Rubidium emission from

FIGURE 9-17. Rubidium emission signals (7800 A) in the presence of potassium. [From W. G. Schrenk, in Flame Emission and Atomic Absorption Spectroscopy. Vol. 2, Edited by J. A. Dean and T. C. Rains, Marcel Dekker, New York (1971), Chapter 12. Used by permission of Marcel Dekker Inc.]... 

Thermionic emission Electron emission from a heated surface. This term is a misnomer since generally few ions are emitted from a heated surface for most materials. Exceptions are fluorine, cesium, potassium, and rubidium, which can be ionized by evaporation from a heated surface. See also Thermoelectronic emission. 

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. 

The blue satellite peak associated with resonance line of rubidium (Rb) saturated with a noble gas was closely examined by Lepoint-Mullie et al. [10] They observed SL from RbCl aqueous solution and from a 1-octanol solution of rubidium 1-octanolate saturated with argon or krypton at a frequency of 20 kHz. Figure 13.4 shows the comparison of the SL spectra of the satellite peaks of Rb-Ar and Rb-Kr in water (Fig. 13.4b) and in 1-octanol (Fig. 13.4c) with the gas-phase fluorescence spectra (Fig. 13.4a) associated with the B —> X transition of Rb-Ar and Rb-Kr van der Waals molecules. The positions of the blue satellite peaks obtained in SL experiments, as indicated by arrows, exactly correspond to those obtained in the gas-phase fluorescence experiments. Lepoint-Mullie et al. attributed the blue satellites to B — X transitions of alkali-metal/rare-gas van der Waals species, which suggested that alkali-metal atom emission occurs inside cavitating bubbles. They estimated the intracavity relative density to be 18 from the shift of the resonance line by a similar procedure to that adopted by Sehgal et al. [14],... 

As shown in Table 11.1, hydrothermal emissions are a major source of soluble iron, manganese, and zinc and a minor source of aluminum, cobalt, copper, and lead. Other elements with significant hydrothermal inputs include lithium, rubidium, cesium, and potassium. Considerable uncertainty also surroimds these flux estimates because they are the result of extrapolations from measurements made at a small number of hydrothermal systems at single points in time. These fluxes appear to vary significantly over short time scales as tectonic activity abruptly opens and closes cracks in the oceanic crust. 

The principal rubidium salts which would probably have been present in the sediment (chloride, sulfate, bicarbonate, etc.) are all soluble in water. As discussed later, the red clay was thoroughly dialyzed prior to use (including prior to analysis by emission spectroscopy). Any rubidium salts initially present in the clay samples would, therefore, have been removed by the dialyzing solution. Hence, it was assumed that the rubidium concentration given in Table I represented sorbed rubidium which had been in equilibrium with the rubidium in the original interstitial seawater. Then when calculating distribution coefficients from experimental data, the concentration given in Table I was used as the initial clay-phase rubidium concentration, rather than zero as used with most of the other species studied. 

Fair Lawn, NJ 07410) prepared from the metal (Mg, Ni, Mn, Mo, Co), the oxide (Cu, Cr), the chloride (Fe), or the carbonate (Sr) and contain dilute HC1, HNO3, or aqua regia as the solvent. For the emission studies, all solutions were prepared to contain 1000 mg/ , rubidium to reduce interelement effects observed for alkali and... 

Potassium and sodium were first isolated within a few days of each other in 1807 by Humphry Davy as products of the electrolysis of molten KOH and NaOH. In 1817, J. A. Arfvedson, a young chemist working with J. J. Berzelius, recognized similarities between the solubilities of compounds of lithium and those of sodium and potassium. The following year, Davy also became the first to isolate lithium, this time by electrolysis of molten Li20. Cesium and rubidium were discovered with the help of the spectroscope in 1860 and 1861, respectively they were named after the colors of the most prominent emission lines (Latin, caesius, sky blue, rubidus, deep red). Francium was not identified until 1939 as a short-lived radioactive isotope from the nuclear decay of actinium. 

The history of atomic emission spectrometry (AES) goes back to Bunsen and Kirchhoff, who reported in 1860 on spectroscopic investigations of the alkali and alkali earth elements with the aid of their spectroscope [1], The elements cesium and rubidium and later on thorium and indium were also discovered on the basis of their atomic emission spectra. From these early beginnings qualitative and quantitative aspects of atomic spectrometry were considered. The occurrence of atomic spectral lines was understood as uniequivocal proof of the presence of these elements in a mixture. Bunsen and Kirchhoff in addition, however, also estimated the amounts of sodium that had to be brought into the flame to give a detectable line emission and therewith gave the basis for quantitative analyses and trace determinations with atomic spectrometry. 

The prevailing values of HM emission (more than 650 tons per year) were found to be for Barium and Strontium in 1990, i.e., at the peak of lignite use for power generation in the country. In this year, the emissions of Vanadium, Rubidium, and Arsenic were found to be in the range between 120 and 202 tons. Relatively small emissions were calculated to be for Cesium, Chromium, Nickel, Cerium and Lanthanum (25-63 tons per year). The smallest emissions were found to be for Uranium, Thorium, and Antimony, the value of which lay within the range from 6 to 8 tons per year. 

Atom-ion equilibria in flames create a number of important consequences in flame spectroscopy, b or example, intensities ol atomic emission or absorption lines for the alkali metals, particularly potassium, rubidium, and cesium, are affected by leniperalure in a complex way. Increased temperature cause an increase in the population of excited atoms, according lo the Boltzmann relationship (Kqualion S-l). Counteracting this effect, however, is a decrease in concentration of atoms resulting from ionization. Thus, under some circumstances a decrease in emission or abst>rp-lion may be observed in hotter flames. It is or this reason that lower e.xciialion Icmperaliircs are usually spcciliod for the deierminaiion of alkali metals. 

Two elements, caesium and rubidium, were discovered by Robert Bunsen in 1860 and 1861 after studying atomic emission spectra of this type. They are named after the presence of a pair of brightly coloured lines in their spectra—caesium from the Latin caesius meaning bluish grey and rubidium from the Latin rubidus meaning red. 

FIGURE 9-11. Effect of potassium on the flame emission intensity of rubidium. [From T. E. Shellenberger, R. E. Pyke, D. B. Parrish, and W. G. Schrenk, Some Factors Affecting the Flame Photometric Emission of Rubidium in an Oxy-Acetylene Flame, AnaL Chem., 32, 210 (1960). Used by permission of the American Chemical Society.]... 

The popularity of the BCD can be attributed to the high sensitivity to organohalogen compounds, which include many compounds of environmental interest, including polychlorinated biphenyls and pesticides. It is the least selective of the so-called selective detectors but has the highest sensitivity of any contemporary detector. The NPD or thermionic ionization or emission detector is a modified FID in which a constant supply of an alkali metal salt, such as rubidium chloride, is introduced into the flame. It is a detector of choice for analysis of organophosphorus pesticides and pharmaceuticals. The FPD detects specific luminescent emission originating from various excited state species produced in a flame by sulfur- and phosphorus-containing compounds. 

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