Potassium optical spectra

Spectral Gamma Ray Log. This log makes use of a very efficient tool that records the individual response to the different radioactive minerals. These minerals include potassium-40 and the elements in the uranium family as well as those in the thorium family. The GR spectrum emitted by each element is made up of easily identifiable lines. As the result of the Compton effect, the counter records a continuous spectrum. The presence of potassium, uranium and thorium can be quantitatively evaluated only with the help of a computer that calculates in real time the amounts present. The counter consists of a crystal optically coupled to a photomultiplier. The radiation level is measured in several energy windows. 

Potassium borohydride reduction of runanine (17) yielded dihydro-runanine (24), the H-NMR spectrum of which (Table II) exhibited a triplet (64.25), the proton bearing the hydroxyl group coupling with those of C-5 (35). The optical activity of runanine (17), [a]D —400°, was similar to that of hasubanonine (5), [a]D —214° (3) therefore, it was concluded that the ethylamine linkage must have the same configuration as hasubanonine [C-13 (R) and C-14 (S)]. From these results, structure 17 was proposed for runanine (35) however, no application of mass spectral data to the structure elucidation was presented (35). 

Currently used nonlinear optical crystals are potassium dihydrogen phosphate (KDP) and barium borate (BBO). Compared to KDP, the advantages of BBO are its transparency in the UV and its larger quantum efficiency of up-conversion by a factor of 4—6. For a given position of the crystal, only a narrow band of the fluorescence spectrum is up-converted. Therefore, if the full fluorescence spectrum is of interest, the crystal must be rotated at a series of angles. An example of experimental set-up is presented in Figure 11.2. The fwhm of the response is 210 fs. 

Many elements are present in the earth s crust in such minute amounts that they could never have been discovered by ordinary methods of mineral analysis. In 1859, however, Kirchhoff and Bunsen invented the spectroscope, an optical instrument consisting of a collimator, or metal tube fitted at one end with a lens and closed at the other except for a slit, at the focus of the lens, to admit light from the incandescent substance to be examined, a turntable containing a prism mounted to receive and separate the parallel rays from the lens and a telescope to observe the spectrum produced by the prism. With this instrument they soon discovered two new metals, cesium and rubidium, which they classified with sodium and potassium, which had been previously discovered by Davy, and lithium, which was added to the list of elements by Arfwedson. The spectroscopic discovery of thallium by Sir William Crookes and its prompt confirmation by C.-A. Lamy soon followed. In 1863 F. Reich and H. T. Richter of the Freiberg School of Mines discovered a very rare element in zmc blende, and named it indium because of its brilliant line in the indigo region of the spectrum. 

M. le Blanc gave the refractive indices of solii. of potassium and rubidium bromides as 1 5593 and 1 5533 respectively, when the densities are 2"738 and 3 314 respectively. Hence the refraction eq. of potassium bromide by Gladstone and Dale s formula is therefore 24 32 and by Lorentz and Lorenz s formula 14-05 the corresponding values for rubidium bromide are27"62 and 15"98. The mol. refractions of potassium bromide in soln. by the two formulae are respectively 25"11 and 14 70 and of rubidium bromide in soln., 27 85 and 16 33. The mol. refractions of these salts are therefore greater in soln. than in the solid form. Crystals of potassium bromide, says H. Marbuch, exhibit optical activity. A. S. Newcomer found that sodium chloride was the only salt relatively soluble and yet capable of emitting fluorescent rays in the mid-ultra-violet region of the spectrum under the influence of X-rays. 

Properties of Potassium Hexafluoroplatinately).—This salt is mustard yellow. A sample containing some iodine, possibly as iodyl fluoride, was paramagnetic. The low value of the magnetic moment, p = 0-87 B.M. (at 23°), may, in part at least, be due to this impurity. An infrared spectrum, of a Nujol mull, recorded with sodium chloride and cmsium bromide optics, showed two broad, overlapping, absorption bands, with peaks at 590 and 640 cm.. X-Ray powder photographs of the salt have been indexed on the basis of a rhombohedral unit-cell, a = 4-96 A, a = 97-4°, U = 119 9 A. The observed and calculated values for 1/df are given in Table 5. The solid can be stored indefinitely in well-dried, sealed tubes but decomposes... 

Figure 4.4 Vis-NIR optical absorption spectra of the six anionic redox stages of [(THPP)Zn] in THF taken at room temperature, obtained by reduction with potassium. The spectra are shown for the visible to NIR region from 480 to 1400nm since the Soret region is far too intense. Acquisition time was 230 s per spectrum. With permission from Elsevier, ref. 5.

A complication in these reactions is the similar properties for trans dimer 6 and the cis dimer 20. The only noticeable difference in the NMR spectrum is the shift of one H resonance by 0.01 ppm, and a shift in the pyrazine l3C resonances by about 0.1 ppm, while the optical rotations are identical ([a]D = +82°). However, the compounds have very different solubilities - trituration of the mixture with ethanol yields the trans dimer upon filtration, while the crude cis dimer is obtained by evaporation of the filtrate. This separation procedure enabled purification of the mixture obtained from reaction of 2ot,3a-diaminocholestane (obtained by borane reduction of 22) and 2,3-diketocholestane (obtained by oxidation of 3-cholestanone with potassium t-butoxide and oxygen) (Figure 11). 

The heteropoly anions PV2Moio0 o and PV WioOj o are each shown to exist as mixtures of the five possible stereoisomers by P NMR spectroscopy. Controlled potential electrolytic reduction of HsPV ioOi o yields PV W Wio-(I) and PV2 Wio0 o (II) which were isolated as potassium salts. The ESR spectrum of anion I consists of superimposed 8- and 15-line components with (g) = 1.952 and (a) = 104.5 and 53 G. The relative intensities of the 8- and 15-line spectra are in quantitative agreement with the assumption that electron exchange between neighboring vanadium atoms (V-O-V) is rapid, but that in isomers with remote vanadium atoms (V-O-W-O-V, etc.) the electron is effectively trapped on a single vanadium. The ESR spectrum of anion II has a normal 15-line pattern arising from the triplet state. The intervalence optical transition in anion I occurs at 8.8 kK. 

The chemistry can be illustrated with the case of adenine isodideoxynucleoside. The key precursor for the coupling reaction was compound 14 (Scheme 7), which can be synthesized in excellent yields (17%) from D-xylose. Condensation of 14 with adenine stereospecifically and regiospecifically was carried out by reaction with this base in the presence of potassium carbonate and 18-crown-6 in DMF. Deprotection of the resulting product with sodium methoxide in methanol gave the target isodideoxynucleoside 15 in 55% yield (for the last two steps). The structure of 15 was confirmed by its UV spectrum (260 nm, e 14,000), H and C NMR data (single compound and absence of astereoisomer), and optical rotation ([a]p = -26.6°). TTiis magnitude of levorotation is the... 

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