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A novel source of polarized hydrogen and deuterium molecules has been tested. The use of sextupole superconducting magnets allows us to select molecules with the nuclear spin projection -1 for hydrogen and -2 for deuterium. The me...
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A novel source of polarized hydrogen and deuterium molecules has been tested. The use of sextupole superconducting magnets allows us to select molecules with the nuclear spin projection -1 for hydrogen and -2 for deuterium. The measured beam intensity of polarized hydrogen molecules for the nozzle temperature range of 6.5-30 K and a gas flow rate up to 5 · 10~(-2) Torr • 1/s is presented. The measured flux of polarized hydrogen molecules of ≈ 3 • 10~(12) mol/s is in reasonable agreement with estimations. The obtained results can be used as a basis for the development of a high-intensity source of polarized molecules.
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We calculate elastic and positronium (Ps) break-up cross sections for collisions of Ps with the polar molecules CO, HCl, and LiF in the fixed-nuclei approximation. We incorporate electron exchange and correlation for these process...
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We calculate elastic and positronium (Ps) break-up cross sections for collisions of Ps with the polar molecules CO, HCl, and LiF in the fixed-nuclei approximation. We incorporate electron exchange and correlation for these processes by using the free-electron-gas model developed earlier for Ps scattering by rare-gas atoms, N_2, O_2, and CO_2 molecules. The present target molecules provide a range of dipole moments from the weakly polar CO to the strongly polar LiF. We find that Ps scattering is similar to electron scattering when the cross sections are plotted as a function of projectile velocity for the targets with smaller dipole moments (CO, HCl). However, we do not see such a similarity for LiF which has a large dipole moment. Below the Ps break-up threshold we observe resonance structures similar to those obtained earlier for the other molecular targets that we have studied.
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Taking into account the deformation of the Fermi surface, we investigate the spin-singlet and -triplet BCS pairings in a mixture of fermionic polar molecules with two different hyperfine states. In particular, we explore the relat...
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Taking into account the deformation of the Fermi surface, we investigate the spin-singlet and -triplet BCS pairings in a mixture of fermionic polar molecules with two different hyperfine states. In particular, we explore the relation between the critical temperatures and the Fock-exchange interaction. We also show that, by tuning short-range interaction between interspecies molecules, the singlet- and triplet-paired superfluids may coexist.
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Laser cooling is a powerful method to control molecules for applications in precision measurement, as well as quantum information, many-body physics, and fundamental chemistry. However, many optically active metal centers in valen...
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Laser cooling is a powerful method to control molecules for applications in precision measurement, as well as quantum information, many-body physics, and fundamental chemistry. However, many optically active metal centers in valence states which are promising for these applications, especially precision measurement, are difficult to laser cool. In order to extend the control afforded by laser cooling to a wider array of promising atoms, we consider the use of small, hypermetallic molecules that contain multiple metal centers.We provide a detailed analysis of YbCCCa and YbCCAl as prototypical examples with different spin multiplicities and consider their feasibility for precision measurements making use of the heavy Yb atom.We find that these molecules are linear and feature metal-centered valence electrons and study the complex hybridization and spin structures that are relevant to photon cycling and laser cooling. Our findings suggest that this hypermetallic approach may be a versatile tool for experimental control of metal species that do not otherwise efficiently cycle photons and could present a relevant platform for state-of-the-art precision measurements.
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Spin polarization effects play an important role in the theory of isotropic hyperfine interactions foraromatic protons. The spin polarization gives rise to significant isotropic proton hyperfineinteractions—spin-dependent one-ele...
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Spin polarization effects play an important role in the theory of isotropic hyperfine interactions foraromatic protons. The spin polarization gives rise to significant isotropic proton hyperfineinteractions—spin-dependent one-electron properties—smaller than 0 MHz and the effect has beentheoretically described [H. M. McConnell and D. B. J. Chesnut, Chem. Phys. 28, 107 (1958)]. Theinfluence of spin polarization on the zero field splitting parameters, which are spin-dependenttwo-electron properties, has not been clearly identified yet. A phenomenological equation isproposed here for the contribution of spin polarization to the zero field splitting parameter D inanalogy to McConnell's equation for hyperfine interactions. The presence of the effect isdemonstrated in a series of calculations on polyacenes in the triplet state and turns out to beresponsible for up to 50% of the D parameter in the case of naphthalene! It is found thatspin-unrestricted single-determinant methods, including the widely used density functional theorymethods, do not accurately reproduce the two-electron reduced electron density required for theevaluation of two-electron spin-dependent properties. For the accurate calculation of zero fieldsplitting parameters by quantum chemical methods, it thus seems necessary to resort to correlatedab initio methods which do not give rise to spin contamination and which do provide an accuratedescription of the two-electron reduced electron density.
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We study the entanglement of two adsorbed polar molecules in static electric fields. The concurrence is estimated to quantify the entanglement. The adsorbed molecules reveal significant rotational characteristics, such as anticros...
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We study the entanglement of two adsorbed polar molecules in static electric fields. The concurrence is estimated to quantify the entanglement. The adsorbed molecules reveal significant rotational characteristics, such as anticrossing features, due to the influences of electric field and quantum confinement. Numerical results demonstrate that these rotational properties dominate the amount and profile of concurrence. At zero temperature, an enhanced concurrence is obtained near the anticrossing in the ground state. Moreover, we analyze the effect of temperature on the concurrence. The temperature-dependent concurrence displays a suppressed behavior, especially at the anticrossing.
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Long distance interactions of ammonia, hydrogen fluoride and water molecules adsorbed on a nickel (1 1 1) surface have been investigated using density functional theory (DFT) and a classical electrostatic model. The DFT approach u...
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Long distance interactions of ammonia, hydrogen fluoride and water molecules adsorbed on a nickel (1 1 1) surface have been investigated using density functional theory (DFT) and a classical electrostatic model. The DFT approach uses periodic boundary conditions, the generalized gradient approximation and plane wave basis functions. In the classical approach, the molecules are treated as point dipoles and the metal surfaces are modelled using the image-charge method. The classical and DFT interaction energies agree well, and the image-charge method can thus be used as a simple description of interactions between molecules and metal surfaces.
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Long distance interactions of ammonia, hydrogen fluoride and water molecules adsorbed on a nickel (1 1 1) surface have been investigated using density functional theory (DFT) and a classical electrostatic model. The DFT approach u...
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Long distance interactions of ammonia, hydrogen fluoride and water molecules adsorbed on a nickel (1 1 1) surface have been investigated using density functional theory (DFT) and a classical electrostatic model. The DFT approach uses periodic boundary conditions, the generalized gradient approximation and plane wave basis functions. In the classical approach, the molecules are treated as point dipoles and the metal surfaces are modelled using the image-charge method. The classical and DFT interaction energies agree well, and the image-charge method can thus be used as a simple description of interactions between molecules and metal surfaces.
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Enthalpies of solution of dibenzo24crown8 in tetrachlormethane, benzene, chloroform, pyri dine, acetone, acetonitrile, DMF, DMSO and propylene carbonate have been determined by calorimetric method at 298.15 K. The changes in entha...
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Enthalpies of solution of dibenzo24crown8 in tetrachlormethane, benzene, chloroform, pyri dine, acetone, acetonitrile, DMF, DMSO and propylene carbonate have been determined by calorimetric method at 298.15 K. The changes in enthalpy of solutesolvent interaction for the transfer the ether from inert tetrachlormethane into various solvents have been calculated from the obtained data. The thermochemical characteristics obtained for dibenzo24crown8 have been compared with similar ones for dibenzo18 crown6 having a smaller cycle size. It has been found that an exothermicity of solutesolvent interaction changes to a lesser extent for transfer of the larger cyclic ether into polar solvents. But the effect increases more sharply for the transfer to chloroform. It has been concluded that the contribution from electrostatic interaction with solvent decreases with an increase of the cycle size as result of the increasing structural flexibility and decreasing polarity of cycle. But the contribution from hydrogen bonding with chloroform becomes larger due to an increase in the number of donor atoms of the ether molecules. It was ascertained that the ability to bind specifically acetonitrile molecules disappears in going from 18merous to 24mer ous cycle.
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Electrorheological (ER) fluid is usually prepared by suspending the particles into dielectric oil. Recently developed polar molecule dominated ER (PM-ER) fluid is consisted of solid particles with polar molecules coating or adsorb...
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Electrorheological (ER) fluid is usually prepared by suspending the particles into dielectric oil. Recently developed polar molecule dominated ER (PM-ER) fluid is consisted of solid particles with polar molecules coating or adsorbing on their surfaces, which is denoted as PM(S)-ER fluid. We have reviewed the main characteristics of PM(S)-ER fluid and explained some observed phenomena. However the lifetime of PM(S)-ER fluid in practical applications is too short because of the friction loss of the polar molecules on the particles. In order to improve the lifetime of ER fluid a new type PM-ER fluid denoted as PM(L)-ER fluid has been developed by dissolving polar molecules into oil instead of adsorbing on the particles. The lifetime of PM(L)ER fluid is 5 times longer than that of PM(S)-ER fluid, while the shear stress keeps high enough. The manufacture procedure of PM (L)-ER fluid is simple, in addition, the performance and repeatability of the material are easily controlled.
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