Identification of new lines in the beam-foil spectrum of B II–IV

Ten, six, and twenty-one new lines appearing in the beam-foil spectra of boron (30–200 nm) have been identified in B II, B III, and B IV, respectively. Energies have been determined with higher accuracy than obtained before for the 2p3s ¹ P ⁰, 2s6d ³ D, 2p3p ³ D, 2p3p ³ S, 2p3p ³ P, and 2p3p ¹ D terms in B II. First energy values are also reported for the 2s6d ¹ D and 2s7d ³ D terms in B II.     

Calculation of the photo-electrons angular distribution asymmetry parameter β2p near the (3s3p)1 P resonance of He*

Near the (3s3p)¹ P resonance of He, we have calculated the photoelectrons angular distribution asymmetry parameter β_2p in the diagonalization approximation. Using the measured value of β _n=2 near the (3s3p)¹ P level obtained by Lindle et al. in the resonance photo-ionization of He to He^?(n=2), we have estimated the ratioR=σ_2p /σ_2s of the partial 2p photo-ionization cross section to the partial 2s photo-ionization cross section. Our calculation supports the result that in the resonance region, the formation of ions in the 2p level dominates over the 2s level. This is in good agreement with the experimental and most of the theoretical results reported to date.     

Equilibrium convoy electron production and charge exchange

RatiosN _2s /N _3p of 2s to 3p populations in hydrogen atoms formed by the passage of protons through carbon foils have been measured using the beam-foil-laser excitation method reported very recently. No dependence ofN _2s /N _3p on the incident proton energyE _p , in the 100–300 keV energy range analysed, is observed. From the ratioN _3p /N _2p of 3p to 2p beam-foil populations in hydrogen reported previously (N _3p /N _2p independent ofE _p forE _p >100 keV) and the ratiosN _2s /N _3p measured in the present work, a mean value ofN _2s /N _2p equal to 0.61±0.04 is deduced. These results are compared with available experimental data.     

Second orderg-Hartree calculations of the dipole-constants of Li and B

A full second orderg-Hartree and HF calculation of the dipole-constants of Li 2s, Li 2p _1/2, B 2p _1/2 and B 2p _3/2 is presented. Both calculations are compared and the breakdown of the methods for different states is discussed.     

Theoretical study of LiK and LiK+ in adiabatic representation

The potential energy curves have been calculated for the electronic states of the molecule LiK within the range 3 to 300 a.u., of the internuclear distance R. Using an ab initio method, through a semiempirical spin-orbit pseudo-potential for the Li (1s ²) and K (1s ²2s ²2p ⁶3s ²3p ⁶) cores and core valence correlation correction added to the electrostatic Hamiltonian with Gaussian basis sets for both atoms. The core valence effects including core-polarization and core-valence correlation are taken into account by using an l-dependent core-polarization potential. The molecular orbitals have been derived from self-consistent field (SCF) calculation. The spectroscopic constants, dipole moments and vibrational levels of the lowest electronic states of the LiK molecule dissociating into K (4s, 4p, 5s, 3d, and 5p) + Li (2s, 2p, 3s, and 3p) in ^{1, 3}Σ, ^{1, 3}Π, and ^{1, 3}Δ symmetries. Adiabatic results are also reported for ²Σ, ²Π, and ²Δ electronic states of the molecular ion LiK⁺ dissociating into Li (2s, 2p, 3s, and 3p) + K⁺ and Li⁺ + K (4s, 4p, 5s, 3d, and 5p). The comparison of the present results with those available in the literature shows a very good agreement in spectroscopic constants of some lowest states of the LiK and LiK⁺ molecules, especially with the available theoretical works. The existence of numerous avoided crossing between electronic states of ²Σ and ²Π symmetries is related to the charge transfer process between the two ionic systems Li⁺K and LiK⁺.     

Classification of 3-3 transitions in neonlike germanium in laser-produced plasma

Classification of 3-3 transitions in neonlike germanium in laser-produced plasma has been made. The spectra have been observed in the range of 185–290 Å using a high resolving power (λ/Δλ ～ 13000) grazing-incidence spectrometer in XUV laser experiment. A total of 21 lines (including five lasing lines) have been classified as transitions between the 2s ²2p ⁵3s, 3p, 3d or 2s2p ⁶3p, 3d and sodiumlike germanium configurations. The identified transitions have been used to derive energy levels of 2s ²2p ⁵3l in neonlike germanium. The experimental results have been compared with theoretical predictions from Dirac-Fock (MCDF) calculations.     

Photoionization of highly excited atomic sodium involving core-excited resonances

Resonant photoionization in thenl outer-shell of 2p ⁶ nl excited sodium is studied between 32.50 and 33.50 eV. Resonances are of the type 2p ⁶ nl → 2p ⁵ 3snl → 2p ⁶ ελ, i.e. corresponding to the excitation of a 2p core-electron to a 3s orbital. Experimental technique combines laser and synchrotron radiation for exciting sequentially sodium atoms. The main features of the resonances — energies and total oscillator strengths — are measured or estimated. From the results, one concludes that the valence electron is almost decoupled from the core, with respect to the core excitation.     

Determination of configuration-dependent spin-orbit interaction constants by atomic spectroscopy

A new approach to the evaluation of spin-orbit interaction (SOI) constants is presented. The SOI constants ξ_p and ξ_d of 4p and 3d electrons have been evaluated by employing the available atomic spectral data for the first transition row atoms and ions possessing the electron configuration K(2)L(8)3s²3p⁶3d^α4s^β4p^γ.     

Beam-foil lifetime study of then=3 complex in al-like Ti9+

The beam-foil spectrum obtained using a beam of Ti³⁺ ions of energy 10 MeV has been studied over the wavelength range from 14 nm to 80 nm. New assignments are suggested for 18 levels belonging to the levels of the 3p ³, 3s 3p 3d and 3s ² 4p configurations. The lifetimes of these levels, as determined from conventional multi-exponential curve fitting of their intensity decay curves, are typically about 30% longer than is forecast by theory. The same decay curves have also been used to represent the effect of cascade repopulation on the decay curves obtained for the resonance doublet levels of the 3s 3p ² and 3s ² 3d configurations. A discussion is given of the possible techniques for cascade correction in beam-foil lifetime measurements, and of the inclusion of a window function to represent the vignetting effect close to the foil. Lifetimes obtained using these techniques for the 3s ² 3d levels (38±6 ps for J=3/2, 36±5 ps for J=5/2), and the 3s3p ^{2 2} S level (99±6 ps),² P levels (60±15 ps for J=1/2, 50±15 ps for J=3/2) and² D levels (820±30 ps for j=3/2, 870±40 ps for J=5/2) are in good agreement with theoretical predictions.     

Synthesis of oligosaccharides as potential novel food components and upscaled enzymatic reaction employing the β-galactosidase from bovine testes

The β-galactosidase from bovine testes (EC 3.2.1.23) promotes the transfer of a galactose unit to glucose or galactose-containing residues in manifold derivatives, establishing β1→3 linkages.The synthesis of several potentially biologically important oligosaccharides β-d-Galp-(1→3)-α-d-Glcp-(1→2)-β-d-Fruf2, β-d-Galp-(1→3)-β-d-Galp-(1→4)-α,β-d-Glcp4, β-d-Galp-(1→3)-α-d-Glcp-(1→4)-d-Glcp-ol/Manp-ol 6, β-d-Galp-(1→3)-α-d-Glcp-(1→6)-β-d-Fruf8, β-d-Galp-(1→3)-α-d-Glcp-(1→6)-[α-d-Glcp-(1↔2)]-β-d-Fruf10, α-d-Galp-(1→6)-[β-d-Galp-(1→3)]-α-d-Glcp-(1↔2)-β-d-Fruf12, β-d-Galp-(1→3)-α-d-Glcp-(1↔2)-β-d-Fruf-(1↔2)-β-d-Fruf14 has been reached in yields between 7 and 44% by implementation of this specific enzyme. In addition, we found that it is feasible to gain high yields without an enzyme-specific buffer and even making upscaled preparation on a gram scale.     

Ab initio structure of 3p4p in Si I

Multiconfiguration calculations have been performed in order to estimate ab initio energies for the configuration 3p4p in Si I. A preliminary attempt has also been made to calculate E2 transition rates for transitions from levels of 3p ² to those of 3p4p. However, these rates show a gauge dependence, which indicates that further correlation needs to be included to obtain accurate rates and lifetimes.     

Beam-foil lifetime study of neon-like Ti12+

Decay curves of almost all 2p ⁵ 3p and 2p ⁵ 3d levels of Ti¹²⁺ for which the Δn=0 decay branch is of importance have been recorded. The data have been analyzed by multiexponential fitting and by cascade model simulations. The results of both approaches agree and support the calculations by Fawcett for most of the levels.     

Redox potentials of dopamine and its supramolecular complex with aspartic acid

Dopamine (DA) can be oxidized to dopamine quinone (DAquinone) through a one-step, two-electron redox reaction. The electron transfer property of DA and its supramolecular complex with aspartic acid (Asp) has been investigated by the theoretical calculations. We calculated the standard redox potentials (E ^o) of DA/DAquinone at the MP2/6-31G(d,p)//B3LYP/6-31G(d,p), MP2/6-31+G(d,p)//B3LYP/6-31+G(d,p), MP2/6-31G(d,p)//B3LYP/6-311G(d,p), and MP2/6-311+G(d,p)//B3LYP/6-311+G(d,p) levels. Comparing the experimental value, the redox potentials of DA/DAquinone obtained at MP2//B3LYP/6-311G(d,p) and MP2//B3LYP/6-311+G(d,p) levels can be considered as the upper and lower estimates. DA can form supramolecular complex (DA-Asp) with Asp through hydrogen bond (H-bond). Therefore, the values of 0.631 and 0.628 V obtained at MP2//B3LYP/6-311G(d,p) and MP2//B3LYP/6-311+G(d,p) levels for DA-Asp/DAquinone-Asp can be proposed as the upper and lower estimates of a probable (about 0.630 V) value of the corresponding redox potential. The calculated E ^o values of DA-Asp/DAquinone-Asp at the four theoretical levels are upper than those of DA/DAquinone, which indicates that the formation of H-bonds weaken the electron-donating ability of DA.     

Structural analysis of several W(VI) and Mo(VI) complex perovskites prepared by the polymeric precursors method

We describe in this work the synthesis by the Pechini method of five Mo(VI)- and W(VI)-containing complex perovskites and their structural characterisation by HREM and XRD. The compounds studied, Ba(B_2/3′B_1/3″)O₃ (B′=In and Y; B″=W and Mo) and Sr(In_2/3W_1/3)O₃, were obtained after firing the precursor powders for 8 h at 1200°C. Thermal analysis showed that the formation mechanism of the five perovskites is similar and implies the formation of barium carbonate and barium tungstates or molybdates of different stoichiometries as intermediate phases. Interesting enough, these similar mechanisms yield to materials of a quite different structure. Indeed, Ba(In_2/3Mo_1/3)O₃ and Sr(In_2/3W_1/3)O₃ were found to be disordered perovskites (unit cells: a_p×a_p×a_p and , respectively); on the other hand, two phases coexist in the sample Ba(In_2/3W_1/3)O₃ at the synthesis conditions: an ordered predominant phase (unit cell: 2a_p×2a_p×2a_p) and, as a minor phase, a disordered perovskite (unit cell: a_p×a_p×a_p). Finally, the two yttrium-containing compounds were found to be ordered perovskites (2a_p×2a_p×2a_p).     

Intercombination lines of Mg I-, Al I- and Si I-like ions in the beam foil spectra of Ti,Fe, Ni and Cu

In delayed spectra of foil-excited beams of Ti, Fe, Ni and Cu ions lines have been observed which are identified with intercombination transitions 3s ^{2 1} S ₀ — 3s 3p ³ P ₁ ⁰ , 3s ² 3p ² P ⁰ — 3s 3p ^{2 4} P and 3s ² 3p ^{2 3} P — 3s 3p ^{3 5} S ₂ ⁰ in magnesiumlike, aluminiumlike and siliconlike spectra, resp. Wavelengths and decay properties have been determined. The results are compared to recent theoretical predictions.     

X-ray photoelectron spectra of polynuclear manganese complexes

Manganese trimethylacetate complexes with different ligand environments were studied by X-ray photoelectron spectroscopy (XPS). Changes in the Mn 2p, C 1s, O 1s, and N 1s X-ray photoelectron spectra caused by the substitution of Mn → N coordination bonds for Mn → O coordination bonds were examined. In the spectra of manganese trimethylacetate complexes, the satellite component was identified, which is evidence of the high-spin state of manganese atoms. An increase in the magnetic moment of the manganese complexes, both with the oxygen and mixed oxygen-nitrogen environment, is accompanied by an increase in the spin-orbit splitting, the difference in E _b between the satellite and the Mn 2p _3/2 line, and the ratio between the integrated intensities of the satellite and the Mn 2p _3/2 line (I sat_3/2/I Mn 2p _3/2). The XPS data made it possible to determine the measure of covalence of the metal-ligand bond. The XPS results are consistent with X-ray crystallography data.     

Two-photon ionization of an inner shell electron of the Cl atom

We have calculated, using second order perturbation theory, the two photon ionization cross section of a K-shell electron of chlorine forE=1.6 keV incident photons. Two classes of intermediate states must be considered, those in which a 1s electron moves to an emptyp-orbital, and those in which an electron from an occupiedp-orbital moves into the continuum. The first class of intermediate states is followed by the ejection of ap-electron into the continuum. The second class of intermediate states is followed by the transfer of a 1s electron into an emptyp-state. The largest contribution comes from 3p →d-continuum followed by 1s → 3p transition. Our result is σ⁽²⁾/I=2.06×10⁴¹ cm⁴/W where σ⁽²⁾ is the two photon ionization cross-section andI is the light intensity.     

Rhodium-catalyzed alkylation of aromatic azines with alkenes via C-H bond activation

The aromatic azines reacted with terminal alkenes under a rhodium catalyst [RhCl(coe)₂]₂ and Cy₃P to give the alkylated products with good to high isolated yields. The azines bearing H and o-CH₃, p-CH₃ and p-CH₃O groups have high reactivities, but m-CH₃O, p-Cl, p-F exhibit low reactivities.     

Organosilicon compounds : LI. Further studies of the base-catalysed solvolysis of N-(triorganosilyl)anilines

Relative rates of solvolysis of some N-triorganosilylanilines in mixtures of ethanol and aqueous potassium hydroxide have been determined, with results as follows. (i) For XC₆H₄NHSiEt₃ compounds in MeOH (5 vol) + aq. alkali (2 vol) at 50°: (X =) H, 1.0;p-Me, 0.80;p-OMe, 0.83;m-Me, 0.90; o-Me, 0.87; p-SMe, 1.90; p-F, 1.7; p-Cl, 2.8; o-Cl, 14; m-Cl, 4.2; m-NO₂, 18; p-CN, ca. 43; p-NO₂, ca. 120. (ii) For PhNHSi(C₆H₄Y)₃ compounds in MeOH (10 vol) + aq. alkali (1 vol) at 50°: (Y =) H, 1.0; p-OMe, 0.12; p-Cl, ca. 32; m-Cl, ca. 84. (iii) For PhNHSiR₃ compounds in MeOH (5 vol) + aq. alkali (2 vol) : (R₃ =) Et₃, 1.0; Et₂Me, 18 (at 30°); Me₂-i-Pr, 8 (at 30°);Me₂-t-Bu, 0.012 (at 50°);i-Pr₃, 0.006 (at 50°). In series (i) the relative rates correlate with σ, or where appropriate σ^?-constants, with a ? value of 1.6. It is suggested that in the transition state of the rate-determining step the OSi bond is fully formed, or almost so, the SiN bond approximately 20—50% broken, and the bond between the nitrogen atom and a proton from the solvent ca. 10—30% formed.     

Parametric investigation of the isotope shift in odd configurations of Ne i

Isotope shift measurements were performed on 33 transitions of Ne i by means of optogalvanic and intermodulated optogalvanic spectroscopy as well as saturation absorption spectroscopy. Using a large number of line isotope shift values obtained from both literature and our measurements, the level isotope shifts were calculated with improved concistency. Fine structure calculations were performed in odd configurations in order to obtain isotope shift parameters by means of the parametric method, 2p ⁵ 3s: g1 = -1077.5(7), z _2p = 15.3(3), 2p⁵5 s: g ₁ = -104(26), z _2p = 14(6), 2p ²4d: g ₁ = -42(6), z _2p = 17(3).