JPH08211541A - Silver halide photographic component and stabilization method of photosensitive silver halide emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver halide photographic component and a method for stabilizing a photosensitive silver halide emulsion. SOLUTION: This method for stabilizing a photosensitive silver halide emulsion comprises steps of a) adding water-soluble bromide salt to the emulsion; and b) adding a compound expressed by formula I (Wherein R represents nitro, cyano, fluoroalkyl, halogen, or -COOR<1> group, and R<1> represents hydrogen or alkyl group, and n represents an integer of 1-5) or formula II (wherein R<2> represents a branched alkyl chain having 3-5 carbon atoms) to the spectral sensitized emulsion.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a silver halide photographic element and a method for stabilizing a photosensitive silver halide emulsion.

[0002]

2. Description of the Related Art For example, US Pat. Nos. 2,444,607 and 2,44
It is known to those skilled in the art to stabilize silver halide emulsions with respect to storability using the azaindene compounds disclosed in 4,609, 2,449,225 and 2,450,397.

US Pat. Nos. 2,772,164 and 2,835,581,
No. 3,333,961 discloses chemically or spectrally sensitized silver halide emulsions containing specific types of triazaindenes, tetraazaindenes and pentaazaindenes as antifoggants.

US Pat. Nos. 3,418,130, 3,462,272 and 3,563,755 disclose silver halide emulsions containing certain types of triazaindenes as antifoggants which are added after chemical or physical ripening. There is. Photographic materials stabilized with tetraazaindene derivatives show good photosensitivity properties shortly after coating, but show poor storage properties with poor contrast values and increased speed and D _max values.

TH James's The Theory
The Theory of
The Photographic Process), 4th Edition, p. 396, discloses various compounds which act as antifoggants and stabilizers. Of the inorganic compounds shown, the most useful are the soluble bromides, Group VIII complex salts of the Periodic Table,
And salts of mercury, cadmium, zinc and manganese. A number of organic compounds are also disclosed, such as triazoles, tetrazoles, benzotriazoles, oxazoles, thiazoles, nitrobenzimidazoles, nitroindazoles, some compounds containing -SH groups, and the like.

The silver halide photographic red-sensitive material is especially about 600
It is suitable for exposure in the region of about 700 nm, for example, using a He-Ne (633 nm) laser or a red diode (650, 670 nm) laser. The red-sensitive material has a silver halide emulsion, which generally has a high content of silver chloride (for example, 50 mol% or more, preferably 60 mol% or more), and an average particle size of 0.30 μm.
It contains a silver chlorobromide emulsion having m or less.

The red-sensitive material must be stabilized in order to retain good light-sensitive properties after long-term storage. This is a particular problem for this type of material. These materials show good photosensitivity values with respect to the speed and contrast values of the new materials obtained, for example, by the addition of soluble halides, but show undesired changes in these values during storage. On the contrary, the red-sensitive material may show good storage stability when stabilized with a tetrazole derivative compound, but the speed of the new material is very slow.

US Pat. No. 4,332,888, a) provides the emulsion with a stabilizer sufficient to stop chemical ripening without interfering with the spectral sensitization, b) spectrally sensitizes the emulsion, c) From the water-soluble bromide salt, 1-phenyl-5-mercaptotetrazole compound and hydroxytriazaindene, aminotriazaindene, hydroxytetraazaindene, aminotetraazaindene, hydroxypentaazaindene and aminopentaazaindene to the emulsion. A method of stabilizing a photosensitive silver halide emulsion by adding a stabilizer selected from the group is disclosed. Preferably, the stabilizer in step a) is similar to that in step c), but any material that stops chemical ripening may be used. The method provides short term stability during spectral sensitization. Long-term stability is provided by the spectral sensitization followed by the introduction of the combination of said stabilizers in step c). The emulsions disclosed in that patent do not contain chloride, contain 6% iodide and 94% bromide, which is particularly useful for color diffusion transfer film units and silver diffusion transfer film units.

US Pat. No. 4,536,473 discloses a photosensitive material containing an emulsion layer having silver halide grains containing at least silver chloride, which material is prepared by using a tricarbocyanine or dicarbocyanine dye. Sensitized to infrared rays. The emulsion layer contains 0.0003 to 0.01 mole of water-soluble bromide per mole of silver, such as ammonium bromide, potassium bromide, sodium bromide and lithium bromide.

US Pat. No. 4,794,070 discloses a photographic element comprising a substrate layer and at least one silver halide photographic emulsion on one side of the substrate, the element containing silver halide. However, it contains at least 0.1 g / m ² of bromide ion as an alkali water-soluble bromide salt. The emulsion is sensitized by infrared radiation. Addition of the bromide salt to radiographic elements reduces developer compound variability.

U.S. Pat. No. 4,786,588 describes halogenation to give a highly sensitive sulfur-sensitized silver halide emulsion which is halogen-exchanged by adding a certain amount of water-soluble bromide immediately before or during sulfur sensitization. Silver particles are disclosed. If a sulfur sensitizer is added to the emulsion long after the addition of the water-soluble bromide, the addition of the water-soluble bromide has little effect on increasing sensitivity. On the contrary, when the water-soluble bromide is completely aged to obtain the highest sensitivity by adding the above-mentioned sulfur sensitizer to the emulsion and then added to the emulsion, the sensitivity of the emulsion is not increased but is rather lowered.

US Pat. No. 5,068,167 discloses a high contrast photographic material containing a silver halide emulsion associated with hydrazine, the material comprising a water soluble bromide and a water soluble bromide added to the emulsion at a suitable stage during preparation. / Or have reduced fogging due to the presence of water soluble chlorides. The addition is generally carried out after the washing step and may be added with any sensitizing dye as is conventional.

US Pat. No. 4,830,958 discloses a color light-sensitive photographic material which is excellent in high-speed processability and has no change in sensitivity due to changes caused by preparation of the material. It comprises at least one silver halide emulsion layer containing chloride rich silver halide grains, a water soluble bromide and a high boiling organic solvent for dispersing the photographic coupler. The water-soluble bromide may be added at any time from the completion of chemical ripening of the silver halide emulsion to the coating of the emulsion.

European Patent Application No. 440,947 discloses an infrared sensitive silver halide photographic element wherein at least one infrared sensitized emulsion layer comprises at least one electron withdrawing group such as a fluoroalkyl group. Is associated with the 1-aryl-5-mercaptotetrazole group substituted by the aryl group.

Japanese Patent Application No. 04-329,536 discloses a silver halide photographic element supersensitized with a phenylmercaptotetrazole compound having at least one trifluoromethyl group as a substituent of a benzene ring.

Good initial sensitivity values, especially with respect to speed values,
And it is useful to have photographic elements that exhibit good preservability with respect to speed and contrast values.

It is also useful to add a stabilizer prior to spectral sensitization to allow the photographic element to reach good stability immediately without adversely affecting the photosensitivity.

[0018]

[Means for Solving the Problems]

 a) adding a water-soluble bromide salt to the emulsion; b) spectrally sensitizing the emulsion; c) adding the following formula (I) to the spectrally sensitized emulsion:

[Chemical 15] (Wherein R represents a nitro, cyano, fluoroalkyl, halogen, —COOR ₁ group, R ₁ is hydrogen or an alkyl group, and n is an integer of 1 to 5); or the following formula (II ):

Embedded image Wherein R ₂ is a branched alkyl chain having 3 to 5 carbon atoms, the method of stabilizing a photosensitive silver halide emulsion.

The method of the present invention provides a photographic element that exhibits good initial sensitometric values and good storability, especially with respect to speed and contrast values.

In another aspect, the present invention provides a photosensitive halogen comprising a support having at least one photosensitive silver halide emulsion layer containing a water soluble bromide salt and a compound of formula (I) or (II) above. It relates to a silver halide photographic element.

In stabilizing the light-sensitive silver halide emulsion, the water-soluble bromide salt includes various compounds capable of dissociating the bromide in water. For example, bromide salts such as ammonium bromide, potassium bromide, sodium bromide, lithium bromide and the like may be used. Further, a suitable organic bromide such as tetraethylammonium bromide, ethylpyridinium bromide, etc. may be used. However, of the bromide salt,
Cadmium bromide, zinc bromide, and the like are toxic if they are absorbed into the human body in excess. Therefore, a water-soluble bromide which is not harmful to the living body (non-toxic) is preferable as described above.

The water-soluble bromide added to the silver halide emulsion is used in an amount sufficient to substantially improve the sensitivity of the emulsion and / or substantially prevent aging of sensitivity. The amount of water-soluble bromide may vary over a wide range, and the bromide content should be approximately 1 mole per silver mole before spectral sensitization.
Particularly favorable results are obtained when added in an amount of 0.05 to about 2 mmol, preferably about 0.2 to about 1.70 mmol.

Before the spectral sensitization, the water-soluble salts are used to obtain better photosensitivity values, especially higher speeds with new materials, and to reduce the variability of the photosensitivity values in the incubation test. Must be added.

After adding the water-soluble salt to the emulsion, the emulsion is spectrally sensitized. The spectral sensitizers used in this invention are, for example, about 62 using He-Ne (633 nm) laser and red diode (650,670 nm) laser exposure.
Are known to those skilled in the art which are suitable for exposure in the region of 0 to about 680 nm. Useful spectral sensitizers include, for example, US Pat.
Trinuclear merocyanine dyes having benzothiazole or benzoselenazole groups disclosed in 5,116,722; Merocyanine spectral sensitizing dyes containing at least two acid groups disclosed in Swiss Patent Application No. 677,409; US Pat. No. 4,717,65
Benzimidazole pentacarbocyanine spectral sensitizers disclosed in No. 0; dyes containing a quinoline group disclosed in US Pat. No. 4,336,323; and trinuclear merocyanines disclosed in EP 607,478 and pending European patent application 93115561.8. There is a dye;

The spectral sensitizing dye used in the present invention may be prepared by any method known to those skilled in the art, such as James's The Theory of the Photographic Process.
y of the Photographic Process '', MacMillan
lan), 4th edition, 1977.

The spectral sensitizing dye used in the present invention is 0.01 to 0.20 per mol of silver in a silver halide emulsion.
It is introduced in a content of g, preferably 0.02 to 0.16 g.

The spectral sensitizing dye useful in the present invention may be dispersed directly in the emulsion. Furthermore, they are first prepared in a suitable solvent, such as methyl alcohol, methyl cellosolve,
It may be dissolved in acetone, water, pyridine or a mixture thereof and added to the emulsion as a solution. A method for adding a sensitizing dye to a photographic emulsion is disclosed in US Pat.
3,469,987, 3,676,147, 3,822,135, 4,19
9,360 and 2,912,343, 3,342,605, 2,99
6,287 and 3,429,835. Disperse the above-mentioned sensitizing dye in a silver halide emulsion,
They may be coated on a suitable support. Of course, the dispersion method may be carried out at any suitable stage of preparation of the silver halide emulsion.

Any type of silver halide photographic emulsion may be used in the practice of this invention. Silver chloride, silver bromide,
Silver iodobromide, silver chlorobromide, silver chloroiodobromide and mixtures thereof may be used, for example dispersed in a hydrophilic colloid or a binder. Any arrangement of grains, cubic, orthorhombic, hexagonal, epitaxial or tabular (high aspect ratio) grains may be used. The colloid may be partially hardened or fully hardened by any known photographic hardener. Such hardeners include, for example, U.S. Patent Nos. 3,232,764 and 2,8.
70,013, 3,819,608, 3,325,287, 3,992,36
Free aldehydes, aldehyde-releasing compounds, triazines and diazines, aziridines, vinyl sulfones, carbodiimides and the like as disclosed in No. 6, No. 3,271,175 and No. 3,490,911 may be used.

In addition, during formation of silver halide grains or during physical ripening, a cadmium salt, a sulfite, a lead salt, a thallium salt, a rhodium salt or a ruthenium salt or a ruthenium complex salt is added to the silver halide emulsion. May be.

In the above formula (I), R may be a nitro, cyano, fluoroalkyl, halogen (preferably chlorine or bromine) or --COOR ₁ group, wherein R ₁ is hydrogen or 1 to 5 carbon atoms. Is an alkyl group having (for example, methyl, ethyl, n-butyl, etc.), and n is 1 to
It is an integer of 5.

Preferably, in the above formula (I), R is a linear or branched fluoroalkyl group having 1 to 4 carbon atoms, the alkyl group having at least one fluorine atom per carbon atom, Preferably 1.5 fluorine atoms,
More preferably, it has all hydrogen atoms substituted with fluorine atoms.

When the term "group" or "ring" is used herein, the chemical entity includes the basic group or ring and groups or rings with conventional substituents.
When the term "moiety" is used, it includes only unsubstituted chemicals. For example, "alkyl group
The term `` p) '' includes such alkyl moieties such as methyl,
Not only ethyl, octyl, stearyl, etc., but also substituents,
It is meant to include such moieties including, for example, halogen, cyano, hydroxy, nitro, amine, carboxylate and the like. Contrary to this, the “alkyl part (alk
The term "yl moiety)" includes only methyl, ethyl, octyl, stearyl, cyclohexyl and the like.

In the above formula (II), R ₂ is a branched alkyl chain having 3 to 5 carbon atoms, preferably t-butyl.

Illustrative examples of compounds of formulas (I) and (II) are given below, but the invention is not limited to these compounds.

[Chemical 17]

The compound of formula (I) is added to the silver halide photographic emulsion in an amount of about 0.05 to about 2.0 millimoles, preferably about 0.20 to about 1.70 millimoles per mole of silver.

The silver halide emulsion may be chemically sensitized with a conventional sensitizer. Sulfur-containing compounds,
Gold and noble metal compounds and polyoxyalkylene compounds are particularly suitable. Methods for chemically sensitizing silver halide emulsions include, for example, Research Disclosure (Rese
Arch Disclosure) 17643, Section III, 1978.

Other conventional photographic addenda that may be added to the silver halide emulsion, such as coating aids, antistatic agents, acutance dyes, antihalation dyes and layers, antifoggants, latent image stabilizers. , Supersensitizer,
Anti-kinking agent, high-strength reciprocity law failure (re
ciprocity failure) reducing agent, plasticizer, matting agent, developer,
Color couplers, absorbing materials and scattering materials may be found in Research Disclosure 17643, 1
It was disclosed in 978.

Gelatin is commonly used as a hydrophilic colloid for the silver halide photographic elements of this invention. As hydrophilic colloids, gelatin derivatives, natural substrates such as albumin, casein, agar, alginic acid, etc., and hydrophilic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, cellulose ethers, partially hydrolyzed polyvinyl acetate, etc. , May be used in addition to or in place of gelatin. Further, the gelatin may be partially replaced with a polymer latex obtained by emulsion polymerization of vinyl monomers, such as polyethyl acrylate latex, to improve the physical properties of the photographic layer.

The support used in the silver halide photographic element of the present invention is a support that has been conventionally used, for example, glass, cloth, metal such as cellulose acetate, cellulose acetate butyrate, cellulose nitrate, polyester (eg polyethylene). A film containing terephthalate or polyethylene naphthalate), polyamine, polystyrene and the like; paper including varita, coated paper, resin coated paper and the like may be used.

The silver halide emulsions of the present invention can be used as light-sensitive emulsions for various photographic elements, such as negative emulsions of high surface or internal sensitivity, surface positive or non-cloudy direct positive emulsions, printout emulsions, reversals. It may be used as an emulsion, an emulsion for black and white materials, a color material, a radiographic material, a color transfer material and the like.

As is known to those skilled in the art, the photographic elements of this invention have been processed to form a silver halide with an alkaline aqueous medium.
Visible images can be formed by association in the presence of developers contained within the medium or within the photographic element. In the case of color photographic elements, the processing includes at least one color developing tank, optionally a pre-hardening tank, a neutralizing tank, a first (black and white) developing tank and the like. These and other baths that complete the photographic process (eg) are known to those skilled in the art and are disclosed, for example, in Research Disclosure 17643, 1978. The invention is illustrated by the examples below.

[0042]

【Example】

Example 1 Monodispersed cubic silver chlorobromide emulsion (64% chloride, 36%
% Bromide), which has a mean particle size of 0.28 μm,
Iridium and ruthenium compounds were doped in an amount of 0.3 and 0.6 mol per mol of silver, respectively. The emulsion was chemically sensitized with gold, thiosulfate and p-toluenethiosulfate and stabilized with 2-methylthio-4-methyl-6-hydroxy-triazaindolizine.

The emulsion was spectrally sensitized with a trinuclear merocyanine dye with maximum absorption at 569 and 608 nm in methyl alcohol. The emulsion was silver-coated on a polyester substrate primed with polyvinylidene chloride 4.
A coating was formed by coating with 3 g / cm ² (Sample 1).

Samples 2-10 were added with potassium bromide salt,
A sample was prepared in the same manner as sample 1 except that the spectral sensitizing dye was added, and the compound (1) of the present invention was added in the amount shown in Table 1 after the spectral sensitizing dye was added.

[0045]

[Table 1]

The sample was exposed to a 670 nm red diode laser for a dwell time of 10 ^-6 seconds, developed with 3M RDC V fast access compound at 32 ° C. for 30 seconds and then evaluated. Table 2 shows the results obtained on the freshly coated material. Table 3 shows the rate of change in the photosensitivity value obtained after the incubation test (50% RH, 60 ° C. for 5 days). D for the photosensitivity result
_{Includes min} , speed, average contrast and shoulder contrast. The higher the contrast, the better the dot image quality obtained. D _min is the minimum density on the exposed side of the calibration point, and velocity was calculated by Log20 / E (E is expressed in lux seconds) at a density of 0.20 above D _min . The tow contrast corresponds to the absolute value of the slope of the line connecting the density points 0.07 and 0.17 above D _min . The average contrast corresponds to the absolute value of the slope of the line connecting the density points of 0.10 and 2.50 above D _min , and the shoulder contrast corresponds to the absolute value of the slope of the line connecting the density points of 1.60 and 4.00 above D _min. To do.

[0047]

[Table 2]

[Table 3]

Tables 2 and 3 show that Samples 2-4 containing potassium bromide but no stabilizing compound show an increase in speed and a slight decrease in contrast relative to the control sample for its freshly coated material. , The contrast value reduction still remained ineligible after the sample was incubated. In fact, if the variation of the contrast value is 15% or less, it is considered to be suitable for the present invention. Samples 5 to 8 containing the compound (1) of the present invention but no potassium bromide have very low shoulder contrast (11.
0 or less) and speed. Samples 9 and 10 containing both potassium bromide and the compound (1) of the present invention imparted good speed and contrast values to the freshly coated material, the photosensitivity of which, even after the incubation test, was that of control sample 1 It was much lower, very good with a slight increase in velocity fluctuations and a slight fluctuation in contrast values.

Example 2 Sample 11 was prepared like Sample 10 of Example 1 except that the amount of compound (1) was 0.13 mmol / mol silver. Sample 12 was replaced with the compound of the present invention in place of the compound (1) of the present invention.
It was prepared in the same manner as Sample 11 except that (2) was used. Sample 13
Was prepared in the same manner as in Sample 11, except that the compound (1) of the present invention was replaced by 0.50 mmol of the compound (5) of the present invention per mol of silver. Sample 14 was prepared in the same manner as Sample 11 except that the compound (1) of the present invention was replaced with 0.50 mmol of the compound (6) of the present invention per mol of silver. Sample 15 was prepared in the same manner as Sample 11 except that Comparative Compound A was used instead of Compound (1) of the present invention. Sample 16 is the compound (1) of the present invention.
Was prepared in the same manner as in Sample 11, except that Comparative Compound B was used instead of. Sample 17 was prepared in the same manner as Sample 11 except that Comparative Compound C was used instead of Compound (1) of the present invention. Sample 18 was prepared as Sample 11 except that Comparative Compound D was used in place of Compound (1) of the invention. Sample 19
It was prepared in the same manner as in Sample 11, except that Comparative Compound E was used instead of Compound (1) of the present invention. Sample 20 was prepared in the same manner as Sample 11, except that the compound (1) of the present invention was replaced with 0.50 mmol of the comparative compound E per mol of silver. The samples were evaluated after exposure as described in Example 1. Table 4 shows the photosensitivity results obtained with the freshly coated material;
Table 5 shows the rate of change in the photosensitivity value obtained after the incubation test (50% RH, 60 ° C. for 5 days).

[0050]

[Table 4]

[Table 5]

Table 4 shows that all freshly coated samples have good photosensitivity properties, but as shown in Table 5, only samples 11-14 of the invention were obtained by the incubation test. There was almost no change in the photosensitivity value.

Example 3 Sample 21 was prepared as Sample 11 of Example 2 except that the potassium bromide salt was added after the addition of the spectral sensitizing dye in Sample 11 rather than before. Sample 22 was prepared like Sample 11 without the addition of compound (1). Sample 23 was prepared as Sample 22 except that the potassium bromide salt was added after the addition of the spectral sensitizing dye in Sample 22, rather than before. The sample was evaluated post-exposure as described in Example 1. Table 6 shows the photosensitivity results obtained with the freshly coated material; Table 7 shows the rate of change of the photosensitivity values obtained after the incubation test (50% RH, 60 ° C. for 5 days). showed that.

[Table 6]

[Table 7]

Table 6 shows that comparative sample 21, obtained by adding potassium bromide after the spectral sensitizing dye, has a lower rate for the freshly coated material and has a very high photosensitivity value according to the incubation test. It was shown to have a large change. On the other hand, Sample 11, which was identical to Sample 21 except that it was obtained by adding potassium bromide before the spectral sensitizing dye, showed very good storage stability.

Embedded image

Front Page Continuation (72) Inventor Giuseppe Roblio, Italy, I-17016 Ferrania (Savona) (No address is shown) 3M Italy, Richerche Societa Per Achini

Claims (22)

[Claims] 1. A) adding a water-soluble bromide salt to the emulsion; b) spectrally sensitizing the emulsion; c) adding the following formula (I) to the spectrally sensitized emulsion: (Wherein R represents a nitro, cyano, fluoroalkyl, halogen, —COOR ₁ group, R ₁ is hydrogen or an alkyl group, and n is an integer of 1 to 5); or the following formula (II ): [Chemical 2] Wherein R ₂ is a branched alkyl chain having 3 to 5 carbon atoms, the method of stabilizing a photosensitive silver halide emulsion. 2. The method for stabilizing a photosensitive silver halide emulsion according to claim 1, wherein the water-soluble bromide salt is ammonium bromide or potassium bromide. 3. The compound has the following formula: The method for stabilizing a photosensitive silver halide emulsion according to claim 1, wherein R is fluoroalkyl, and n is an integer of 1 to 5. 4. The compound has the following formula: The method for stabilizing a photosensitive silver halide emulsion according to claim 1, which comprises: 5. The compound has the following formula: The method for stabilizing a photosensitive silver halide emulsion according to claim 1, which comprises: 6. The compound has the following formula: The method for stabilizing a photosensitive silver halide emulsion according to claim 1, which comprises: 7. The compound has the following formula: The method for stabilizing a photosensitive silver halide emulsion according to claim 1, which comprises: 8. A process for stabilizing a photosensitive silver halide emulsion according to claim 1, wherein said emulsion is spectrally sensitized with a sensitizing dye suitable for exposure in the region of about 620 to 680 nm. 9. The method of stabilizing a photosensitive silver halide emulsion according to claim 1, wherein the emulsion is doped with iridium, ruthenium and / or rhodium dopants. 10. A water-soluble bromide salt and the following formula (I): (Wherein R represents a nitro, cyano, fluoroalkyl, halogen, —COOR ₁ group, R ₁ is hydrogen or an alkyl group, and n is an integer of 1 to 5); or the following formula (II ): A photosensitive silver halide comprising a support having at least one photosensitive silver halide emulsion layer containing a compound having a compound of the formula: wherein R ₂ is a branched alkyl chain having 3 to 5 carbon atoms. Photographic component. 11. The light-sensitive silver halide photographic element according to claim 10, wherein the water-soluble bromide salt is ammonium bromide or potassium bromide. 12. The compound has the following formula: 11. The light-sensitive silver halide photographic element according to claim 10, having (wherein R represents fluoroalkyl and n is an integer of 1 to 5). 13. The compound has the following formula: A light-sensitive silver halide photographic element according to claim 10 having 14. The compound has the following formula: A light-sensitive silver halide photographic element according to claim 10 having 15. The compound has the following formula: A light-sensitive silver halide photographic element according to claim 10 having 16. The compound has the following formula: A light-sensitive silver halide photographic element according to claim 10 having 17. The emulsion is spectrally sensitized with a sensitizing dye suitable for exposure in the region of about 620-680 nm.
0. The light-sensitive silver halide photographic element described in 0. 18. A photosensitive silver halide photographic element according to claim 10 wherein said emulsion is doped with iridium, ruthenium and / or rhodium dopants. 19. A light-sensitive silver halide photographic element according to claim 10 wherein said emulsion is a chlorobromide emulsion having a chlorine content of at least 50 mol%. 20. The emulsion has an average particle size of 0.30 μm
A light-sensitive silver halide photographic element according to claim 10 having the following: 21. The amount of said compound is about 0.05 per mol of silver.
11. The light sensitive silver halide photographic element of claim 10 in the range of about 2.0 millimolar. 22. The amount of said compound is about 0.20 per mole of silver.
The light-sensitive silver halide photographic element of claim 10 in the range of about 1.70 millimolar.