of a solution (containing 79.8 g of silver nitrate) and an aqueous solution of sodium bromide (Natri bromide) (Containing 52 g of um) 288 ml and an initial speed of 4 ml / min and 4.3 ml, respectively. / Min, linearly accelerated for 24.5 minutes and added simultaneously. Next, an aqueous solution of silver nitrate ( 2802 ml of silver nitrate 1146) and sodium bromide aqueous solution (sodium bromide 7 1784 g (containing 16.9 g) and 2784 ml, respectively, at initial rates of 10 ml / min and 10. From 2 ml / min, simultaneous addition was performed with linear acceleration for 82.4 minutes. Then stir While holding for 1 minute.   Next, 200 ml of an aqueous potassium iodide solution (containing 62.4 g of potassium iodide) was added. It was added at a constant flow rate over 2 minutes. This solution provides the best mixing in the reaction vessel. It was discharged to the position where After holding for 10 minutes, an aqueous silver nitrate solution (silver nitrate 54 0.625 g) (1325 ml) was added at a constant flow rate over 26.5 minutes. next 6.5 minutes after the start of addition of silver nitrate, an aqueous solution of silver bromide (containing 253.6 g of sodium bromide) was prepared. Yes) 985 ml was added at a constant rate over 20.0 minutes.   The silver halide emulsion thus obtained had an iodide content of 3. It was 6 mol%. The grain characteristics of this emulsion are shown in Table IV. Emulsion D   This emulsion was prepared in the same manner as Emulsion C except that a SET dopant was further added. did.   Prior to adding the potassium iodide solution, potassium hexacyanoruthenate. 22g (5.1 × 10 based on total silver)^-FiveMol / mol silver) containing aqueous solution to the mixture Was added.   The grain characteristics of this emulsion are shown in Table IV. Photo comparison   The emulsions listed in Table IV were optimized for sulfur and gold sensitization as well as the last sensitizing dye present. As a red sensitizer using SS-1 and SS-2 in combination at a molar ratio of 9: 1 did. Single layer coatings on transparent film supports include cyan dye forming couplers (CC -1) (Coating amount: 9.69 mg / dm²) And a silver coating (coating amount 10.76 mg / dm² ) And were used.   Remarkably transmits each coating film sample with a density test object with a scale and wavelengths longer than 560 nm A tungsten light source through a Wratten23A ™ filter Exposed. The process is performed by Eastman Flexicolor (trademark) color Moth treatment chemicals and methods were used.   A sensitometric sensitivity comparison is shown in Table V. The sensitivity is the same as in Example 1. It measured similarly. Example 3   This example shows the effect of changing the level of SET dopants and the configuration.   Varying the level and configuration of potassium hexacyanoruthenate dopant All emulsions were prepared and evaluated in the same manner as in Example 2 except for the above.   The significantly changed parameters and the resulting photographic speeds are summarized in Table VI.   Dopant distribution depends on the reaction vessel at the start and end of dopant introduction. Shows the dopant introduction interval based on the% of total silver present in.   From Table VI, with SET dopant, all concentrations and all dopant distributions It is clear that the sensitivity was increased. However, closer to the particle surface Emulsion L with a higher concentration of SET dopant was more effective than the rest of the doped emulsion. The increase in sensitivity was low. This means that the SET dopant concentration is It shows that you have to be limited to where you touch. Introducing dopant The highest sensitivity was observed when at least 30% of the total silver was subsequently introduced. Example 4   The purpose of this example is to detect the spectral sensitization of the blue and green regions of the spectrum, It is to show that the sensitivity of the emulsion is increased. Emulsion M   This emulsion is prepared for comparison. Emulsions of the invention described below Unlike, it does not contain a SET dopant.   In a container equipped with a stirrer, 6.8 g of oxidized bone gelatin and 6.7 g of sodium bromide And a surfactant PLURONIC 31R1 ™ (see formula VIII above) 2 6 liters of water containing g and nitric acid in an amount sufficient to bring the pH to 1.85 at 45 ° C. I put Le. While maintaining the temperature at 45 ° C, an aqueous solution of silver nitrate (containing 3.60 g of silver nitrate) was used. Yes) 42.4 ml and sodium bromide aqueous solution (containing 2.29 g of sodium bromide) 4 2.7 ml was added simultaneously at a constant rate over 1 minute. Hold mixture for 1 minute -Stirring, during which, aqueous sodium bromide solution (containing 8.82 g of sodium bromide) 86 ml was added. Then the temperature of the mixture was raised to 60 ° C over 9 minutes. Was. Next, an ammonium sulfate aqueous solution (containing 10.2 g of ammonium sulfate) 101 ml was added and the pH of the mixture was adjusted to 9.5 with sodium hydroxide. this The mixture thus prepared was stirred for 9 minutes. Gelatin solution (oxidized bone gelatin 1594 ml) was added, the mixture was stirred for 1 minute and then with nitric acid. The pH was adjusted to 5.85. The mixture was stirred for 1 minute. After that, silver nitrate aqueous solution 151.4 ml (containing 12.86 g of silver nitrate) and an aqueous solution of sodium bromide (sodium bromide) 256 ml (containing 13.7 g of lithium) were simultaneously added over 15 minutes. next , 936.2 ml of an aqueous solution of silver nitrate (containing 79.54 g of silver nitrate) and aqueous sodium bromide 1058 ml of a solution (containing 56.6 g of sodium bromide) and an initial rate of 1 Linear acceleration from 1.51 ml / min and 12.84 ml / min for subsequent 32 min And added simultaneously. Next, 2834 ml of silver nitrate aqueous solution (containing 1156 g of silver nitrate) And 2864 ml of an aqueous sodium bromide solution (containing 736.8 g of sodium bromide) , From initial rates of 10.1 ml / min and 9.66 ml / min, respectively, followed by 82 . It accelerated linearly for 4 minutes and added simultaneously.   Next, an aqueous potassium selenocyanate solution (0.305 g of potassium selenocyanate 265 ml) was added over 2 minutes.   Next, potassium iodide aqueous solution (containing 65.5 g of potassium iodide) 143.5 m 1 was added at a constant flow rate over 2 minutes. This solution is best mixed in a reaction vessel It was discharged to a position where it would be broken. After holding for 10 minutes, an aqueous silver nitrate solution (silver nitrate 545.0 g) (1337 ml) was added at a constant flow rate over 26.5 minutes. Next, 9.0 minutes after the start of addition of silver nitrate, an aqueous sodium bromide solution (sodium bromide 2 850 ml (containing 18.7 g) was added at a constant rate over 17.5 minutes. Get The obtained silver halide emulsion had an iodide content of 3.7 mol%. Then wash the emulsion Clean   The grain characteristics of this emulsion are shown in Table VII. Emulsion N   The emulsion is an emulsion according to the invention containing a SET dopant.   An emulsion was prepared similar to Emulsion M, except for the following: potassium selenocyanate. Oxygen solution was omitted, and potassium hexacyanoruthenate 0.22 g (based on total silver) 61 ml of an aqueous solution containing 50 mppm) is added to the mixture with 66% of total silver. Added during time corresponding to ~ 68% addition.   The grain characteristics of this emulsion are shown in Table VII. Photo comparison   The emulsions listed in Table VII were optimally spectrally and chemically sensitized. Chemical sensitizers are It was a sulfur and gold sensitizer. Spectral sensitizers contained green or blue dyes .   The green sensitizing dye was used in a molar ratio of 4.5-1. More green present The sensitizing dye is SS-11, the green sensitizing dye present in smaller amounts is SS-1. It was 2.   The blue sensitizing dye is anhydro-5,5'-dichloro-3,3'-bis (3-su Rufopropyl) thiacyanine hydroxide, triethylammonium salt (Eox = 1.39 V, Ered = -1.38, Eox-Ered = 2.77 V ) (SS-13).   The sensitized emulsion was combined with a cyan dye-forming coupler (CC-1) and Silver coating amount 807mg / m on true film support²(75 mg / ft²) Was. Each coating sample was exposed with a tungsten light source for 1/50 second. Blue increase The sensitive film sample is Wratten 2B (which transmits wavelengths longer than 390 nm). Exposed through a (trademark) filter. The green intensifying film sample is Wratten Exposed through a 9 ™ filter. The exposed film sample is Kodak F Lexicoror C-41 (trademark) color negative treatment for 3 minutes 15 seconds I imaged.   Sensitivity was measured as described above.   The presence of the SET dopant in the blue or green spectrally sensitized emulsion results in sensitivity It is obvious that it will increase. Example 5   The purpose of this example is to use cyanine dyes with Eox-Ered <2. More predictable than cyan dyes that do not satisfy this relationship in the inventive SET-doped emulsion It is to show a large increase in sensitivity to the outside. Unless otherwise specified, emulsion characteristics and The details of the rum structure, exposure, and processing are as described in the above embodiment. .   Two sets of emulsions were selected and compared:   The properties of the cyanine dyes used for spectral sensitization are summarized below:   SS-14: Anhydro-6,6'-dichloro-3,3'-bis (3-sulfo Propyl) -5,5'-ditrifluoromethylbenzimidazolocarbocyanine Hydroxide, sodium salt Photo comparison   From Table XI, in the emulsions of this invention, the SET dopant was +0.87 volts. Shows a smaller oxidation potential (Eox) and a redox potential difference (Eox- Combination with one or more spectral sensitizing dyes having an Ered) of less than 2.10 volts. It is clear that the sensitivity is significantly increased in the above.

────────────────────────────────────────────────── ─── Continuation of front page    (81) Designated countries EP (AT, BE, CH, DE, DK, ES, FR, GB, GR, IE, IT, LU, M C, NL, PT, SE), JP (72) Inventor Black, Donald Lee             United States of America, New York 14580,             Webster, High Tower Way 803 (72) Inventor Brian And Roger Anthony             United States of America, New York 14626,             Rochester, Stone Fence Law             Do 214 (72) Inventor Olm, Miratoforn             United States of America, New York 14580,             Webster, Wycliffe Drive             181

Claims (1)

[Claims]   1. The silver halide grains comprising a dispersion medium and silver halide tabular grains. Has a face-centered cubic crystal lattice of rock salt type structure and edges and corners of the tabular grains It is a photographic-sensitive emulsion containing iodide adjacent to the surface forming hand,   Said tabular grains have a maximum surface iodide concentration along their edges,   The surface iodide concentration in the corner is lower than elsewhere along the edge, and   Present at a total concentration of less than 500 mppm based on silver and the surface concentration was finally deposited Provides shallow electron trap sites limited to less than 100 mppm based on 5% silver An emulsion characterized by containing a dopant which can be.   2. The tabular grains have a total iodide concentration of 20 mol% or less based on total silver. The emulsion according to claim 1, further characterized by:   3. The tabular grains contain at least 50 mole% bromide, based on total silver weight. The emulsion according to claim 1 or 2, further characterized by:   4. The maximum surface iodide concentration at the corners of the tabular grains is maximum edge surface iodide The method of claim 1 further characterized by being at least 0.5 mol% less than the concentration. The emulsion according to any one of items.   5. The maximum surface iodide concentration at the corners of the tabular grains is maximum edge surface iodide 5. The method of claim 4, further characterized by being at least 1.0 mol% lower than the concentration. Emulsion.   6. Dopants that can provide shallow electron trap sites are concentrated based on silver. Further characterized by being present at 10 to 300 mppm The emulsion according to any one of claims 1 to 5.   7. The surface concentration of the dopant that can provide the shallow electron trap site is the highest. Further characterized by being limited to less than 100 mppm based on 30% silver deposited later The emulsion according to any one of claims 1 to 6.   8. The emulsion further comprises a spectral sensitizing dye. The emulsion according to any one of 1 to 7.   9. The spectral sensitizing dye gives a positive value whose oxidation potential is less than +0.87 volt. Cyanine color as shown and having a potential difference between the oxidation potential and the reduction potential of less than 2.10 volts 9. The emulsion according to claim 8, further characterized by being elementary.   10. The cyanine dye has a potential difference of at least 1. between the oxidation potential and the reduction potential. The emulsion of claim 9 further characterized as being 10 volts.