Absorption silver bromide

Spectral Sensitization. The intrinsic absorption, and therefore the intrinsic photographic sensitivity, of silver bromide and silver iodobromide microcrystals falls off rapidly for wavelengths greater than 500 nm (see Fig. 2). In fact, silver chloride crystals have almost no sensitivity in the visible... 

Figure 43. Optical absorption spectra of silver chloride and silver bromide crystals at room temperature. A is the absorption coefficient, which is defined as the fractional decrease in transmitted light intensity due to absorption, per unit thickness [154], Figure adapted from [154],...

A study of the absorption of 2-pyrazolin-5-ones by silver bromide has been made by Stolyarova and Chel tsov.1348 These workers found that there was absorption of a unimolecular layer of pyrazolinones with the heterocyclic rings parallel to the absorbent surface. 

Assume that the sensitivity of x-ray film is proportional to the mass absorption coefficient of the silver bromide in the emulsion for the particular wavelength involved. What, then, is the ratio of film sensitivities to Cu Ka and Mo Ka radiation ... 

Carey Lea failed to find any sensitising action of dyes on ferric oxalate, potassium chromate, uranyl nitrate, etc. The research of J. M. Eder was fundamental in the study of sensitisation by dyestuffs. J. J. Acworth found a rough correlation between the absorption maximum of a coloured silver bromide gelatin plate and the maximum of chemical activity in the region of the spectrum, although this was always displaced towards the violet. The development of this work into panchromatic plates is well known. 

To photography we owe the discoveiy of radioactivity. The photographic emulsions produced nowadays for detecting radioactivity contain 80% or more of silver bromide so that little of radiation energy is lost by absorption In the gelatin and the grains of silver are in close proximity. 

The attenuated total reflectance (ATR) technique is used commonly in the near-infrared for obtaining absorption spectra of thin Aims and opaque materials. The sample, of refractive index i, is placed in direct contact with a material which is transparent in the region of interest, such as thallium bromide/thallium iodide (known as KRS-5), silver chloride or germanium, of relatively high refractive index so that Then, as Figure 3.f8... 

AgBr films could be made in the same manner using various bromo-alco-hols. AgBr is colorless but is usually slightly brownish due to photolytic formation of small particles of metallic silver (this occurs much more strongly if deposition is carried out in room light, but formation of some brown coloration is stiU noticeable even if deposition is carried out in the dark). This coloration masked the optical absorption, which occurs mainly in the UV for AgBr. For bromides, triethanolamine was not needed. 

Note Highly polar solvent sweet, ethereal odor soluble in water flammable, burns with a luminous flame highly toxic by ingestion, inhalation and skin absorption miscible with water, methanol, methyl acetate, ethyl acetate, acetone, ethers, acetamide solutions, chloroform, carbon tetrachloride, ethylene chloride, and many unsaturated hydrocarbons immiscible with many saturated hydrocarbons (petroleum fractions) dissolves some inorganic salts such as silver nitrate, lithium nitrate, magnesium bromide incompatible with strong oxidants hydrolyzes in the presence of aqueous bases and strong aqueous acids. Synonyms methyl cyanide, acetic acid nitrile, cyanomethane, ethylnitrile. 

SAFETY PROFILE Similar in toxicity to bromides. Prolonged absorption of iodides may produce iodism, which is manifested by skin rash, mnning nose, headache, and irritation of mucous membranes. In severe cases, the skin may show pimples, boils, redness, black-and-blue spots, hives, and blisters. Weakness, anemia, loss of weight, and general depression may occur. Generally very soluble in water and easily absorbed into the body. The iodides of copper(I), lead(II), silver(I), and mercury(II) are poorly soluble in water. When heated to decomposition they can emit highly toxic fumes of r and iodine compounds. See also IODINE. 

Lemieux has given a detailed account of a possible mechanism for this reaction. It is suggested that absorption of a 1,2-cis-poly-O-acetylglycosyl bromide on the silver chloride facilitates the formation of carbonium ions which are stabilized (immediately they are formed) by assuming a 1,2-cyclic structure. Reaction of this cyclic intermediate with chloride ion then yields the 1,2-[Pg.220]

Early colorimetric methods for arsenic analysis used the reaction of arsine gas with either mercuric bromide captured on filter paper to produce a yellow-brown stain (Gutzeit method) or with silver diethyl dithiocarbamate (SDDC) to produce a red dye. The SDDC method is still widely used in developing countries. The molybdate blue spectrophotometric method that is widely used for phosphate determination can be used for As(V), but the correction for P interference is difficult. Methods based on atomic absorption spectrometry (AAS) linked to hydride generation (HG) or a graphite furnace (GF) have become widely used. Other sensitive and specihc arsenic detectors (e.g., AFS, ICP-MS, and ICP-AES) are becoming increasingly available. HG-AES, in particular, is now widely used for routine arsenic determinations because of its sensitivity, reliability, and relatively low capital cost. 

Sensitive extraction-spectrophotometric methods are based on the extractable (into CHCI3, 1,2-diehloroethane, benzene, or toluene) ion-associates of basic dyes and anionic Ag complexes with cyanide [35,36], iodide [37,38], and bromide [39]. In these methods, use has been made of such dyes as Crystal Violet [35,39], Brilliant Green [38,39], Malachite Green [39], Methylene Blue [36], and Nile Blue A [37]. In some of these methods the molar absorptivities are elose to MO [36,39]. A flotation method has been proposed, based on the addition compound [R6G ][Ag(SCN )2] [R6G ][SCN ] which is formed by silver ions (at pH 2-5) in the presence of thiocyanate and Rhodamine 6G (flotation with DIPE, the precipitated compound is washed and dissolved in acetone, e = 1.5-10 ) [40]. The complex Ag(CN)2 , associated with Crystal Violet, has been utilized in another flotation-spectrophotometric method of determining silver [41]. Silver has been determined also in a system comprising thiocyanate and Rhodamine B, as an aqueous pseudo-solution, in the presence of poly(vinyl alcohol) [42]. 

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