Arsenic absorption spectrum

The fusion curve of mixtures of arsenic and iodine shows no evidence of the formation of a pentiodide, but there is a eutectic, of freezing point 71-5° C., which has the approximate composition of this substance.5 The absorption spectrum of the solution in carbon disulphide is similar to that of a mixture of the triiodide and iodine.3... 

Extended X-ray absorption fine structure (EXAFS) spectrum Part of an X-ray absorption spectrum that is used to identify the coordination of atoms, estimate bond lengths, and determine the adsorption complexes on the surfaces of adsorbents. EXAFS spectra may provide useful information on the speciation (valence state), surface complexes, and the coordination of arsenic on adsorbents (e.g. (Randall, Sherman and Ragnarsdottir, 2001 Ladeira, et al. (2001) Teixeira and Ciminelli (2005) Kober, et al. (2005)) (compare with X-ray absorption spectroscopy (XAS), X-ray absorption near edge structure (XANES) spectra, and X-ray absorption fine structure spectroscopy (XAFS)). 

Arsenic trichloride reacts with dilithium phthalocyanine in dimethyl-formamide to yield chloroarsenic phthalocyanine 808), which does not react with silver ions in pyridine. Its absorption spectrum has been recorded (Section V,B), but little else is known of the complex. 

X-ray absorption near edge structure (XANES) spectrum An analysis from X-ray absorption spectroscopy (XAS) and, in particular, X-ray absorption fine structure (XAFS) spectroscopy. XANES can be used to identify the valence state of arsenic in solid samples (Teixeira and Ciminelli, 2005 Kober et al., 2005). 

FIGURE 7.14 X-ray absorption spectroscopy (XAS) spectrum of arsenate with the x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) regions indicated. (Reprinted from Luo, L., and S. Zhang, Sci. China Chem. 53, 12, 2529-2538, 2010. With permission from Science China Press.)... 

Arsenic, as the element with the shortest primary absorption wavelength in AAS, produces several AsO molecular bands around 250 nm if the conventional air/acetylene flame is used. An overview of the structures produced by the diatomic molecule is shown in Figure 7.15. Flere the electronic transition takes place between the X and the B state, while the vibrational excitation is changed in some cases. Apart from the two AsO bands with Av= +1 around 243.5 nm and Av= -1 around 256.3 nm, two systems without a change of the vibrational excitation exist. The latter can be divided into the so-called subsystems I and II, showing pronounced band heads around 250.4 nm and 257.0 nm, respectively. In Figure 7.16 the enlarged spectrum of the electronic transition to the B state with Av = 0 (subsystems I) is depicted. 

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