Thallium Fluoride Research Articles

Thallium-Fluorides Revisited: Crystal Chemistry of TlHF2, Tl2[MF6]·2TlF, and Tl2[MF6]·TlCl (M = Si and Ge).

Although the formation of thallium hydrogen fluorides TlHxFx+1 (x = 1, 1.5, 2, 3, 5, 6.5, and 7) from TlF and HF was reported in the 1970s, little is known about the corresponding crystal structures. To shed light on the crystal chemistry of the thallium fluorides, we reinvestigated the structure of α-TlHF2, which was obtained by crystallization of TlF from 50% HF at room temperature. We disclose that β-TlHF2 is isostructural with α-MHF2 (M = K, Rb, and Cs), γ-TlHF2 is isostructural with β-MHF2 (M = K and Rb), whereas α-TlHF2 crystallizes in an unusual structure type. During the reaction of TlHF2 with the glass of the microscope slide, crystals of the previously unknown compound Tl2[SiF6]·2TlF were formed. We disclose that the related Tl2[GeF6]·2TlF can be obtained by the crystallization of stoichiometric amounts of Tl2[GeF6] with TlF from water at room temperature. The crystal structures of α-TlHF2, Tl2[SiF6]·2TlF, Tl2[SiF6]·TlCl, Tl2[GeF6]·2TlF, Tl2[GeF6]·TlCl, and Tl2[GeF6] were determined by single-crystal X-ray diffraction analysis. The crystal structures of α-TlF and Tl2[SiF6]·xTlF (x = 0, 1) were redetermined at low temperatures.

Reassessing the potential of TlCl for laser cooling experiments via four-component correlated electronic structure calculations.

Following the interest in the experimental realization of laser cooling for thallium fluoride (TlF), determining the potential of thallium chloride (TlCl) as a candidate for laser cooling experiments has recently received attention from a theoretical perspective [Yuan et al., J. Chem. Phys. 149, 094306 (2018)]. From these ab initio electronic structure calculations, it appeared that the cooling process, which would proceed from transitions between a3Π0 + and X1Σ0 + states, had as a potential bottleneck the long lifetime (6.04 µs) of the excited state a3Π0 +, that would make it very difficult to experimentally control the slowing zone. In this work, we revisit the electronic structure of TlCl by employing four-component Multireference Configuration Interaction (MRCI) and Polarization Propagator (PP) calculations and investigate the effect of such approaches on the computed transition dipole moments between a3Π0 + and a3Π1 excited states of TlCl and TlF (the latter serving as a benchmark between theory and experiment). Whenever possible, MRCI and PP results have been cross-validated by four-component equation of motion coupled-cluster calculations. We find from these different correlated approaches that a coherent picture emerges in which the results of TlF are extremely close to the experimental values, whereas for TlCl the four-component calculations now predict a significantly shorter lifetime (between 109 and 175ns) for the a3Π0 + than prior estimates. As a consequence, TlCl would exhibit rather different, more favorable cooling dynamics. By numerically calculating the rate equation, we provide evidence that TlCl may have similar cooling capabilities to TlF. Our analysis also indicates the potential advantages of boosting stimulated radiation in optical cycles to improve cooling efficiency.

CeNTREX: a new search for time-reversal symmetry violation in the 205Tl nucleus

The Cold molecule Nuclear Time-Reversal EXperiment (CeNTREX) is a new effort aiming for a significant increase in sensitivity over the best present upper bounds on the strength of hadronic time reversal (T) violating fundamental interactions. The experimental signature will be shifts in nuclear magnetic resonance frequencies of 205Tl in electrically-polarized thallium fluoride (TlF) molecules. Here we describe the motivation for studying these T-violating interactions and for using TlF to do so. To achieve higher sensitivity than earlier searches for T-violation in TlF, CeNTREX uses a cryogenic molecular beam source, optical state preparation and detection, and modern methods of coherent quantum state manipulation. Details of the measurement scheme and the current state of the apparatus are presented, with quantitative measurements of the TlF beam. Finally, the estimated sensitivity and methods to control systematic errors are discussed.

Correction to: Comparative study of structural and superconducting properties of (Cu0.5Tl0.5)Ba2Ca2Cu3O10-δ phase substituted by copper fluoride and thallium fluoride

Correction to: Comparative study of structural and superconducting properties of (Cu0.5Tl0.5)Ba2Ca2Cu3O10-δ phase substituted by copper fluoride and thallium fluoride

Comparative study of structural and superconducting properties of (Cu0.5Tl0.5)Ba2Ca2Cu3O10-δ phase substituted by copper fluoride and thallium fluoride

Comparative study of structural and superconducting properties of (Cu0.5Tl0.5)Ba2Ca2Cu3O10-δ phase substituted by copper fluoride and thallium fluoride

Effects of thallium fluoride and yttrium on structure, electrical properties and ac losses susceptibility of (Bi,Pb)-2234 superconductors

We have studied the effects of thallium fluoride TlF3 and yttrium Y3+ on phase formation and superconducting transport properties of Bi1.8−xTlxPb0.35Sr2Ca3−zYzCu4O12+δF3x superconductors. The samples are characterized by X-ray diffraction, SEM photographs, resistivity and AC susceptibility χ′(χ″) measurements. The study showed that the melting point of the sample doped with thallium fluorine and yttrium as well as the formation temperature is decreased. We have found that the agreement factors of structure (Rp,Rwp,GOF) and the superconducting parameters as the transition width, the activation energy, the residual and normal resistivity were enhanced with TlF3 and Y3+ doping. This behavior attests of the improvement of flux pinning strength into the grains and their coupling matrix. The inter-granular AC loss peak temperature was observed to increase as doping which is mainly due to a strong links between the grains. However, it is widely decreased with magnetic field. The maximum of susceptibility (χmax'') and partial susceptibility of matrix (χm,max''), and the effective volume fraction of the grains (fg) are determined on the basis of the critical state model which proved a great improvement with doping under applied field of 2 and 10 Oe. The estimated values of matrix susceptibility through this model revealed the well decrease of the inter-granular losses with doping as well.

Measurement of the molecular dipole moment and the hyperfine and Λ -doublet splittings of the BΠ13 state of thallium fluoride

We report high-precision measurements on the thallium fluoride $\tilde{J} = 1$ hyperfine manifold of the $B^3\Pi_1$ ($\nu = 0$) state. This state is of special interest because it is central to an optical cycling scheme that is envisioned to play an important role in enhancing the sensitivity of the CeNTREX nuclear Schiff-moment experiment presently under construction. The measurements are made by monitoring the fluorescence induced by narrow-band laser excitation of a cryogenic molecular beam. We use a multipass arrangement of the laser beam to enhance fluorescence. When viewed with a camera, we can spatially resolve images from adjacent passes that approach the molecules from opposing directions. These images yield a sensitive visual method to identify the central frequency of a transition. Coupling these line-center determinations with frequency calibration from an acousto-optic modulator has allowed a more precise determination of the $\tilde{J} = 1$ manifold of hyperfine level splittings. We observe Stark shifts of the $\tilde{J} = 1$ levels and infer a permanent electric dipole moment of 2.28(7) D and $\Lambda$-doublet splittings for the $F_1' = 1/2$ and $F_1' = 3/2$ manifolds of 14.4(9) MHz and 17.4(11) MHz, respectively.

Λ doubling in the B3Π1 state of TlF

Thallium monofluoride (TlF) is a prime candidate molecule for precision measurements aimed at discovering new physics. Optical cycling on the B $\leftarrow$ X transition around 271 nm enhances this potential. Hyperfine resolved ultraviolet spectra have been reported to determine the degree of rotational level mixing in the B-state and the efficiency of laser cooling on the B $\leftarrow$ X transition [E. B. Norrgard ${\it et~al.}$, Physical Review A ${\bf 95}$, 062506 (2017)]. Using these high-resolution spectra, the hyperfine structure in the B-state of TlF is re-analysed and the magnitude of the $\Lambda$-doubling in the B-state is discussed.

Electronic structure and spectroscopy of the low-lying electronic states of thallium fluoride: MRCI + Q study including spin-orbit coupling

The low-lying electronic states of thallium fluoride (TlF) are investigated using the multi-reference configuration interaction method including the core-valence and the spin-orbit coupling effects. Based on the calculated potential energy curves, the spectroscopic constants of the bound states of TlF are determined, which are in accordance with available theoretical and experimental results in the literature. The transition dipole moments, Franck-Condon factors, and the radiative lifetimes of the a3Π0+- X1Σ+0+and a3Π1- X1Σ+0+ transitions have been reported. Our study is expected to be helpful for understanding the spectroscopy and dynamics of electronic excited states of the TlF molecule.

The effect of TlF3 substitution on the weak links behaviour and AC susceptibility of Bi1.8−xTlxPb0.35Sr2Ca2Cu3OyF3x superconductors

We have studied the thallium fluoride (TlF3) doping and AC field dependence of the weak links behaviour and AC susceptibility of Bi1.8−xTlxPb0.35Sr2Ca2Cu3OyF3x superconductors with range of x = 0, 0.05, 0.10 and 0.15. The estimated value of the peak temperature (Tp) from the derivative of the resistivity curve (dρ/dT) is increased with TlF3 doping at 0 and 0.5 teslaand attest on both intragranular and weak links transition, while the full width at half maximum (FWHM) value is decreased. The susceptibility measurements χ′(χ″) show that as the magnetic field increases the intra and intergranular AC loss peaks shift to lower temperature with broadening. It was found that the onset temperature of diamagnetism Tc is increased with TlF3 doping. However, the intergranular peak temperature Tpj decreased with increasing magnetic field and TlF3 amount. This behaviour was explained by the poor connectivity between the grains caused by the presence of weak links or secondary phases. The calculated volume fraction of the grains (fg) was found to improve with increasing TlF3 doping and AC magnetic field. Furthermore, the estimated values of the maximum of the extracted matrix susceptibility (χm,max″) by using a critical state model proved that the intergranular losses are minimized with TlF3 doping. On the other hand, the obtained results shown that the coupling between the grains is rather weak than the coupling within the grains and attested of the improvement of superconducting parameters in the doped samples.

Improvement of superconducting properties of (Bi, Pb)-2223phase by TlF3 doping

In this work, the superconducting properties of thallium fluoride (TlF3)doped Bi1.8−xTlxPb0.35Sr2Ca2Cu3OyF3x(x=0–0.15)compounds are presented. The X-ray diffraction analysis shows that the proportion of (Bi, Pb)-2223phase is higher than the secondary (Bi, Pb)-2212one in all samples and its highest value is about 82.74%for x=0.05. From the resistivity curves, the highest values of the onset critical transition temperature (Tc.on), the offset critical transition temperature (Tc.off) are seen for x=0.10. The calculation of activation energy (U0) in the TAFF (thermally activation flux flow) region proves the positive effect of TlF3 doping on the dissipative behavior of energy near Tc.off. Flux pinning strength is enhanced by increasing TlF3content up to x=0.10, and decreased by the application of a magnetic field. The other superconducting parameters like T(Hc2), T(Hirr), ξ(0) and μ0Hc2(0) are also improved significantly by doping. The obtained results of Ac susceptibility measurements show that the onset temperature of diamagnetism is improved by TlF3 doping, in accordance with the resistivity results.

Functionalization of Borate Networks by the Incorporation of Fluoride: Syntheses, Crystal Structures, and Nonlinear Optical Properties of Novel Actinide Fluoroborates

The boric acid flux reactions of uranyl nitrate with sodium, potassium, rubidium, or thallium fluoride result in the formation of a novel family of uranyl(VI) fluoroborate materials. These compounds are Na[(UO2)B5O8(OH)F]·H2O (NaUBOF-1), K[(UO2)B5O8(OH)F] (KUBOF-1), K11[(UO2)6B24O36F22)](H2BO3) (KUBOF-2), Rb[(UO2)B5O8(OH)F] (RbUBOF-1), and Tl[(UO2)B5O8(OH)F] (TlUBOF-1). A new neptunium(VI) fluoroborate that is isotypic with NaUBOF-1, Na[(NpO2)B5O8(OH)F]·H2O (NaNpBOF-1), was synthesized via the boric acid flux reaction of neptunium(VI) nitrate with sodium fluoride. These new actinide fluoroborates share a common structural motif consisting of a linear actinyl (U(Np)O22+) cation surrounded by BO3 triangles and BO4 tetrahedra to create an U(Np)O8 hexagonal bipyramidal environment around uranium or neptunium. The borate anions bridge between actinyl units to create layers. B–F bonds were formed during the reactions to yield BO3F tetrahedral units. The BO3F tetrahedra and additional BO3 triangles extend from the actinyl polyborate layers and are directed approximately perpendicular to the layers. A novel actinyl borate layered topology was found in K11[(UO2)6B24O36F22)](H2BO3) (KUBOF-2). Except for K[(UO2)B5O8(OH)F] (KUBOF-1) and K11[(UO2)6B24O36F22)](H2BO3) (KUBOF-2), all of the other actinide fluoroborate phases adopt noncentrosymmetric space groups. Tl[(UO2)B5O8(OH)F] (TlUBOF-1), which can be obtained as a pure phase, displays second-harmonic generation of 532-nm light from 1064-nm light.

Stability of Gaseous Thallium Monofluoride as TlF0, TlF+, and TlF2+.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Stability of Gaseous Thallium Monofluoride as TlF0, TlF+, and TlF2+

Stability of Gaseous Thallium Monofluoride as TlF⁰, TlF⁺, and TlF²⁺

Bridging fluorides and hard/soft mismatch in d6 and d8 complexes: the case of [Tl(mu-F)3Ru(PPh3)3

[RuCl2(PPh3)3] reacts with thallium(I) fluoride to give either [Tl(mu-F)3Ru(PPh3)3] (1) or [Tl(mu3-F)(mu2-Cl)2Ru2(mu2-Cl)(mu2-F)(PPh3)4] (2) depending on the excess of TlF used. Both 1 and 2 were fully characterized, including X-ray structure determinations. Complex 1 reacts with dihydrogen to form the known ruthenium hydride complex [Ru(H)2(H2)(PPh3)3] upon hydrogenolysis of the Ru-F bond. The reaction of 1 with activated alkyl bromides (R-Br) gives the corresponding alkyl fluorides and the trinuclear complex [Tl(mu3-F)(mu2-F)(mu2-X)Ru2(mu2-Br)(mu2-F)(PPh3)4] (X=Br, F) (3), whose structure closely resembles that of 2. However, 1 is not active as catalyst for the nucleophilic fluorination of R-Br in the presence of thallium fluoride. The effect of the bridging coordination mode of fluoride on the Ru-F bond is discussed in terms of the HSAB principle, which suggests a more general model for predicting the stability of d6 and d8 complexes containing hard ligands (such as fluoro, oxo, and amido).

The Crystal Structures of Thallium(I) Fluoride

The effects of temperature and pressure on the crystal structures of thallium(I) fluoride have been investigated using powder neutron diffraction, with the aim of resolving the uncertainties present in the literature. Under ambient conditions, TlF adopts an orthorhombic structure in space group Pbcm with Z=4 and cell parameters a=6.09556(8) Å, b=5.48860(7) Å, and c=5.18300(7) Å. This structure can be derived from an idealized rocksalt-type arrangement, though with extensive distortions of the anion sublattice due to the presence of the 6s2 inert pair of the Tl+ Above 355 K TlF becomes tetragonal with Z=2, a=3.78283(2) Å, c=6.12312(5) Å, and space group P4/nmm. The behavior of the compound is also studied under hydrostatic pressure but, contrary to previous reports, no structural transition was observed and TlF remains orthorhombic up to at least 3.5 GPa. The compressibility is greatest along the a and b axes. The relationship between the ambient- and high-temperature structures of TlF is described and the influence of the inert pair discussed in relation to the massicot structured polymorph of PbO.

A comparison of finite basis set and finite difference Hartree-Fock calculations for the InF and TlF molecules

A comparison is made of the finite basis set approach (the algebraic approximation) and finite difference methods in calculations using the Hartree-Fock model for the ground (X1Σ+) states of the heaviest Group IIIb fluorides: indium fluoride and thallium fluoride molecules. The XF molecules, X = In, Tl, are considered as a prototype for systems containing increasingly heavy atoms and a number of electrons. New finite difference Hartree-Fock calculations for the GaF ground state improve upon earlier results. The convergence of the calculations carried out within the algebraic approximation is monitored by employing systematically constructed basis sets of increasing size. The dependence of the finite difference calculations on the numerical grid employed is discussed. For the InF molecule, the total Hartree-Fock energy obtained with a grid of 595 × 595 points lies 15μΕh below the finite basis set energy. For the ground h state of TlF the finite basis set energy lies about 61μΕh above the converged finite difference result obtained on a grid of 595 × 595 points. For the TlF molecule, the matrix element required to evaluate the electric dipole moment volume interaction for the elementary particles in the Tl nucleus is evaluated from the finite difference Hartree-Fock wavefunction.

Practicing the Poor Man's Brand of Particle Physics

This article describes various small-scale experiments that are being conducted to detect atomic dipoles. These experiments are designed expressly to test one prediction of supersymmetry - that of an electric dipole in atoms of less than 10[sup [minus]27] cm. The researchers can presently detect an offset of less than 10[sup [minus]26] cm between an atom's positive and negative charge. Three groups are measuring the precession of atoms exposed to electric fields. They are studying atoms of cesium and mercury, and molecules of thallium fluoride.

Search for time-reversal-symmetry violation in thallium fluoride using a jet source.

Search for time-reversal-symmetry violation in thallium fluoride using a jet source.

Solvatation et complexation des métaux dans les mélanges eau – fluorure d'hydrogène. Sn, Cd, Pb et Tl

The behavior of tin and thallium has been studied in water–HF mixtures. The formation of thallium fluoride complexes was not observed. Tin Sn2+ forms two complexes, SnF2 and SnF+, in mixtures containing less than 60% in HF. SnF2 is strong enough to prevent the formation of chloride complexes. SnF62− and SnF5− have been determined for Sn4+ in the same solutions. The relatively high strength of the tin fluoride complexes is reflected in the R0 (M) function. In fact, all the metals studied, Sn, Cd, Pb, and Tl, are less solvated in water–HF mixtures than in water, except for the case where the fluoride complex is strong, i.e., tin. HF2− seems to be the complexing species at high HF concentrations. Keywords: polarography, thallium, tin, cadmium, lead, hydrogen fluoride. [Journal translation]