Germanium analytical method

As described in Section 3.1, Baier et al. (1974) have used a machined germanium prism to sample surface organic monolayers in the manner developed earlier by Blodgett (1934,1935) for fatty acid films. The basis of their analytical method, infrared spectroscopy by the technique of internal reflections inside the machined prisms, is only qualitative but serves very well to examine the chemical nature of the surface organics. It is well known that when an internal reflection prism made of a material with a sufficiently high index of refiraction such as germanium is used, the internal reflection IR spectrum obtained suffers no band distortion or band shift when compared to conventional transmission spectra of the same substance (Barr and Flournoy, 1969). 

The introduction of high-resolution, high-efficiency /-ray detectors composed of lithium-drifted germanium crystals has revolutionised /-measurement techniques. Thus, /-spectrometry allows the rapid measurement of relatively low-activity samples without complex analytical preparations. A technique described by Michel et al. [25] uses Ge(Li) /-ray detectors for the simultaneous measurements of 228radium and 226radium in natural waters. This method simplifies the analytical procedures and reduces the labour while improving the precision, accuracy, and detection limits. 

The hydride generation technique is a technique in which volatile metal hydrides are formed by chemical reaction of the analyte solutions with sodium borohydride. The hydrides are guided to the path of the light, heated to relatively low temperatures, and atomized. It is useful because it provides an improved method for arsenic, bismuth, germanium, lead, antimony, selenium, tin, and tellurium. 

Three analytical tools were used to characterize the compounds. The first is powder x-ray diffraction methods using a 114.6-mm. diameter camera. The photographs were in general poor for germanium telluride and, as a result, the parameters were determined from low-angle reflections only. The second procedure involved room temperature Seebeck coefficient data (taken versus copper and converted to absolute values) which qualitatively vary inversely as the log of the carrier concentration. Finally, Hall measurements were taken on 1.6 X 0.5 X 0.1 cm. plates in a manner already described (6). 

The availability of high flux thermal neutron irradiation facilities and high resolution intrinsic Ge and lithium drifted germanium (Ge(Li)) or silicon (Si(Li)) detectors has made neutron activation a very attractive tool for determining trace elemental composition of petroleum and petroleum products. This analytical technique is generally referred to as instrumental neutron activation analysis (INAA) to distinguish it from neutron activation followed by radiochemical separations. INAA can be used as a multi-elemental method with high sensitivity for many trace elements (Table 3.IV), and it has been applied to various petroleum materials in recent years (45-55). In some instances as many as 30 trace elements have been identified and measured in crude oils by this technique (56, 57). 

C. Remigius Fresenius once again deserves credit for noting, toward the middle of the nineteenth century, that new analytical techniques invariably lead to fresh sets of discoveries. Whereas the element germanium was found on the basis of "classical methods (Clemens Winkler, 1886), Fresenius observation clearly applies to the discovery of the alkali metals rubidium and cesium (by Robert W. Bunsen after he and G. R. Kirch-HOFF first developed emission spectroscopy in 1861). Other relevant examples include the discoveries of radium and polonium (by Madame Curie), hafnium (Hevesy and Coster, 1922), and rhenium (1. Tacke and W. Noddack, 1925), all with the aid of newly introduced X-ray spec-trometric techniques. This is also an appropriate point to mention the discovery of nuclear fission by Otto Hahn and Fritz Strassmann (19. 8), another accomplishment with strongly analytical characteristics 110]. 

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