Manganese absorbance

Intermetallic compounds of zirconium with kon, cobalt, and manganese absorb and desorb considerable amounts of hydrogen, up to ZrMri2 [68417-38-9] (128) and ZrV2H 2 [63440-37-9] (129). These and other zirconium intermetallic compounds are being extensively studied for possible hydrogen storage appHcations (130). 

Aspirate solutions into a stoichiometric air—acetylene flame and measure manganese absorbance at 279.48 nm. 

Only a small (ca 3%) fraction of ingested or inhaled manganese is absorbed, which occurs primarily by the intestines (209). Once absorbed, manganese is regulated by the Hver, where it is excreted into the bile and passes back into the intestine, where some reabsorption may occur (210). Manganese is elirninated almost exclusively (>95%) by the bile in the gastrointestinal tract. 

The above considerations will be illustrated by the simultaneous determination of manganese and chromium in steel and other ferro-alloys. The absorption spectra of 0.001 M permanganate and dichromate ions in 1M sulphuric acid, determined with a spectrophotometer and against 1M sulphuric acid in the reference cell, are shown in Fig. 17.20. For permanganate, the absorption maximum is at 545 nm, and a small correction must be applied for dichromate absorption. Similarly the peak dichromate absorption is at 440 nm, at which permanganate only absorbs weakly. Absorbances for these two ions, individually and in mixtures, obey Beer s Law provided the concentration of sulphuric acid is at least 0.5M. Iron(III), nickel, cobalt, and vanadium absorb at 425 nm and 545 nm, and should be absent or corrections must be made. 

Figure 5.18 is an absorbance versus time plot obtained by Hoenig and Wollast [681] for the determination of trace metals in seawater. It shows the absorbance profiles of the desired elements as a function of the atomisation temperature. The scale starts with cadmium, for which the absorption signal appears around 400 °C, followed by lead (756 °C), copper (1000 °C), manganese (1200 °C), nickel (1300 °C), and chromium (140 °C). 

The results demonstrate that cadmium can be determined directly the direct determination of copper, manganese, and chromium is also possible, but their application is more limited than cadmium. The lead and nickel determination proved to be the most difficult, since their determination is limited by their low sensitivity and by the overlap of their absorption profiles with the background absorbance generated by seawater matrix. The direct determination of lead and nickel by this technique can be used only for seawater samples taken in coastal or estuarine zones that are quite polluted. 

Of more apparent significance in the aquatic environment are redox processes induced or enhanced on absorbance of light by chromophores at metal oxide surfaces in which the metal of the oxide lattice constitutes the cationic partner. Light induced electron transfer within such a chromophore often results in disruption of the oxide lattice. The photoredox-induced dissolution of iron and manganese oxides by such a mechanism has been proposed as a possible means of supply of essential trace-metal nutrients to plants and aquatic organisms (29-31). ... 

Nonradiative energy transfer is very often used in practical applications, such as to enhance the efficiency of phosphors and lasers. A nice example is the commercial phosphor Cas(P04)3 (FCl), which is doubly activated by Sb + and Mn + ions. When the phosphor is singly activated by Mn + ions, it turns out to be very inefficient, due to the weak absorption bands of the divalent manganese ion. However, coactivation with Sb + ions produces a very intense emission from the Mn + ions, because the Sb + ions (the donor centers) efficiently absorb the ultraviolet emission (253.6 nm) of... 

TEA chloride See tetraethylammonium chloride., te,e a klorjd ) technetium chem A transition element, symbol Tc, atomic number 43 derived from uranium and plutonium fission products chemically similar to rhenium and manganese isotope Tc has a half-life of 200,000 years used to absorb slow neutrons in reactor technology. tek ne-she-om ... 

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