Gallium metal impurities, analysis

Table III. Analysis of Gallium Metal Impurities in ppm Weight...

Atomic absorption spectroscopy of VPD solutions (VPD-AAS) and instrumental neutron activation analysis (INAA) offer similar detection limits for metallic impurities with silicon substrates. The main advantage of TXRF, compared to VPD-AAS, is its multielement capability AAS is a sequential technique that requires a specific lamp to detect each element. Furthermore, the problem of blank values is of little importance with TXRF because no handling of the analytical solution is involved. On the other hand, adequately sensitive detection of sodium is possible only by using VPD-AAS. INAA is basically a bulk analysis technique, while TXRF is sensitive only to the surface. In addition, TXRF is fast, with an typical analysis time of 1000 s turn-around times for INAA are on the order of weeks. Gallium arsenide surfaces can be analyzed neither by AAS nor by INAA. 

The conventional method for quantitative analysis of gallium in aqueous media is atomic absorption spectroscopy (qv). High purity metallic gallium is characterized by trace impurity analysis using spark source (15) or glow discharge mass spectrometry (qv) (16). 

He also concluded that at such concentrations the ions in the vicinity of the electrode are exhausted by reduction and that the current intensity depends mostly on the number of metal ions transported into this space by diffusion. He also pointed out that the position of the wave on the potential axis is characteristic of the reduced species and can be used for qualitative analysis. From occurrence of waves at -0.4 and -0.6 V in solutions prepared from metallic zinc, it was possible to conclude the presence of two impurities, attributed tentatively to indium and gallium. M. Shikata at the same meeting reported (11) the possibility of carrying out the reduction at the D.M.E. in a nonaqueous system - in sodium ethoxide. In the following year the Japanese chemist reported also the first reduction of an organic compound, nitrobenzene (12,13). 

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