High-resolution emission spectroscopy of the AΠ–XΣ system of AlH

The emission spectrum of the A²Π–X²Σ⁺ system of the AlH⁺ ion was investigated in the range of 27 000–29 000 cm⁻¹ by using a conventional spectroscopic technique. The AlH⁺ molecules were formed and excited in an aluminium hollow-cathode lamp with two anodes, filled with a mixture of Ne carried gas and a trace of NH₃. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. The full rotational structure of the 0-0 and 1-1 bands has been observed for the first time (12 branches up to J″ = 36.5) and many new constants of the X²Σ⁺ state have been derived from the analysis. For the A²Π, v = 0 and 1 state a considerable irregularities of the Λ-doubling have been observed. The most reasonable explanation for this anomaly is an interaction with unstableness rotational levels of X²Σ⁺ state and perturbing of the A²Π state by the nearly lyingB²Σ⁺ state.     

Hyperfine coupling constants of cesium 7D states using two-photon spectroscopy

Doppler-free two-photon transitions of cesium 6S_1/2→7D_{3/2, 5/2} were observed in a thermal stabilized cell. A repeated spectrum of 75 MHz introduced from the side band of an electro-optical modulator served as a frequency marker to improve the accuracy of frequency measurement. The hyperfine magnetic dipole constant A and electrical quadrupole constant B of Cs 7D_{3/2, 5/2} can be derived from the splitting intervals of the observed spectra. The results are: A=7.36(07) MHz, B=−0.88(87) MHz for the 7D_3/2 state, and A=−1.81(05) MHz, B=1.01(1.06) MHz for the 7D_5/2 state. These coefficients are improvements for testing high-precision measurements and determining fundamental physical constants.     

Unravelling the visible spectrum of strontium monomethoxide

The bands of the A²E–X²A₁ and B²A₁–X²A₁ electronic transitions of SrO¹²CH₃ and the B²A₁–X²A₁ transition of SrO¹³CH₃ have been recorded at high resolution using a laser ablation jet source. The optical–optical double resonance population depletion technique was used to facilitate the assignment of the spectra. Rotational levels with K = 0, ±1 in the X²A₁ and B²A₁ states and K = 0, 1 and 2 in the A²E state have all been characterised. A perturbation affecting the B²A₁ state caused a reversal of the ordering of the spin-rotation components, F₁ and F₂, in the SrO¹²CH₃ isotopologue. This required the introduction of a modified rotational constant B_mod, affecting only the K = 1, F₂ component of the B²A₁ state, in order to model the SrO¹²CH₃ data in a global fit of the A²E–X²A₁ and B²A₁–X²A₁ transitions.     

Infrared spectra of acetylene dimers and acetylene–nitrogen: (DCCD)2, H-bonded DCCD–HCCH, and DCCD–NN in the 4.1 μm region

Infrared spectra of the weakly-bound T-shaped acetylene dimers DCCD–DCCD and DCCD–HCCH are studied in the region of the DCCD ν₃ fundamental (∼2440 cm⁻¹) using a pulsed supersonic slit-jet expansion and a tunable diode laser probe. The K_a = 0 ← 1 and 1 ← 0 subbands, corresponding to the vibration of the DCCD monomer at the “top” of the T, are analyzed. Compared to the analogous spectrum of HCCH–HCCH, the present results are much less perturbed. The tunneling splitting for (DCCD)₂ in the excited state is determined to be 141 MHz, a big reduction from the previously determined ground state value of 424 MHz. The dimer A rotational constants show a large apparent increase upon vibrational excitation, and we discuss whether this increase is real. The linear DCCD–NN complex is also observed as an impurity in the spectrum, and it too is found to be unperturbed, in contrast with HCCH–NN.     

Multi-mode ground state interaction terms in C60-based electron donor-acceptor complexes

Quantum-chemical testing of donor-acceptor properties of binary molecular complexes, related to the singlet state, is suggested as QCh calculations of studied systems and their constituents by using both spin-nondependent (RHF) and spindependent (UHF) versions of the exploited computational tool. The avoided crossing of intermolecular interaction terms of neutral moleculesE _int (A ⁰ B ⁰) and molecular ionsE _int (A ⁺ B ⁻) causes a multi-mode character of the ground state term. The dependence of D-A complex properties on the type of the term, space positions of the term minimum, and the interrelation of the corresponding energies are discussed. The suggested approach has been applied to binary complexes C₆₀+X (X=TAE, TDAE, DMMA, COANP, 2Li, Mg).     

Cantor–Bernstein Theorem for Pseudo-BCK-Algebras

We prove that if A and B are orthogonally σ-complete commutative pseudo-BCK-algebras such that A is isomorphic to a direct factor in B, and also B is isomorphic to a direct factor in A, then A and B are isomorphic. As a consequence we obtain previously known results for MV-algebras (by De Simone, Mundici and Navara), pseudo-MV-algebras (by Jakubík) and lattice-ordered groups (again by Jakubík). Supported by the Research and Development Council of the Czech Government, the research project MSM 6198959214.     

Magnetic and transport properties of monocrystalline<Emphasis Type="Italic">Fe</Emphasis><Subscript>3</Subscript><Emphasis Type="Italic">O</Emphasis><Subscript>4</Subscript>

A monocrystal ofFe ₃ O ₄ is characterized by resistance, magnetoresistance and magnetic measurements in a temperature range from 4.2 K to 350 K and magnetic field-cycling from −9 T to 9 T. The resistance measurements revealed a metal-insulator Verwey transition (VT) atT _v =123.76 K with activation energy E=92.5 meV at T >T _v and temperature-substitute for the activation energy below the VT,T ₀=E/k _B ≈3800 K within 70 K–110K. The magnetotransport results independently verified the VT at 123.70 K, with discontinuous change in the magnetic moment ΔM≈0.21 ΔM≈0.21μ _B and resistance hysteresis, dependent on the magnetic field in a narrow temperature range of 0.4° around theT _v . The magnetic characterization established self consistentlyT _v as ≈123.67 K, the jump in the magnetization at the VT≈0.25μ _B and confirmed, that the magnetocrystalline anisotropy is the main microscopic mechanism responsible for the magnetization of the monocrystal (88%) with additional natural and imposed defects contributing as 12%.     

Exciton transitions in photoluminescence spectra of AIAs/GaAs superlattices

Conclusions The studies performed here have shown that the superlattice samples studied exhibit photoluminescence spectra which agree with the Kronig-Penney model, although in calculating the energies of the radiative transitions it is necessary to take into account the binding energy of the excitons,E _B. Due to the exciton—phonon interaction, the 1HH peak breaks up on the long wavelength side into a Poisson distribution. The energy of the LO phonon so determined is 34 meV. Bands due toD ⁰-A ⁰ andD ⁰X transitions, caused by remaining low-level impurities in the GaAs crystals are also observed. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 61, Nos. 3–4, pp. 241–245, September–October, 1994.     

ΛN Space-exchange effects in thes-shell hypernuclei and Λ 9 Be

Variational Monte Carlo calculations of the ground state separation energiesB _Λ of thes-shell hypernuclei and also of _Λ ⁹ Be have been made for an Urbana-type central space-exchange ΛN potential consistent with Λp scattering, and also including three-body ΛNN forces. Thes-shell hypernuclei are treated asA-body systems (A = baryon number), and _Λ ⁹ Be is analysed as a partially nine-body problem in the Λ — 2α model. The reduction ofB _Λ due to the space-exchange ΛN potential has been calculated for thes-shell hypernuclei for a range of interactions: both ΛN and ΛN + ΛNN forces. ForA = 3,4,5 the exchange energy is approximately, 0.04, 0.15 and 0.50 MeV, respectively. For _Λ ⁹ Be a much more limited study gives ≅ 1.3 MeV. These values are much larger than that for ‘soft’ ΛN +NN potentials when the correlations are weak. Preliminary results were presented at the DAE Symp. on ‘Nuclear Physics’ Vol. 32B (1989).     

Carbon phosphide (B2 Σ + — A2 Π i) band system: RKR Franck-Condon factors andr-centroids

Franck-Condon factors andr-centroids based on Rydberg-Klein-Rees potential have been computed for the CP (B ² Σ ⁺ —A ² Π _i) band system. These results are compared with the Morse values and discussed.     

Structural and Torsional Properties of o-Cresol and o-Cresol-OD as Obtained from Microwave Spectroscopy and ab Initio Calculations

The microwave spectra of o-cresol and of o-cresol-OD were assigned using molecular beam Fourier transform microwave (MB-FTMW) spectrometers in the frequency range of 3-40 GHz. Two conformers of o-cresol were measured where the hydroxy group is syn with respect to the methyl group in one case and anti in the other. The transitions of both conformers were split due to internal rotation of the methyl group. For syn-o-cresol we found the rotational constants A=3249.45242(18) MHz, B=2202.02546(18) MHz, C=1323.66277(16) MHz, and the barrier to internal rotation of the methyl group V₃=7.912(46) kJ mol⁻¹. In the case of anti-o-cresol A=3273.80084(18) MHz, B=2196.26747(18) MHz, C=1325.36424(22) MHz, and V₃=4.4256(14) kJ mol⁻¹ was obtained. Moreover we were able to determine the quartic centrifugal distortion constants, the angle between the internal rotor axes, and the inertial a axes, and, for the deuterated species, additionally the deuterium nuclear quadrupole coupling constants.     

The emission spectrum of the CΣ–XΣ system of AlH

The ultraviolet spectrum of AlH has been investigated at high resolution between 42 000 and 45 000 cm⁻¹ using a conventional spectroscopic technique. The AlH molecules were formed and excited in an aluminium hollow-cathode lamp with two anodes, filled with a mixture of Ne carried gas and a trace of NH₃. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. The 0–0, 1–1 and 1–2 bands of the C¹Σ⁺–X¹Σ⁺ transition have been identified and rotationally analyzed. The new data were elaborated with help of recent X¹Σ⁺ state parameters reported by White et al. [J. Chem. Phys. 99 (1993) 8371–8378] and by Szajna and Zachwieja [Eur. Phys. J. D. 55 (2009) 549–555]. Determined constants of the excited C¹Σ⁺ state include: T_e = 44 675.3711(57) cm⁻¹, ω_e = 1575.3357(42) cm⁻¹, ω_ex_e = [125.5] cm⁻¹, B_e = 6.66804(32) cm⁻¹, α_e = 0.55839(56) cm⁻¹, D_e = 2.23(13) × 10⁻⁴ cm⁻¹, β_e = 6.13(25) × 10⁻⁴ cm⁻¹ and r_e = 1.613132(39) Å. The C¹Σ⁺ state is found to be extensively perturbed in the v = 0 and 1 vibrational level at J = 20, 22 − 27 and J = 5 − 9, respectively. This was probably caused by the interaction with the vibrational levels of the outer minimum.     

Fabrication and electrical characterization of p-Sb2S3/n-Si heterojunctions for solar cells application

Antimony trisulphide (Sb₂S₃) films were prepared by thermal evaporation technique on n-type single crystal Si substrates to fabricate p-Sb₂S₃/n-Si heterojunctions. The electrical transport properties of the p–Sb₂S₃/n-Si heterojunctions were investigated by current–voltage (I–V) and capacitance–voltage (C–V) measurements. The temperature-dependent I–V characteristics revealed that the forward conduction was determined by multi-step tunnelling current and the activation energy of saturation current was about 0.54 eV. The 1/C²–V plots indicated the junction was abrupt and the junction built-in potential was 0.6 V at room temperature and decreased with increasing temperature. The solar cell parameters have been calculated for the fabricated cell as V_oc = 0.50 V, J_sc = 14.53 mA cm⁻², FF = 0.32 and η = 4.65% under an illumination of 50 mW cm⁻².     

Gas-phase detection of discharge-generated DSOD

We report the first spectroscopic detection of perdeuterated 1-oxadisulfane, DSOD, generated in a radio-frequency plasma of D₂S and D₂O. The chain molecule DSOD produces a perpendicular-type spectrum, with well-known spectral features encountered in previous studies of geometrically related molecules, such as compact Q-branches, which are clearly recognizable. The arrangement of the transitions shaping the Q-branches usually provides sufficient proof for a clear-cut detection of a chain molecule such as DSOD. Guided by quantum chemical calculations, we have located the band center of the -branch of DSOD in the frequency region near 466.5 GHz using the Cologne terahertz spectrometer. This -branch displays both b- and c-type spectra, quite analogous to the behavior of the corresponding -branch of HSOH. In addition, we have been able to detect an internal rotational splitting of ∼0.5 MHz for c-type transitions of the -branch, which lends independent support to our present assignment. From the measurements performed on Q-branches, we derive the following differences in rotational constants: A−(B+C)/2=93331.001(15) MHz, and (B−C)/4=172.95923(29) MHz, in excellent agreement with theoretical predictions.     

The size distribution for theA g RB f−g Model of polymerization

This paper gives the equilibrium distribution of polymer sizes for Flory'sA _g RB _f–g model of polymerization. In this model, the polymers are composed of structural units withg functional groups of the typeA and (f-g) functional groups of the typeB. Reaction is subject to three conditions: (1) Functional groups of the typeA react only with those of typeB, and vice versa. (2) Intramolecular reactions do not occur [and therefore only branched-chain (noncyclic) polymers and formed]. (3) Subject to conditions (1) and (2), all functional groups are equally reactive. The derivation employs Stockmayer's statistical mechanical method (first used on Flory'sRA _f model), coupled with a recursion giving the number of distinct polymers which may be assembled fromk units of theA _g RB _f–g type. We also give distributions for a limiting case of theA _g RB _f–g model, the so-calledA _g RB model. This paper completes the solution of the Smoluchowski coagulation equation (monodisperse case) for the kernelsa _ij =A + B(i +j)+ Cij. The proof will be given in another publication.     

Rovibrational constants for the ground state and ν8 = 1 state of ethylene-d3 (C2HD3) by high-resolution FTIR spectroscopy

The Fourier transform infrared (FTIR) spectrum of the ν₈ fundamental band of ethylene-d₃ (C₂HD₃) was recorded with a unapodized resolution of 0.0063 cm⁻¹ in the wavenumber region of 840–980 cm⁻¹. By assigning and fitting a total of 738 infrared transitions using a Watson’s A-reduced Hamiltonian in the I^r representation, rovibrational constants for the upper state (ν₈ = 1) up to all five quartic centrifugal distortion terms were derived for the first time. The root-mean-square (rms) deviation of the fit was 0.00076 cm⁻¹. The ground state rovibrational constants of C₂HD₃ were also determined for the first time by a fit of 450 combination-differences from the present infrared measurements, with rms deviation of 0.00075 cm⁻¹. Local frequency perturbations were not detected in the C-type ν₈ band of C₂HD₃ which is centred at 918.73199 ± 0.00007 cm⁻¹.     

Super B factories

Heavy-flavor physics, in particular B and τ physics results from the B factories, currently provides strong constraints on models of physics beyond the Standard Model. A new generation of colliders, Super B Factories, with 50 to 100 times the luminosity of existing colliders, can, in a dialog with LHC and ILC, provide unique clarification of new physics phenomena seen at those machines.     

Selected topics from Belle

The Belle experiment continues to explore the origin of CP violation and test all aspects of standard model inB meson decays. Recent results on CP violating paramter sin2ф₁ and other measurements are presented.