Metallic Rubidium Research Articles

Clean, robust alkali sources by intercalation within highly oriented pyrolytic graphite.

We report the fabrication, characterization, and use of rubidium vapor dispensers based on highly oriented pyrolytic graphite (HOPG) intercalated with metallic rubidium. Compared to commercial chromate salt dispensers, these intercalated HOPG (IHOPG) dispensers hold an order of magnitude more rubidium in a similar volume, require less than one-fourth the heating power, and emit less than one-half as many impurities. Appropriate processing permits exposure of the IHOPG to atmosphere for over ninety minutes without any adverse effects. Intercalation of cesium, potassium, and lithium into HOPG has also been demonstrated in the literature, which suggests that IHOPG dispensers may also be made for those metals.

Rubidium hydrazinidoborane: Synthesis, characterization and hydrogen release properties

In this work we present rubidium hydrazinidoborane RbN2H3BH3 (RbHB), the newest and last member of the alkali metal derivatives of hydrazine borane N2H4BH3 (HB). It is shown that HB readily reacts with metallic rubidium in THF at room temperature to form RbHB under argon atmosphere. The molecular and crystal structures of this new compound are discussed on the basis of FTIR spectroscopy, 11B MAS NMR spectroscopy, and powder X-ray diffraction analyses. RbHB crystallizes in a monoclinic P21 (No. 4) unit cell where each Rb+ cation adopts octahedral coordination surrounded by six [N2H3BH3]− anions, which are two more than for e.g. LiN2H3BH3 (with tetrahedral coordination) in accordance with the larger size of Rb+. RbHB is isostructural to potassium hydrazinidoborane KN2H3BH3. Its dehydrogenation properties, evaluated by using thermogravimetric analysis, differential scanning calorimetry, and isothermal analysis, are compared to those of the parent HB as well as to analogous compounds in order to evaluate the potential of RbHB as hydrogen storage material. According to the presented data, the dehydrogenation properties of RbHB are much better than those of HB and are comparable to those of the lithium derivative. Our main results are reported therein.

Continuous-Wave Alkali Vapor Laser Pumped by a Ti-sapphire Laser with Narrow Linewidth

We have experimentally demonstrated the continuous wave rubidium and cesium lasers pumped by a Ti-sapphire laser with the linewidth of about 5 MHz. The pump and laser beams were orthogonally polarized and they can be separated by a polarized beam splitter (PBS). Two 4-cm-long cells were respectively filled with metallic rubidium and cesium as well as 300 Torr ethane as a buffer gas. A series of output couplers at different cell temperatures have been used and the optimal parameters have been found for earning the highest output. As a result, we have achieved a maximum output power of 111 mW with the optical to optical efficiency of 18.4% for a rubidium laser and a maximum output power of 136 mW with the optical to optical efficiency of 30% for a cesium laser, respectively. By considering there are no anti-reflection coatings on the surfaces of two cell end-windows, the output should be improved if the transmission attenuation is effectively decreased in the future.

Organometallic rubidium and cesium compounds of the 5,6;11,12-di-o-phenylene-tetracene dianion.

Twofold reduction of the title molecule 5,6;11,12-di-o-phenylenetetracene (DOPT) with an excess of metallic rubidium and cesium in the presence of strongly coordinating ethers like 18-crown-6-ether (18C6) and tetraglyme results in the formation of the first Rb(i) triple-decker complex and the first Cs(i) coordination polymer of the so far only sparsely studied polyaromatic planar hydrocarbon DOPT. Both compounds are extremely sensitive towards air and water in solution as well as in the solid state. Both compounds exhibit isomerism within their crystal lattices.

Rubidium 'whiskers' in a vapour cell

Crystals of metallic rubidium are observed ``growing'' from paraffin coating of buffer-gas-free glass vapor cells. The crystals have uniform square cross-section, $\approx 30 \mu$m on the side, and reach several mm in length.

Target irradiation facility and targetry development at 160 MeV proton beam of Moscow linac

A facility has been built and successfully operated with the 160 MeV proton beam of Moscow Meson factory LINAC, Institute for Nuclear Research (INR) of Russian Academy of Science, Troitsk. The facility was created for various isotope production goals as well as for fundamental nuclear investigations at high intensity beam (100 μA and more). An important part of the facility targetry system is a high-intensity beam monitoring collimator device. Measurements of the temperature distribution between collimator sectors, cooling water flow and temperature, and the beam current, provide an opportunity to compute beam losses and beam position. The target holder design allows easy insertion by manipulator and simultaneous bombardment of several different targets of various types and forms, and variation of proton energy on each target over a wide range below 160 MeV. The main target utilized for commercial 82Sr isotope production is metallic rubidium in a stainless-steel container. A regular wet chemistry method has been used in this process to recover radio-strontium. A new targetry technique based on adsorption of radio-strontium from liquid metallic rubidium has been explored and is under development. It was found that strontium may be extracted from molten rubidium on several metallic or oxide flat surfaces, with the temperature of the sorbing material about 130–170°C, and the temperature of the vessel with metallic rubidium about 240–270°C. This makes it possible to provide “on-line” 82Sr production and extraction on a very high intensity beam with the use of circulating liquid rubidium targets. The same idea has been found to be fruitful to extract “on-line” and selectively a number of radionuclides directly from liquid lead targets by chemosorption processes.

82Sr production from metallic Rb targets and development of an 82Rb generator system

A complete procedure for producing 82Sr/Rb generators is described. 82Sr was produced by bombarding metallic rubidium targets with 60 MeV protons with beam currents as high as 80 μA. The experimentally determined cross section for a thick target (61–48 MeV) agrees with the literature value of 100 mb. Production rates of about 0.2 mCi/μA-h with a 1.8 g/cm 2 target were achieved. The 82Sr was separated from the target by dissolving the rubidium metal in n-butanol then separating the strontium isotopes on a Chelex-100 column. A SnO 2 generator system was built from readily available components. Factors affecting generator design, performance and limitations included SnO 2 particle size, column length and eluant flow-rate.

Observation of Phasons in Metallic Rubidium

The heat-capacity anomaly caused by phasons---the collective excitations of an incommensurate charge-density wave---is identified in rubidium metal at 0.8 $^{\mathrm{o}}\mathrm{K}$. Data analysis leads to a value ${\ensuremath{\Theta}}_{\ensuremath{\phi}}=4.5\ifmmode^\circ\else\textdegree\fi{}$K for the phason cutoff frequency. The velocity ratio of a purely longitudinal to a purely transverse phason is found to be \ensuremath{\sim}11.

Resonance magnetique nucleaire dans le rubidium et le cesium metalliques

The Ruderman-Kittel interaction has been deduced from the line widths at 1.4°K in metallic rubidium and caesium. The spin-lattice relaxation time and the atomic self-diffusion process contribute to the line width at room temperature. The study of the signal in the dispersion mode with a strong r.f. magnetic field applied, provides a precise determination of the indirect exchange coupling constant. By studying the absorption signal with a low radiofrequency level we have found evidence for the existence of pseudo-dipolar indirect interaction and we have estimated the order of magnitude of that interaction.

Nuclear Spin Relaxation in Alkali Metals

Nuclear magnetic resonance measurements have been made in metallic lithium, sodium, and rubidium, using pulsed radio-frequency power. The experimental data are values of ${T}_{1}$, the spin-lattice relaxation time, and of ${T}_{2}$, the inverse line width or spin-spin relaxation time. Measurements were made at several Larmor frequencies and at temperatures between -65\ifmmode^\circ\else\textdegree\fi{}C and 250\ifmmode^\circ\else\textdegree\fi{}C. Over a considerable temperature range, ${T}_{1}$ is found to be primarily determined by interaction with the conduction electrons. The magnitudes of ${T}_{1}$ agree fairly well with the Korringa theory in all three metals. The lithium data in particular indicate that $\frac{{P}_{f}}{{P}_{a}}\ensuremath{\cong}0.6$. In lithium and sodium a dependence of ${T}_{1}$ on the resonance frequency is observed, which cannot be explained on the basis of the Korringa theory. Information about the atomic self-diffusion process is also obtained. Portions of the ${T}_{1}$ and ${T}_{2}$ data are interpreted using the theory of Bloembergen, Purcell, and Pound. In addition, some of the ${T}_{1}$ data are interpreted in terms of the lattice diffusion theory of Torrey. These analyses yield values for $D$, the coefficient of self-diffusion, of ${{0.24}_{\ensuremath{-}0.10}}^{+0.17}\ifmmode\times\else\texttimes\fi{}\mathrm{exp}(\ensuremath{-}13200\ifmmode\pm\else\textpm\fi{}\frac{400}{\mathrm{RT}})$ ${\mathrm{cm}}^{2}$/sec in lithium and ${{0.20}_{\ensuremath{-}0.15}}^{+0.56}\ifmmode\times\else\texttimes\fi{}\mathrm{exp}(\ensuremath{-}10000\ifmmode\pm\else\textpm\fi{}\frac{600}{\mathrm{RT}})$ ${\mathrm{cm}}^{2}$/sec in sodium. Although there is some ambiguity in the interpretation of the rubidium data, they indicate $D\ensuremath{\cong}0.23\mathrm{exp}(\ensuremath{-}\frac{9400}{\mathrm{RT}})$ ${\mathrm{cm}}^{2}$/sec. Unusual broadenings of the resonance lines are observed at the melting points in all three metals. These broadenings are not presently understood, but some features of the data can be correlated with a mechanism involving magnetic local fields which arise from lattice imperfections.

Dispersion in vapours of the alkali metals

In the ‘Proceedings’ of the Royal Society, A, vol. 84, p. 209, I gave an account of experiments with Potassium vapour, which had for their object the determination of the dispersion curve for the vapour. The effect of the first three pairs of lines of the principal series was quantitatively estimated, and it appeared that certain conclusions could be drawn as to the numbers of systems taking part in the absorption of light. The present communication deals with further experiments of the same kind with vapours of Sodium and Rubidium, and again with the vapour of potassium, as far as regards a temperature effect, which will be discussed later. The experiments were made possible by a grant from the Royal Society, which enabled me to obtain metallic rubidium, and I am glad to take this opportunity of thanking the Government Grant Committee. In a former paper I gave results of the measurements of wave-length of the principal series lines for rubidium obtained in the absorption spectrum. This spectrum was obtained by heating rubidium chloride with metallic potassium; enough vapour was formed to give an absorption spectrum showing 25 lines of the series. With metallic rubidium it is easier to get the absorption spectrum, and the list of lines has been extended to include 30 members. A better reading microscope has been available since the original measurements, so that the complete series of lines has been remeasured. The method adopted was the same as that described in the paper referred to, so that there is no need for further description.