Atomic spectra examples

A convenient method is the spectrometric determination of Li in aqueous solution by atomic absorption spectrometry (AAS), using an acetylene flame—the most common technique for this analyte. The instrument has an emission lamp containing Li, and one of the spectral lines of the emission spectrum is chosen, according to the concentration of the sample, as shown in Table 2. The solution is fed by a nebuhzer into the flame and the absorption caused by the Li atoms in the sample is recorded and converted to a concentration aided by a calibration standard. Possible interference can be expected from alkali metal atoms, for example, airborne trace impurities, that ionize in the flame. These effects are canceled by adding 2000 mg of K per hter of sample matrix. The method covers a wide range of concentrations, from trace analysis at about 20 xg L to brines at about 32 g L as summarized in Table 2. Organic samples have to be mineralized and the inorganic residue dissolved in water. The AAS method for determination of Li in biomedical applications has been reviewed . 

For example, they are used in producing high quality hard disc recorder headers. STM also provides the possibility of observing electrochemical reactions and atomic spectrum. 

The rare earth elements are different from other elements because the optical transitions between levels of the fn configuration are inherently very sharp-lined and have well-resolved structure characteristic of the local crystal fields around the ion. In minerals, this characteristic provides an excellent probe of the local structure at the atomic level. Examples will be shown from our work of how site selective laser spectroscopy can be used to determine the thermal history of a sample, the point defect equilibria that are important, the presence of coupled ion substitution, the determination of multiple phases, and stoichiometry of the phase. The paper will also emphasize the fact that the usefulness and the interpretation of the rare earth luminescence is complicated by the presence of quenching and disorder in mineral samples. One in fact needs to know a great deal about a sample before the wealth of information contained in the site selective luminescence spectrum can be understood. 

C NMR spectroscopy is used to determine the substitution patterns in disubstituted benzenes, because each line in a spectrum corresponds to a different kind of carbon atom. For example. 0-, m-, and p-dibromobenzene each exhibit a different number of lines in its C NMR. spectrum,... 

Similar shift-changes were found in pyranoses that have an a.e,a arrangement of three oxygen atoms for example, in the spectrum of methyl a-D-allopyranoside, the H-2 signal shifts to the greatest extent, followed by those of H-3 and H-1 in that of 1,6-anhydro-yS-D-allopyranose, the H-3... 

The high order one-dimensional approach was first used to consider the inversion spectrum of ammonia along the v2 inversion axis [45]. A similar calculation has been used to examine the influence of solvent on the splitting due to tunneling when a hydrogen atom, for example, can move between two positions of equilibrium [46],... 

The mass spectrum of RhFj is not typical of a metal pentafluoride, and is relatively rich in ions containing more than one Rh atom. For example, as the temperature increases, the concentration of Rh2p9 ion increases at the expense of monomeric RhFs" and RhFj fragments. 

X-ray absorption is usually measured by (1) transmission by counting the number of X-rays transmitted through the sample (and the difference between the incident number of X-rays and those transmitted is the amount absorbed) and/or (2) fluorescence whereby the energy released during the back-fiUing of the empty core hole after the electron has been excited is related to the number of X-rays absorbed by the atom. An example of an X-ray absorption spectmm is shown for PbS in Fig. 3. A full spectrum is typically collected from 200 electron volts (eV) below an absorption edge to 1,000 eV above the edge (Kelly et al. 2008). 

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