The quark model and b baryons

The recent observation at the Tevatron of (uub and ddb) baryons within 2 MeV of the predicted Σ_b-Λ_b splitting and of baryons at the Tevatron within a few mega electron volts (MeV) of predictions has provided strong confirmation for a theoretical approach based on modeling the color hyperfine interaction. The prediction of  = 5790-5800 MeV is reviewed and similar methods used to predict the masses of the excited states and . The main source of uncertainty is the method used to estimate the mass difference m_b-m_c from known hadrons. We verify that corrections due to the details of the interquark potential and to Ξ_b- mixing are small. For S-wave qqb states we predict , and . For states with one unit of orbital angular momentum between the b quark and the two light quarks we predict , and . Results are compared with those of other recent approaches.     

Model calculations of the energy band structures of double stranded DNA in the presence of water and Na ions

Using the ab initio Hartree-Fock crystal orbital method in its linear combination of atomic orbitals form we have calculated the band structures of poly(-) and poly(-). Here, besides the nucleotide bases, the sugar and phosphate parts of the nucleotide were also taken into account together with their first water shell and Na⁺ ions. We use the notation with a tilde above the abbreviation of a base for the whole nucleotide; for instance poly() means a guanine base with the deoxyribose and PO₄⁻ groups to which it is bound. The obtained band structures were compared with previous single chain calculations as well as with the earlier poly(-) and poly(-) calculation without water but in the presence of counterions. One finds that all the bands of poly(-) and poly(-) are shifted considerably upwards as compared to the previous single chain results (poly(), poly(), poly() and poly()). This effect is explained by the ∼0.2e charge transfer from the sugars of both chains to the nucleotide bases. The fundamental gaps between the nucleotide base-type highest filled and lowest unfilled bands are decreased in both cases by 1-3 eV, because the valence bands are purine-type and the conduction bands pyrimidine-type, respectively, while in the case of single homopolynucleotides they belong to the same base. We also pointed out that the LUMO is mainly Na⁺-like in both investigated cases and several unoccupied bands (belonging to the Na⁺ ions, the phosphate group and the water molecules) can be found between this and the first unoccupied pyrimidine-like empty band.     

Repulsive and bound parts of the interatomic potentials of the lowest singlet electronic energy states of the MeRg complexes (Me = Zn, Cd; Rg = He, Ne, Ar, Kr, Xe)

Laser-induced fluorescence excitation spectra of MeRg (Me = Zn, Cd; Rg = He, Ne, Ar, Kr, Xe) complexes were recorded using the D¹ ← X¹ free ← bound transition. The complexes were produced in their ground state in a free-jet expansion beam and excited with a dye-laser beam directly to the excited state. Analysis of free ← bound unstructured profiles provided a shape of the repulsive part of the D¹-state potentials. Valence ab initio calculations of the ZnRg and CdRg ground- and excited-state potentials and electronic transition dipole moments for the studied transition were performed, taking scalar relativistic and spin-orbit effects into account. Results of the calculations show regularities and correlations in the repulsive branches and bound wells of the X¹- and D¹-state potentials as well as provide information on the bonding character in both electronic energy states. The trends were compared with available experimental results for ZnRg and CdRg as well as for MgRg and HgRg.     

The effect of the Bi source on optical properties of Bi2Te3 nanostructures

nanostructures were synthesized by using different Bi sources via a simple solvothermal process, in which and BiCl₃ were used as the Bi sources. Optical properties of nanostructures prepared with and BiCl₃ as the Bi sources were investigated by micro-Raman spectroscopy. The Raman scattering spectrum of hexagonal nanoplates prepared by using as the Bi source shows that the infrared (IR) active mode A_1u, which must be odd parity and is Raman forbidden for bulk crystal due to its inversion symmetry, is greatly activated and shows up clearly in the Raman scattering spectrum. We attribute the appearance of the infrared active A_1u mode in the Raman spectrum to crystal symmetry breaking of hexagonal nanoplates. However, the Raman scattering spectrum of nanostructures with irregular shape prepared by using as the Bi source only exhibits the two characteristic Raman modes of crystals. Micro-Raman measurements on nanostructures with different morphologies offer us a potential way to tailor optical properties of nanostructures by controlling the morphologies of the nanostructures, which is very important for practical applications of nanostructures in thermoelectric devices.     

Resonant enhancement of the formation of hydrogen-helium muonic molecules

Formation of muonic molecules and , where J is rotational quantum number, in electron conversion process is investigated at collision energies between 0.004 eV and 50 eV. Corresponding reaction rates are calculated in adiabatic approximation for the three-body Coulomb problem. Significant enhancement of the rates for and is found near 7 eV and 30 eV, respectively. It is shown that the enhancement is due to resonances present in elastic and scattering at these energies. Acceleration of dμ atoms up to the resonant energy could be realized in triple H-D-³He mixture due to the muon transfer from protium to deuterium. Experimental investigation of nuclear synthesis from molecular state directly formed in the mixture is suggested.     

The 2ν5 overtone bands of perchloryl fluoride

The high-resolution infrared spectra of the monoisotopic species F³⁵Cl¹⁶O₃, F³⁷Cl¹⁶O₃, F³⁵Cl¹⁸O₃ and F³⁷Cl¹⁸O₃ have been studied in the region of the 2ν₅ overtones, from 1100 to 1200 cm⁻¹. Both the parallel and the perpendicular components are clearly observed in the spectra, their origins differing by about 0.4 cm⁻¹. In each spectrum about 2000 transitions have been assigned, 35% of them belonging to . The parallel and perpendicular bands in each manifold have been analyzed separately since no evidence of perturbations has been observed. The rovibration parameters of the v₅ = 2, l₅ = 0 and v₅ = 2, l₅=?2 excited states have been obtained. For the four species combining the and band origins with those of the ν₅ fundamentals the harmonic wavenumbers, , and the x₅₅ and g₅₅ anharmonicity constants have also been derived.     

Vibronic spectra, ab initio calculations, and structures of conformationally non-rigid molecules of oxalyl halides in the ground and lowest excited electronic states. Part I: Reanalysis of the 3680 Å and 4100 Å absorption systems of oxalyl chloride

The vapor-phase absorption spectrum of oxalyl chloride in the 3000-4180 Å region has been re-examined at high resolution. Singlet-singlet and singlet-triplet electronic transitions of the trans-conformer found in the spectrum are in agreement with earlier works [W.J. Balfour, G.W. King, J. Mol. Spectrosc. 26 (1968) 384-397; ibid. 27 (1968) 432-442]. Torsion levels of trans-oxalyl chloride in the ground and excited and states were found for the first time. Ab initio calculations of structures for conformers of oxalyl chloride in the ground and lowest excited electronic states explain the absence of second conformer transitions in the vibronic absorption spectrum.     

Quantum critical behaviour in doped Y bB12 studied by ab initio calculations

The Kondo insulator Y bB₁₂ is known to undergo a transition to the metallic state with doping or under an external magnetic field. Within the virtual crystal approximation (VCA), we calculated the occupation of the Yb 4f and 5d shells, and , as a function of doping of Y bB₁₂ with the rare earths Tm and Lu. We found that exhibits an anomalous change at the critical concentration of the dopant, in agreement with experiment ( for Y b_1−xLu_xB₁₂ and for Y b_1−xTm_xB₁₂). We suggest that the critical behaviour seems to be strictly connected with the change of and in consequence the change of the Yb valency.     

MRCI studies on the electronic structure of AlN and AlN, and the electron affinity of AlN

Using multireference configuration-interaction methods and double to triple-zeta basis sets with semidiffuse and polarization functions, potential energies and spectroscopic constants for low-lying doublet, and quartet states of AlN⁻ were calculated. has R_e=3.280 bohr and . lies 0.17 eV above the ground state. Using an estimated electron affinity of 2.1 eV for AlN, four states of AlN⁻ are found to be stable, namely , , , and . Comparisons with the isovalent anions BN⁻ (three stable states) and AlP⁻ (seven stable states) are made. Photo-detachment of an electron from the state of AlN⁻ can lead to an accurate determination of the energy difference between the two close-lying lowest states of AlN, and , predicted here to be 0.09 eV apart.     

Observation of room temperature photoluminescence in proton irradiated SrTiO3 single crystal

We have irradiated SrTiO₃ single crystal with 3 MeV-proton (H⁺) beam and found that blue -, green - and infrared - frequency photoluminescence (PL) are induced simultaneously at room temperature. TEM and EELS analyses show that an oxygen-deficient amorphous layer is formed at the crystal surface by the proton irradiation. Possible origin of the PL-effect is discussed.     

Absorption spectra of AsH2 radical in 435-510 nm by cavity ringdown spectroscopy

The absorption spectra of jet-cooled AsH₂ radicals were recorded in the wavelength range of 435-510 nm by cavity ringdown spectroscopy. The AsH₂ radicals were produced by pulsed DC discharge in a molecular beam of a mixture of AsH₃, SF₆, and argon. Seven vibronic bands with fine rotational structures have been identified and assigned as the , , and (n = 1-3) bands of the electronic transition. Based on the previous studies of AsH₂ radical, rotational assignments and rotational term values for each band were obtained, and the molecular parameters including vibrational constants, rotational constants, centrifugal distortion constants, and spin-rotation interaction constants were also determined.     

The magnetocaloric effect and low temperature specific heat of SmNi

The magnetocaloric effect (MCE) in a magnetic SmNi sample was evaluated from magnetization and heat capacity measurements. The MCE phenomena in the vicinity of magnetic phase transitions in terms of magnetic entropy change, , and adiabatic temperature change, , are reported. Isothermal magnetization measurements at several temperatures around the transition were carried out and used for versusT calculations. A similar dependence of the magnetic entropy change was evaluated from heat capacity C_p(T) measurements under zero field and 5 T. The SmNi system provides magnetic refrigerants that induce an adiabatic cooling of about during the magnetization process with a field of 5 T in the temperature range of 35-45 K. The temperature dependence of C_p(T) is analyzed in terms of the magnetic and the lattice contributions.     

Prospects of reactor neutrino experiments

Since the energy of a reactor neutrino is a few MeV, all , and oscillations are accessible by reactor neutrino experiments. KamLAND observed the oscillation and currently Double Chooz, RENO and Dayabay experiments are under construction aiming to detect oscillation. There are still good prospects for future reactor neutrino experiments after them. For example, there is room to further improve sin²2θ₁₃ accuracy at a baseline of ∼1.5 km, a very precise sin²2θ₁₂ measurement and the determination of mass hierarchy may be possible at a baseline ∼50 km, and if KamLAND is enlarged to the SuperKamiokande size, better measurement of and sin²2θ₁₂ will be anticipated. It is important to take into account such possibilities when planning future neutrino program after θ₁₃ is measured by current experiments.     

Terahertz spectroscopy of oxygen, O2, in its Σg and Δ electronic states : THz Spectroscopy of O2

High precision rotational spectra of isotopic oxygen O₂ (with or ) in its electronic ground state have been measured in selected frequency regions between 0.4 and 2.0 THz. The main isotopic species, , was also investigated in its first excited electronic state . The new data, analyzed together with previous measurements, yielded improved spectroscopic parameters.     

Reassignment of the C-Cl stretching frequency in the Ã(A″) state of CBrCl

In a recent theoretical paper, vibrational frequencies were reported for CBrCl in the and à states. These values agree well with our previously published experimental frequencies, except in the case of , where the theoretical value of 968.3 cm⁻¹ is significantly higher than the experimental value of 712.6 cm⁻¹. This discrepancy prompted a re-examination of the assignments for transitions involving ν₁ in the laser induced fluorescence spectrum. If the progression ν₁ + nν₂ has the assignment of n reduced by 1 (the origin is not observed), a new experimental value of results. The close accord with the theoretical value lends weight to this re-assignment. Consequently we propose that the experimental frequency be changed to .     

Strong correlation effects and new phase transition at high pressure-low temperature in La0.5Ba0.5FeO3

The physical properties of La_0.5Ba_0.5FeO₃ perovskite have been investigated. The resistivity and magnetism change at around the charge disproportionation temperature. The ferromagnetic cluster-glass state appears when . Under 5 kbar pressure a new phase transition at 5.5 K is found in the magnetization measurement. The transition temperature increases with the increase of the applied pressure. It is suggested that this transition is induced by the spin state transition from to with the pressure increase.     

Near infrared emission spectrum of HCN

The emission spectrum of H¹³CN at 1370 K has been recorded with a hot gas high resolution FT-IR emission apparatus [1] in the wavenumber region of with a resolution of . This work reports the analysis of 50 subbands for the H¹³CN isotopologue of hydrogen cyanide in the 2ν₁ wavenumber region. 23 rovibronic states of H¹³CN including the rovibronic states at have been characterized for the first time and for seven other states it was possible to improve the existing spectroscopic constants substantially. The dense emission spectrum was analyzed with the spectrum analysis software SyMath™ implemented in the Mathematica™ computer algebra system [1].     

A general formula of two-dimensional Franck-Condon integral and the photoelectron spectroscopy of sulfur dioxide

We derived a general formula of Franck-Condon integral for two-dimensional harmonic oscillators () taking into account the Duschinsky effect and applied it to study the photoelectron spectroscopy of SO₂ and . The equilibrium geometries and harmonic vibrational frequencies of , SO₂ and were calculated by using the density functional theory (B3LYP functional) and the coupled cluster singles and doubles with perturbative triples [CCSD(T)] methods with various basis sets up to 6-311+G(3df) and aug-cc-pVTZ. The adiabatic ionization energy and electron affinity were computed by using the CCSD(T) method extrapolated to the complete basis set limit with aug-cc-pVXZ (X = D, T, Q, 5). The simulated photoelectron spectra of both SO₂ and are in accord with the experiment. While the Duschinsky effect plays a role for some weak transitions of SO₂, it can be neglected for . A splitting observed in the experimental photoelectron spectrum of SO₂ is interpreted as contributing from hot bands and combination bands of ν₁ and ν₂, rather than arising from perturbation of a potential barrier as previous researchers proposed. The calculated adiabatic ionization energy and electron affinity are in agreement with the experiment within 0.027 and 0.040 eV, respectively.