Rubidium species

Acyclic semidiones (RC(0)=C(0 ) R) and their metal complexes exhibit rapid E — Z equilibration where the ElZ ratio is determined by the extent of ion pairing. The ElZ ratio changes directly with the alkali metal cation radius or the solvent dielectric constant. Both K+ and Rb+ dimethylsemidione prefer the ( )-conformation. The free energy of the ( ) rubidium species is lower by ca 2 kJmoH than that of the potassium species. As the size of the R group increases, the proportion of E increases . In DMSO in the presence of potassium ion, the ( )-dimethylsemidione is more stable than the (Z)-isomer by 10.5 kJmoH. For comparison, dimethylethylene (i.e. 2-butene) is more stable as the ( )-form by 4.3 kJmoH. ... 

Most modeling programs have a selection of 30 to 80 or more basis species, plus a collection of minerals and gases, from which the modeler chooses those required to describe the composition of all aqueous species, gases, and minerals in a particular system. If an element, say rubidium (Rb), does not occur as a basis species (as say, Rb+) in the database, the program is of course then unable to calculate the amounts of various rubidium species or minerals, even if we have an analysis for the rubidium content of our system. 

Illite is the most dominant mineral present in soil samples. Apart from this mineral even smectite, kaolite, and chlorite will be present in the soil. Illite absorbs, in practice, some potassium, ammonium, cesium, and rubidium species. The solubility of clay mineral is quite high under acidic (pH <4) environmental conditions. 

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],... 

This has led to such cases in the history of chemistry that spectroscopic signals have been unidentified till newly discovered elements was found (e.g. rubidium, caesium, indium, helium, rhenium) or new species (highly ionized atoms, e.g. in northern lights [aura borealis], luminous phenomena in cosmic space and sun aura, such as nebulium , coronium , geocoronium , asterium , which was characterized at first to be new elements see Bowen [1927] Grotrian [1928] Rabinowitsch [1928]). 

It should not be inferred that the crystal structures described so far apply to only binary compounds. Either the cation or anion may be a polyatomic species. For example, many ammonium compounds have crystal structures that are identical to those of the corresponding rubidium or potassium compounds because the radius NH4+ ion (148 pm) is similar to that of K+ (133 pm) or Rb+ (148 pm). Both NO j and CO, have ionic radii (189 and 185 pm, respectively) that are very close to that of Cl- (181 pm), so many nitrates and carbonates have structures identical to the corresponding chloride compounds. Keep in mind that the structures shown so far are general types that are not necessarily restricted to binary compounds or the compounds from which they are named. 

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. 

Figures 1 through 5 should, therefore, be considered as representative values which (especially at values of Cj less than 10 mg-atom/ml) might be subject to variations on the order of 0.5 log units. Furthermore, the assumption that the solid-phase concentrations of rubidium, strontium and barium given in Table I represented the concentrations of sorbed species introduces further...

This paper presents the more important data and conclusions from three reports which describe the uptake behavior of the vaporized oxides of molybdenum, tellurium, and rubidium by molten and solid substrates at high temperatures (I, 2, 3). These oxides were used as the vapor species because of their relatively high volatility and because of their importance as radioactive constituents, or the precursors of important constituents, of radioactive fallout particles. 

Figures 6 and 7 show the uptake of rubidium oxide vapor by various sized particles of clay loam and calcium ferrite at 1400°C. There is uncertainty as to the molecular species found in rubidium oxide vapor under the experimental conditions. Data furnished by Bedford and Jackson indicate that the vapor should consist of a mixture of RbO and Rb molecules with RbO predominating (4). Experimental work by Norman and Staley indicate that the vapor should consist predominately of Rb with minor amounts of Rt O molecules (13). To calculate vapor pressures it was assumed that the vapor consisted only of RbO. Since the molecular weight of Rb is only 16% less than that of RbO, no large error is introduced by this assumption even if the vapor consists of Rb molecules.

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.

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