Absorption silver chloride

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... 

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... 

Two analytical methods for priority pollutants specified by the USEPA (38) use HPLC separation and fluorescence or electrochemical detection. Method 605, 40 CFR Part 136, determines benzidine and 3,3-dichlorobenzidine by amperometric detection at +0.80 V, versus a silver/silver chloride reference electrode, at a glassy carbon electrode. Separation is achieved with a 1 1 (v/v) mixture of acetonitrile and a pH 4.7 acetate buffer (1 M) under isocratic conditions on an ethyl-bonded reversed-phase column. Lower limits of detection are reported to be 0.05 /xg/L for benzidine and 0.1 /xg/L for 3,3-dichlorobenzidine. Method 610, 40 CFR Part 136, determines 16 PAHs by either GC or HPLC. The HPLC method is required when all 16 PAHs need to be individually determined. The GC method, which uses a packed column, cannot adequately individually resolve all 16 PAHs. The method specifies gradient elution of the PAHs from a reversed-phase analytical column and fluorescence detection with an excitation wavelength of 280 nm and an emission wavelength of 389 nm for all but three PAHs naphthalene, acenaphthylene, and acenaphthene. As a result of weak fluorescence, these three PAHs are detected with greater sensitivity by UV-absorption detection at 254 nm. Thus, the method requires that fluores-... 

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]

Vibrational Spectra. Infrared spectra were obtained by pressing the freshly prepared powders between silver chloride plates. In the case of CfiF AsF, products of thermal decomposition were present in each spectrum. By recording spectra at successive stages of decomposition, however, it was possible to distinguish those features due to the radical cation salt. In additicm to the characteristic absorptions due to Asp , ... 

Spectra of Xe-PtFt adducts.— The infrared spectrum of material deposited on silver chloride windows in a nickel-bodied gas cell was recorded. The composition of the adduct was Xe(PtF6)i,72. Only two peaks in the region 400-4000 cm. were assignable to the adduct 652 vs, 550 s. cm. h The visible and ultraviolet spectrum of material deposited on the windows of a silica gas cell was recorded. A single peak at 3825 A. was observed. The material absorbed strongly beyond 4000 A. No differences in the absorption spectra were noted for several separate adduct samples. 

The infrared spectrum, in the range 800— 400 cm.-, of a thin film of the salt, formed on the silver chloride windows of a nickel cell, shows a very strong absorption centred on 632 cm., assumed to be the pseudo-v, of octahedral" [PtF,]-. The spectrum is very. similar to that of dioxygenyl hexafluoroplatinate(v),. but different from that of [PtF,] salts which show their strongest absorption at 583 cm.- ... 

Figure 2. Polarized IR absorption spectrum of a collapsed monolayer of poly(y-n-decyl-i.-glutamate) air dried on a silver chloride plate.

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],...

The precipitate is uncharged at the equivalence point (neither ion is in excess). Colloidal precipitates, such as silver chloride, therefore tend to coagulate at this point, especially if the solution is shaken. This is just what we want for gravimetry, but the opposite of what we want here. Coagulation decreases the surface area for absorption of the indicator, which in turn decreases the sharpness of the end point. We can prevent coagulation of silver chloride by adding some dextrin to the solution. 

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