Rubidium absorption

Rubidium metal is commeicially available in essentially two grades, 99 + % and 99.9 + %. The main impurities ate other alkali metals. Rubidium compounds are available in a variety of grades from 99% to 99.99 + %. Manufacturers and suppliers of mbidium metal and mbidium compounds usually supply a complete certificate of analysis upon request. Analyses of metal impurities in mbidium compounds are determined by atomic absorption or inductive coupled plasma spectroscopy (icp). Other metallic impurities, such as sodium and potassium, are determined by atomic absorption or emission spectrograph. For analysis, mbidium metal is converted to a compound such as mbidium chloride. 

In the 1859 the chemist Robert Wilhelm Bunsen and his younger colleague, the physicist Gustav Kirchhoff, discovered a surprising phenomenon of spectroscopy. The emission and absorption spectra of an element are identical. They thus put into place an ideal tool for the discovery and identification of elements. Indeed, they themselves discovered cesium (1860) and rubidium (1861). In total, at least 20 elements were found by using spectroscopic technigues (including X-ray spectroscopy). 

Shen and Ii [149] extracted caesium (and rubidium) from brine samples with 4-tert-butyl-2-(a methyl-benzyl) phenol prior to atomic absorption spec-trometric determination of the metal. 

Nixon277 compared atomic absorption spectroscopy, flame photometry, mass spectroscopy, and neutron activation analysis as methods for the determination of some 21 trace elements (<100 ppm) in hard dental tissue and dental plaque silver, aluminum, arsenic, gold, barium, chromium, copper, fluoride, iron, lithium, manganese, molybdenum, nickel, lead, rubidium, antimony, selenium, tin, strontium, vanadium, and zinc. Brunelle 278) also described procedures for the determination of about 20 elements in soil using a combination of atomic absorption spectroscopy and neutron activation analysis. 

The method, also called heavy atom method, consists in introducing a heavy atom in the molecule. Then X-rays with a wave length close to the X-ray absorption of the heavy atom is introduced. As a result a phase shift is superimposed on the ordinary diffraction pattern and configuration is then deduced. The method was first employed in 1951 by Bijvoet et al. to examine sodium rubidium tartrate who concluded that it is possible to differentiate between the two optically active forms. In other words it was possible to determine the absolute configuration of the enantiomers. Since then the absolute configurations of about two hundred optically active compounds have been elucidated by their correlation with other substances of known configuration. 

Example The intensity of atomic absorption lines for the alkali metals, such as potassium (K) rubidium (Rb) and caesium (Cs), is found to be affected by temperature in a complex way. Under certain experimental parameters a noticeable decrease in absorption may be observed in hotter flames. Hence, lower excitation temperatures are invariably recommended for the analysis of alkali metals. 

Hydrogenation of dibenzofuran over a platinum catalyst in acetic acid at 50°C and moderate pressure affords perhydrodibenzofuran. At higher temperatures and pressures with platinum or palladium catalysts the product is 2-biphenylol. When dibenzofuran is hydrogenated in ethanol over Raney nickel at 190°C and 200 atm for 23 h, the products isolated were perhydrodibenzofuran (36%), trans-2-cyclohexylcyclohexanol (27%), cis-2-cyclohexylcyclohexanol (20%), and dicyclohexyl (3%). When the hydrogenation, under these conditions, was terminated after the absorption of only 3 mol equiv of hydrogen, the only product detected was perhydrodibenzo-furan. ° Hydrogenation of dibenzofuran over a sodium-rubidium catalyst,... 

German physicist and physical chemist. Professor of physics at Heidelberg and Berlin. Independent discoverer of the Kirchhoff-Stewart law of radiation and absorption. He explained the Fraunhofer lines of the solar spectrum, and, with Bunsen, founded the science of spectroscopic analysis and discovered the elements cesium and rubidium. 

Also called vapour-phase interferences or cation enhancement. In the air-acetylene flame, the intensity of rubidium absorption can be doubled by the addition of potassium. This is caused by ionization suppression (see Section 2.2.3), but if uncorrected will lead to substantial positive errors when the samples contain easily ionized elements and the standards do not. An example is when river water containing varying levels of sodium is to be analysed for a lithium tracer, and the standards, containing pure lithium chloride solutions, do not contain any ionization suppressor. 

Properties oi the alkali hydroxides.—The alkali hydroxides are brittle, white, translucent solids with a more or less crystalline fracture, and fibrous texture. Sodium hydroxide deliquesces on exposure to the air, but it goes solid again owing to the formation of the carbonate by the absorption of carbon dioxide from the air. Lithium hydroxide is a little hygroscopic. Potassium hydroxide is even more deliquescent than the sodium compound but its carbonate is also deliquescent. The hydroxides are very solnble in water, and they also dissolve in alcohol. The reported numbers for the specific gravities22 of sodium hydroxide range from l-723 to 2T30 and for potassium hydroxide, from l-958 to 2 6. The best representative sp. gr. are 2"54 for lithium hydroxide 2130 for sodium hydroxide 2 044 for potassium hydroxide 3"203 (11°) for rubidium hydroxide and 3-675 (11°) for csesium hydroxide. 

One of the ways we will learn to express quantities in Chapter 1 is by using prefixes such as mega for million (I06), micro for one-millionth (10-6). and atto for 10-18. The illustration shows a signal due to light absorption by just 60 atoms of rubidium in the cross-sectional area of a laser beam. There are 6.02 X 1023 atoms in a mole, so 60 atoms amount to 1.0 X 10-22 moles. With prefixes from Table 1-3, we will express this number as 100 yoctomoles (ymol) or 0.1 zeptomole (zmol). The prefix yocto stands for I0-24 and zepto stands for 10-21. As chemists learn to measure fewer and fewer atoms or molecules, these strange-sounding prefixes become more and more common in the chemical literature. 

Atomic absorption signal from 60 gaseous rubidium atoms observed by laser wave mixing. A 10-microliter (10 x 10 6 L) sample containing 1 attogiam (1 x 10-18 g) of Rb was injected into a graphite furnace to create the atomic vapor. We will study atomic absorption spectroscopy in Chapter 21. [R K. Mickadelt,... 

Ethylamine Solutions, (a) Photoregeneration of Bleached Solutions—The absorption spectra of alkali metals in ethylamine have been discussed in previous publications (24,25). Briefly, three characteristic bands are found, absorbing at about 650 (V), 850 (R) and 1300 (IR) m/z, and attributed respectively to metal monomers, dimers, and solvated electrons. In potassium solutions, the equilibria favor the V-band, while in rubidium the R-band is most prominent, except at extreme dilutions. 

Fig. 14. Electron spin resonance spectrum of a frozen solution of rubidium in HMPA, at high machine amplification. The full lines show the variation of resonant field position with A for ge = 1.99800, and a microwave frequency of 9.1735 GHz. The lines are anchored at the crossovers of the MG species (A = 251.3 G). Positions of the Mc, M , ME, Mg, Mh, and M, absorptions are indicated. Reprinted with permission from R. Catterall and P. P. Edwards, Journal of Physical Chemistry, 79, 3010 (1975). Copyright 1975 American Chemical Society.

Fig. 17. Optical spectra of lithium, sodium, potassium, rubidium, and cesium in ethylenediamine with identification of absorption peaks of Na, K, Rb, Cs and er. Absorption for es is taken from pulse radiolysis studies. [Taken from Fig. 1 of Dye (57) used with permission of Verlag-Chemie, Angew. Chem.Int. Ed. Engl.]...

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