Mixtures Of Rubidium Research Articles

An ultracold, optically trapped mixture of 87Rb and metastable 4He atoms

We report on the realization of an ultracold (<25 μK) mixture of rubidium (87Rb) and metastable triplet helium (4He) in an optical dipole trap. Our scheme involves laser cooling in a dual-species magneto-optical trap, simultaneous MW- and RF-induced forced evaporative cooling in a quadrupole magnetic trap, and transfer to a single-beam optical dipole trap. We observe long trapping lifetimes for the doubly spin-stretched spin-state mixture and measure much shorter lifetimes for other spin-state combinations. We discuss prospects for realizing quantum degenerate mixtures of alkali-metal and metastable helium atoms.Graphical abstract

Recovery of rubidium and potassium alums from lithium-bearing minerals

Rubidium was recovered from lithium-containing solution from processing zinnwaldite, (KAl(Fe,Li)(Si3Al)O10F2), concentrate after Li2CO3 crystallization as a mixture of rubidium and potassium alums (RbAl(SO4)2.12H2O and KAl(SO4)2.12H2O). The course of individual reactions aiming at rubidium alum separation from carbonated solutions containing potassium as a main contaminant was studied on synthetic solutions. Before the alum precipitation, the original carbonated solution was converted to sulphate solution. Rubidium recovery efficiency at least 95% was achieved if the amount of the precipitation agent (Al2(SO4)3) ranged between 3.5 and 4.0 multiples of stoichiometric amount related to rubidium concentration in the processed solution. Under such conditions, precipitates obtained contain between 4.10 and 3.62% Rb and from 6.02 to 6.25% K and consist of on average 24% rubidium alum and 75% potassium alum.

Trimeric, cyclic Ti10-containing 27-tungsto-3-germanate [(α-Ti3GeW9O37OH)3(TiO3(OH2)3)]17−

Abstract The trimeric, cyclic polyanion [(α-Ti3GeW9O37OH)3(TiO3(OH2)3)]17− (Ti10) was synthesized by reaction of [A-α-GeW9O34]10− with K8[Ti4O4(C2O4)8] in a mixture of rubidium and lithium acetate buffers at 60 °C, and then crystallized as a mixed rubidium-potassium-sodium salt, Rb13K2Na2[(α-Ti3GeW9O37OH)3(TiO3(OH2)3)]·40H2O (Rb-Ti10). The title compound was characterized in the solid state by IR, single-crystal XRD, TGA and elemental analysis, and in solution by 183W-NMR. In order to prepare a pure sample of Rb-Ti10, several reaction parameters need to be carefully controlled, such as the ratio of rubidium and lithium acetate buffers, the choice of titanium precursor (K8[Ti4O4(C2O4)8]), the reaction temperature, and very importantly, the concentration of rubidium ions.

Spin-exchange optical pumping ofHe3with Rb-K mixtures and pure K

We have studied the efficiency of spin-exchange optical pumping SEOP in cells that contain either pure rubidium, mixtures of rubidium and potassium, or pure potassium. Optical pumping was performed with spectrally narrowed diode array lasers operating at either the wavelength of the Rb 5s1/2-5p1/2 transition 795 nm or the K 4s1/2-4p1/2 transition 770 nm. Calculations of the expected efficiency are shown for practical conditions and compared to measurements. We have measured the vapor density ratio in Rb-K mixture cells using absorption of white light. Our focus is on the conditions that are relevant for neutron spin filters, but the results are relevant to all applications of SEOP. We find that both Rb-K and pure K cells yield improvements in the spin-exchange efficiency, and each approach has its own advantages. Overall, the best results for high polarizing rate with high polarization were obtained with mixture cells with K-Rb vapor density ratios between 2 and 6.

Trirubidium cobalt tetrachloride nitrate(V), Rb3CoCl4NO3

The title compound, Rb3CoCl4NO3, is isostructural with K3ZnCl4NO3. It is built up from Rb+ cations, NO3− anions and [CoCl4]2− complex ions which form a layer-like arrangement: one layer contains only rubidium cations while the other contains a mixture of rubidium, nitrate and tetra­chloro­cobaltate ions. Both rubidium cations are ninefold coord­inated by three O atoms and six Cl ions. One Rb atom, the Co atom, two Cl atoms, the N atom and one O atom lie on a crystallographic mirror plane.

Radiation transport within the natural isotopic mixture of rubidium vapor after isotope selective excitation

The radiation transport within the natural isotopic mixture of rubidium is studied by detecting the time dependent resonance fluorescence after isotope selective excitation of87Rb or85Rb to the 52P3/2 state by the pulsed light of a laser diode. At atomic densities of about 1012 cm−3 the mean number of photon scatterings is 10 or 25 after excitation of87Rb or85Rb, respectively. Monte Carlo simulations of multiple photon scattering are used to reproduce the time dependent fluorescence signals. Satisfactory agreement between experiments and calculations can be achieved only if a radiative transfer of excitation energy between the different isotopes is considered. The energy transfer can be explained by radiative coupling of the different isotopes due to two partially overlapping hfs components of the 780 nm resonance line. As a test of our theoretical approach fluorescence signals recorded after excitation of87Rb and85Rb under identical experimental conditions are fitted both by using the same set of two parameters.

Exchange and direct mechanisms in heteronuclear alkali Penning ionisation

The authors measure rate coefficients for Penning ionisation occurring in a vapour mixture of rubidium and potassium at thermal energy. The experimental technique uses the mass spectrometry analysis of collisional currents resulting from continuous laser excitation of the atoms. They report the first experimental evidence concerning the non-occurrence of an exchange-type mechanism. Although a second exchange-type reaction cannot be discarded by their experimental results, it seems that Penning ionisation, involving low-lying excited alkali atoms, most probably proceeds via the direct mechanism.

Laser-induced fluorescence of the RbCs molecule

Laser-induced fluorescence of the RbCs molecule has been observed when a mixture of rubidium and cesium was irradiated by the 5682 Å line of Kr+ laser. A series of fluorescence lines of transitions to the vibrational levels up to v″=122 is observed and a continuous spectrum with banded diffraction structure is contiguous to it. The spectroscopic constants of the X 1Σ+ ground state are determined from the analysis of the fluorescence, and the potential curve is constructed by the RKR procedure. The dissociation energy De is determined to be 3833±5 cm−1 from the Birge–Sponer extrapolation. The potential curve of the excited state is estimated from the analysis of the fluorescence intensity.

Inelastic Collisions between Excited Alkali Atoms and Molecules. VIII. 62P1/2–62P3/2 Mixing and Quenching in Mixtures of Rubidium with H2, HD, D2, N2, CH4, and CD4

Excitation transfer between the 62P fine-structure substates in rubidium, induced in inelastic collisions with ground-state molecules, has been studied using techniques of sensitized fluorescence. Rubidium vapor in mixtures with various molecular gases was irradiated with each component of the 2P rubidium doublet in turn, and measurements of sensitized-to-resonance fluorescent intensity ratios yielded the following mixing cross sections Q12(2P1/2 → 2P3/2) and Q21(2P1/2 ← 2P3/2), as well as effective quenching cross sections Q1X(2P1/2 → 2XJ″) and Q2X(2P3/2 → 2XJ″). For collisions with H2: Q12(2P1/2 → 2P3/2) = (41 ± 5) Å2; Q21(2P1/2 ← 2P3/2) = (26 ± 3) Å2; Q1X(2P1/2 → 2XJ″) = (36 ± 9) Å2; Q2X(2P3/2 → 2XJ″) = (31 ± 8) Å2. For HD: Q12 = (42 ± 5) Å2; Q21 = (27 ± 4) Å2; Q1X = (47 ± 13) Å2; Q2X = (38 ± 10) Å2. For D2: Q12 = (42 ± 5) Å2; Q21 = (27 ± 4) Å2; Q1X = (28 ± 8) Å2; Q2X = (21 ± 7) Å2. For N2: Q12 = (107 ± 15) Å2; Q21 = (70 ± 10) Å2; Q1X = (128 ± 44) Å2; Q2X = (126 ± 33) Å2. For CH4: Q12 = (38 ± 6) Å2; Q21 = (24 ± 3) Å2; Q1X = (129 ± 41) Å2; Q2X = (114 ± 37) Å2. For CD4: Q12 = (52 ± 7) Å2; Q21 = (34 ± 5) Å2; Q1X = (82 ± 30) Å2; Q2X = (76 ± 22) Å2. An analysis of these results suggests the possibility of resonances with various molecular rotational and vibrational transitions.