Rb Salts Research Articles

The uptake and extrusion of salts by the halotolerant bacterium, Ba 1

Ion fluxes were studied in the cells of the moderately halophilic, halotolerant bacterium, Ba 1. K + and Rb + ions rapidly penetrated the cell membrane in contrast to Na + and Li + ions which were found to be nearly nonpenetrant. Moreover, Na + ions at millimolar concentrations inhibited the passive penetration of K + and Rb + into the cytosol. Under energized conditions a powerful pump mechanism became functional causing extrusion of the penetrated K or Rb salt, as revealed by light-scattering changes as well as by tracer methods. From the pattern of action of agents which are known to interfere with respiration or energy transformation it was concluded that this pump is activated by the electrochemcial proton gradient without the mediation of ATP. In the range of pH values between 7.0 and 8.0 the rate of respiration and that of the extrusion of the salt declined gradually and in a near-parallel manner. The presence of Na + ions at low concentrations prevented this drop in the two activities. Some evidence is brought in favor of the view that the pump activity is controlling respiratory rate rather than vice versa. It is suggested that the pump responsible for the extrusion of the K salt may be involved in the regulation of the intracellular salt concentration and, as a corollary, in the mechanism of adaptation of Ba 1 to variation in the salinity of the environment.

The Influence of Pretreatment of Barley Plants with K+ and Cl− Ions on Subsequent Upward Transport of Absorbed Na+ Ions

Summary The effect of pretreating barley plants with K or Rb salts on the time course of upward translocation of absorbed Na + ions was studied. It appeared that the moment at which Na + ions entered the shoots, was advanced when the plants had previously absorbed K + together with Cl − . No forward shift of the start of upward Na+ transport was observed when the plants were pretreated with a solution of K 2 SO 4 or RbCl. The effect appeared to depend on the lenght of the period during which KC1 had been absorbed rather than on the total amount of KCl taken up within this period. The results are discussed in relation to the transport process in the symplast.

Solid state vibrational spectroscopy. 9—A kinetic study, using Raman spectroscopy, of the solid state thermal decompositions of alkali metal peroxydisulphates

AbstractThe kinetic behaviour of the solid state thermal decomposition of peroxydisulphate to pyrosulphate, M2[S2O8] → M2[S2O7], M = Na, K, Rb, Cs, has been studied by following the temporal decrease in the intensity of the Raman band arising from the vs(SO3) mode of [S2O8]2−. The data are best analysed using a conventional kinetic approach rather than the Avrami–Erofeev treatment normally applied to solid state reactions. Although the salts display different kinetic orders, 1.5, 2.0, 1.0 and 1.0 for the Na, K, Rb and Cs salts respectively, the lack of crystallographic data does not allow us to rationalize these differences.

Kinetic analysis of thermogravimetric data. XI thermal decomposition of some metal dithionates

A thermal analytical study of Li, Na, K, Rb, Cs, NH4, Mg, Ca, Sr, Ba and Zn dithionates is reported. The decomposition of the dithionate ion is endothermic in the case of the Na, K, Rb, Cs and NH4 salts, but exothermic with Li, Mg, Sr, Ba and Zn. Kinetic parameters have been derived from the TG curves by means of the Coats-Redfern method. The validity of a linear kinetic compensation law is reported for the loss of crystal water and separately for the decomposition of the dithionate ion.

Structural evidence for xenon-chlorine bonding: neutron and x-ray diffraction determinations of the structure of cesium and rubidium trioxodichloroxenate(VI) chloride, Cs9(XeO3Cl2)4Cl and Rb9(XeO3Cl2)4Cl

The compounds XeO/sub 3/ . 2.25 CsCl and XeO/sub 3/ . 2.25 RbCl have been structurally characterized as cesium and rubidium trioxodichloroxenate(VI) chloride, M/sub 9/(XeO/sub 3/Cl/sub 2/)/sub 4/Cl, using single-crystal counter diffraction methods. The crystals are body-centered tetragonal, point group 4/m, with a = 16.56 A and c = 7.10 A for the Cs salt and a = 15.97 A and c = 6.91 A for the Rb salt, and contain eight XeO/sub 3/ . 2.25 MCl formula units per unit cell. The structures have been refined in the space group I anti 4 to R factors of 8.3% for the Cs compound using neutron data and 10.4% for the Rb compound using x-ray data. The crystal structures contain infinite chains, parallel to c, of XeO/sub 3/Cl/sup -/ units linked by nearly linear chlorine bridges. The metal cations and one-ninth of the chlorine atoms are separated from the repeating polymeric unit XeO/sub 3/Cl/sub 2//sup 2 -/ by nonbonding distances. The xenon coordination is octahedral (distorted) with three terminal oxygen neighbors (in the Cs salt) at 1.77 A, one terminal Cl neighbor at 2.96 A, and two bridging Cl neighbors at 2.95 and 2.97 A.

Magneto-optical investigation of the linear chain ferromagnets AFeCl3(A=K,Rb,Cs)

The optical absorption and dichroism spectra are reported from 3000 to 300 nm from 1.2 to 300K in parallel and transverse fields up to 5T. The quintet-triplet transitions are assigned in the approximation of an octahedral crystal field and the origin of the broad polarised band at about 540 nm in the Rb and Cs salts is discussed. The temperature dependence of the spin-forbidden transitions enhanced by the exchange-induced electric dipole mechanism is analysed using the classical spin model of Ebara and Tanabe (1974). At the lowest temperatures the observed intensities deviate significantly from the theoretical predictions and do not approach zero. Evidence is presented that this is due to large zero-point fluctuations of the spin system rather than the perturbing influence of the groundstate orbital angular momentum.

Electrical Conductivity of Single Crystals of N-Methylphenazinium–TCNQ and Rb–TCNQ

Abstract Temperature and pressure dependence of the electrical conductivity of NMP(I)–, NMP(II)–, Rb(I)– and Rb(II)–TCNQ single crystals was studied. NMP(I)–TCNQ showing diffuse streaks was found to have a semiconductive behavior at atmospheric pressure and no conductive maximum appeared at low temperatures. Moreover the metallic behavior was not shown even at 100 kbar. The crystal structure of NMP(II)–TCNQ is not similar to that of NMP(I)–TCNQ. The difference of physical properties of two phases is discussed. The anomalous electrical behavior in the pressure range from 1 bar to 40 kbar was observed for Rb(I)–TCNQ. The resistivity of Rb(II)–TCNQ decreased monotonously with increasing pressure. The magnitude of their activation energies was 0.15 eV for Rb(I) salt and 0.11 eV for Rb(II) salt at 100 kbar. The insulator to metal transition could not be observed at least up to 100 kbar.

ChemInform Abstract: PULSED NMR STUDIES OF FLUORINE RELAXATION IN MPF6

AbstractDie Spin‐Gitter‐Relaxationszeit von Fluor in polykristallinem MPFÖ (M: Na, K, Rb, Cs) bei Temperaturen zwischen 77 und 476°K wird untersucht.

Gand Hyperfine Components ofVKCenters

Experimental values of the $g$ and hyperfine components of ${{X}_{2}}^{\ensuremath{-}}\ensuremath{-}{V}_{K}$ centers and ${{Y}_{2}}^{\ensuremath{-}}\ensuremath{-}{V}_{K}$-type centers ($X, Y=\mathrm{F},\phantom{\rule{0ex}{0ex}}\mathrm{C}\mathrm{l},\phantom{\rule{0ex}{0ex}}\mathrm{B}\mathrm{r},\phantom{\rule{0ex}{0ex}}\mathrm{I}$) in a large number of pure ($\mathrm{AX}$) and doped ($AX:{Y}^{\ensuremath{-}}$) alkali halides have been determined through a careful analysis of their electron-paramagnetic-resonance (EPR) spectra. Expressions for the $g$ components have been derived. For an accurate quantitative analysis, it is necessary to take into account the overlap terms in the calculation of $\ensuremath{\delta}$, the matrix element of the orbital angular momentum $\stackrel{\ensuremath{\rightarrow}}{1}$ between the $^{2}\ensuremath{\Sigma}_{u}^{+}$ ground state and the $^{2}\ensuremath{\Pi}_{u}$ state. A calculation for ${\mathrm{Cl}}_{2}^{\ensuremath{-}}$ yields $\ensuremath{\delta}=0.78$. Representative experimental values for ${\mathrm{Cl}}_{2}^{\ensuremath{-}}$ and ${\mathrm{Br}}_{2}^{\ensuremath{-}}$ are $\ensuremath{\delta}=0.73 \mathrm{and} 0.70$, respectively. The $^{2}\ensuremath{\Sigma}_{u}^{+}\ensuremath{-}^{2}\ensuremath{\Pi}_{u}$ energy differences thus determined decrease going from the Rb salt to the Li salt. This behavior, in general, parallels that of the $^{2}\ensuremath{\Sigma}_{u}^{+}\ensuremath{-}^{2}\ensuremath{\Sigma}_{g}^{+}$ and $^{2}\ensuremath{\Sigma}_{u}^{+}\ensuremath{-}^{2}\ensuremath{\Pi}_{g}$ energy differences which are known from the optical-absorption measurements. The crystal field splitting of the $^{2}\ensuremath{\Pi}_{u}$ state is determined from the orthorhombic character of the $g$ tensor. Expressions for the hyperfine components have been derived which include the first- and second-order correction terms originating from the combined effect of the spin-orbit and hyperfine operators. From the analysis of the combined behavior of the orthorhombic character of the $g$ and hyperfine (hf) components, it can be concluded that ${A}_{\ensuremath{\parallel}}g0$ and ${A}_{\ensuremath{\perp}}g0$ for ${\mathrm{Cl}}_{2}^{\ensuremath{-}}$, ${\mathrm{Br}}_{2}^{\ensuremath{-}}$, and ${\mathrm{I}}_{2}^{\ensuremath{-}}$, and ${A}_{\ensuremath{\parallel}}g0$ and ${A}_{\ensuremath{\perp}}l0$ for ${\mathrm{F}}_{2}^{\ensuremath{-}}$. The analysis of the hf components then shows that the isotropic part of the hf interaction decreases monotonically going from the Rb to the Li salt, while the anisotropic part remains approximately constant. EPR results for ${V}_{\mathrm{KA}}$, ${V}_{\mathrm{KAA}}$, and ${V}_{F}$ centers are also given and they are compared with the ${V}_{K}$-center data.

Pulsed NMR studies of fluorine relaxation in MPF6

The fluorine spin-lattice relaxation time T1 was studied in polycrystalline Na, K, Rb, and Cs hexafluorophosphates at temperatures between 77 and 476 °K by pulsed NMR methods. In each case a discontinuity occurs in the temperature dependence, at 276, 275, 210, and 82 °K, respectively; those for the K and Rb salts corresponding to previously reported phase transitions. The temperature dependence of T1 observed in the low-temperature phase of the Na, K, and Rb salts has a minimum and an asymmetric shape which are attributed to dipolar relaxation by thermally activated, random reorientations of the PF6− ions, the activation energy Ea being smaller on the low-temperature side of the T1 minimum than on the high side. The temperature of the T1 minimum and Ea decrease with increasing size of the cation, as does the transition temperature. The T1 's are very sensitive to the physical state of KPF6 and RbPF6 and to thermal cycling in RbPF6. Powering the sample broadens the T1 minimum, shifts it to lower temperatures by 2 to 8 °K, reduces its value by about 25%, and decreases the low-temperature Ea. These effects are analogous to those reported in earlier, line shape studies of MPF6 and are consistent with the two-phase model proposed in that connection. One phase consists of relatively perfect crystalline domains, with a high Ea, and the other of domains with defects which lower Ea. Spin exchange between the two types of domains is fast enough to average out the different T1 's in the two phases and produce exponential relaxation. However, in finely powdered RbPF6 at 77 °K, nonexponential relaxation was observed and is attributed to paramagnetic impurities. In the high-temperature phase of all four salts, T1 exhibits a broad frequency-independent maximum of 4–7 sec which is attributed to relaxation by spin-rotation interactions within the rapidly reorienting PF6− ions.

75As spin-lattice relaxation and resonance in KH2AsO4 type ferroelectric crystals

The temperature dependence of the 75As dipolar spin-lattice relaxation time in both para- and ferroelectric KH2AsO4 and CsH2AsO4 has been determined and the results are related to the microscopic model of the phase transition. The temperature dependences of 75As NQR frequency and linewidth in KD2AsO4 and CsD2AsO4 and the corresponding Rb salts have been as well studied and a good agreement has been found between the theoretical and experimental results.

Revision of lunar Rb-Sr ages

Becalibration of ‘spikes’ using stoichiometric Rb and Sr salts recently issued by the National Bureau of Standards shows that our determinations of the ratio 87Rb 86Sr in lunar samples have been low by 1.8 per cent, which we attribute to non-stoichiometry of the salts previously used for calibration, particularly RbCl. As a result, our lunar age-determinations must be decreased by this amount.

Gand Hyperfine Components ofVKCenters

Experimental values of the $g$ and hyperfine components of ${{X}_{2}}^{\ensuremath{-}}\ensuremath{-}{V}_{K}$ centers and ${{Y}_{2}}^{\ensuremath{-}}\ensuremath{-}{V}_{K}$-type centers ($X, Y=\mathrm{F},\phantom{\rule{0ex}{0ex}}\mathrm{C}\mathrm{l},\phantom{\rule{0ex}{0ex}}\mathrm{B}\mathrm{r},\phantom{\rule{0ex}{0ex}}\mathrm{I}$) in a large number of pure ($\mathrm{AX}$) and doped ($AX:{Y}^{\ensuremath{-}}$) alkali halides have been determined through a careful analysis of their electron-paramagnetic-resonance (EPR) spectra. Expressions for the $g$ components have been derived. For an accurate quantitative analysis, it is necessary to take into account the overlap terms in the calculation of $\ensuremath{\delta}$, the matrix element of the orbital angular momentum $\stackrel{\ensuremath{\rightarrow}}{1}$ between the $^{2}\ensuremath{\Sigma}_{u}^{+}$ ground state and the $^{2}\ensuremath{\Pi}_{u}$ state. A calculation for ${\mathrm{Cl}}_{2}^{\ensuremath{-}}$ yields $\ensuremath{\delta}=0.78$. Representative experimental values for ${\mathrm{Cl}}_{2}^{\ensuremath{-}}$ and ${\mathrm{Br}}_{2}^{\ensuremath{-}}$ are $\ensuremath{\delta}=0.73 \mathrm{and} 0.70$, respectively. The $^{2}\ensuremath{\Sigma}_{u}^{+}\ensuremath{-}^{2}\ensuremath{\Pi}_{u}$ energy differences thus determined decrease going from the Rb salt to the Li salt. This behavior, in general, parallels that of the $^{2}\ensuremath{\Sigma}_{u}^{+}\ensuremath{-}^{2}\ensuremath{\Sigma}_{g}^{+}$ and $^{2}\ensuremath{\Sigma}_{u}^{+}\ensuremath{-}^{2}\ensuremath{\Pi}_{g}$ energy differences which are known from the optical-absorption measurements. The crystal field splitting of the $^{2}\ensuremath{\Pi}_{u}$ state is determined from the orthorhombic character of the $g$ tensor. Expressions for the hyperfine components have been derived which include the first- and second-order correction terms originating from the combined effect of the spin-orbit and hyperfine operators. From the analysis of the combined behavior of the orthorhombic character of the $g$ and hyperfine (hf) components, it can be concluded that ${A}_{\ensuremath{\parallel}}>0$ and ${A}_{\ensuremath{\perp}}>0$ for ${\mathrm{Cl}}_{2}^{\ensuremath{-}}$, ${\mathrm{Br}}_{2}^{\ensuremath{-}}$, and ${\mathrm{I}}_{2}^{\ensuremath{-}}$, and ${A}_{\ensuremath{\parallel}}>0$ and ${A}_{\ensuremath{\perp}}<0$ for ${\mathrm{F}}_{2}^{\ensuremath{-}}$. The analysis of the hf components then shows that the isotropic part of the hf interaction decreases monotonically going from the Rb to the Li salt, while the anisotropic part remains approximately constant. EPR results for ${V}_{\mathrm{KA}}$, ${V}_{\mathrm{KAA}}$, and ${V}_{F}$ centers are also given and they are compared with the ${V}_{K}$-center data.

The formation of hydridopentacyanorhodate(III): a reappraisal of the formation of hydridoaquotetracyanorhodate(III)

The reaction of NaCN with [Rh(CO)2Cl]2 results in the formation of Na3RhH(CN)5. The anion has been isolated as the Na, K, Rb, and Cs salts. The 1H n.m.r., Raman, and i.r. spectra are reported for these compounds, and for the intermediates in the above reaction. Three long-lived solution species have been identified as Rh(CO)2(CN)Cl–, trans-Rh(CO)2(CN)2–, and Rh(CO)(CN)32– and the existence of at least two other intermediates may be inferred. The hydride previously formulated as K2Rh(CN)4(H)(H2O) is almost certainly K3Rh(CN)5(H),xH2O.

Influence of Dietary Potassium, Rubidium, or Sodium on the Retention Time of Radiocesium in Rats

SummaryIncreasing the K intake of rats above requirements reduced the half-retention time for 134Cs but at a decreasing rate. Maximum intake was 5% which resulted in T1/2 of 6 days. The Na added at 0.3 or 2% to high K diet had no influence on the T1/2 for 134Cs. The influence of Rb salts on 134Cs retention would indicate that this ion is less effective than K. The decreased effect of Rb may be due to its failure to adequately substitute for K in normal muscle cell metabolism.

The structures of cæsium and rubidium difluorophosphates

Crystals of caesium and rubidium difluorophosphates are orthorhombic, with a= 8·437, b= 6·796, c= 8·06 A for the Cs salt, and a= 8·15, b= 6·45, c= 7·79 A for the Rb salt, Z= 4, space-group Pnma. The structure of CsPO2F2 was determined by use of three-dimensional Mo-Kα scintillation counter data by comparison with potassium difluorophosphate, and refined by least-squares methods, the final R being 0·070 for 506 observed reflexions.Potassium, rubidium, and caesium difluorophosphates are isomorphous, and have the barium sulphate structure. The lattice parameters and interionic distances increase with increasing radius of the alkali-metal ion.

Growth and Metabolism of Chlorella pyrenoidosa

SUMMARYChlorella pyrenoidosa Chick, van Niel's strain, grown in a chemically defined medium, in which the potassium was replaced with rubidium, attained only 20%of the growth rate of algae in media containing K. Addition of sodium to K‐deficient media spared Rb uptake. Neither growth nor uptake of Rb were accelerated when glucose was added to media Cells which had been maintained on K‐free media, did not immediately respond to K, indicating that their metabolism had become adjusted to Rb. Free and combined amino acids, nonketo organic acids, polysaccharides, and chlorophylls were similar in K or Rb media. Fewer porphyrins, and in smaller quantity, were found in the cells grown in Rb media. Cells grown in K‐free media, analyzed by X‐ray fluorescence, showed 0.039%of their dry weight to be K contamination. When the K equivalent to the small contamination of the Rb salt was added to a Rb‐free medium, the cells failed to grow. The data indicate that Rb either can replace K entirely in cell metabolism, or that it can spare the K requirement. Substitution of K by Rb does not permit normal growth if rate is the criterion.

Rubidium and caesium entry, and cation interaction in frog skeletal muscle

Rb and Cs uptake by frog sartorius muscle was measured and the interaction between K, Rb, and Cs studied. Uptake of Rb from various mixtures of Rb and Na salts and the uptake of Cs from various mixtures of Cs and Na salts fell along single curves for a given temperature when plotted against a function of concentration x time of exposure. The relative exchangeabilities of K for K, Rb, and Cs, respectively, were 1:0.2:0.04. Uptakes of Rb or Cs from mixtures with K or with each other are shown to be consistent with predictions. Entry of Rb into previously K-depleted muscles, so that Na is displaced by Rb, was faster than the interchange of Rb with the muscle K. Uptake of labeled K from mixtures with Rb or Cs followed a course consistent with the hypothesis that when Rb or Cs has entered the ion-exchange region the K exchange is slowed down. In the case of Rb + K mixtures, the K exchange ultimately fell to the same rate as holds for Rb-K interchange, but Cs took longer to exert its full inhibitory effect. Experiments in which the internal-external resistance of fibers from a pair of muscles were measured,more » in solutions containing respectively 3 mm K or Rb with Na methyl sulfate, showed that the values in the Rb solution were 2 to 4 times those in the K solution. Experiments also indicated that the Cl exchange process follows the same pattern as that described for the cations. (TCO)« less

The IsomerRb84m

With the help of scintillation counters information on the isomer ${\mathrm{Rb}}^{84m}$ has been obtained. The isomer was produced by an ($n, 2n$) bombardment of ordinary Rb salts. The half-life has been determined as 21 min. Three gamma-rays have been observed at 0.239, 0.463, and 0.890 Mev. The last gamma-ray occurs in the product ${\mathrm{Kr}}^{84}$. Coincidence measurements show coincidences between the gamma-ray at 0.239 Mev and another of nearly the same energy, while coincidences between the 0.463 and the gamma-rays at 0.239 Mev are essentially negligible. A possible level scheme is discussed.