Dark resonance of Cs atoms velocity-selected in a thin cell

We carried out experimental and theoretical research on dark Raman resonances in the absorption of the probe monochromatic wave in a thin vapor cell, whose length is much less than the diameters of probe and coupling laser beams. In this case, only the slow atoms have enough time to settle down to the dark quantum state during a free flight between the end walls of the cell. As a result, a sub-Doppler structure is observed when one sweeps both the coupling and probe laser frequencies keeping the Raman resonance condition. Second harmonic lock-in detection is used to evaluate sharpness of the dark-resonance line. The cell-length dependence of the observed spectral profile is satisfactorily reproduced by the steady-state analysis of the density matrix in which the velocity-dependent transit time effect is taken into account.     

Behavior of Boron Implanted in Semiconductor Si

Using β-NMR with ¹²B nuclei the temperature dependence of the lattice locations of boron implanted in Si is studied. At low temperature almost 100% of the implanted B is in either substitutional site or nonsubstitutional site. Above 260 K, the nonsubstitutional B rapidly becomes undetectable and disappears at a temperature higher than 325 K due to the fast spin-lattice relaxation. Above 450 K, the fraction of substitutional B increases to 100%. These experimental results are consistently explained by the thermal atomic jump and the dissociation of the defect associated with the nonsubstitutional B. This revised version was published online in September 2006 with corrections to the Cover Date.     

Every non-Euclidean oriented matroid admits a biquadratic final polynomial

Richter-Gebert proved that every non-Euclidean uniform oriented matroid admits a biquadratic final polynomial. We extend this result to the non-uniform case.     

Hyperfine Interactions of N Isotopes in TiO2 and Quadrupole Moment of 16N

Hyperfine interactions of ^12,14N in BN(hexagonal) crystal were studied by detecting β-NQR(¹²N) and FT-NMR(¹⁴N). A β-NMR of ¹⁶N (I ^π=2⁻,T _1/2=7.13 s) in MgO crystal was detected to determine the magnetic moment of ¹⁶N to be |μ(¹⁶N:2⁻)|=(1.986±0.001)μ_N. Also, the β-NQR of ^12,16N in TiO₂ crystal were detected to determine |Q(¹⁶N:2⁻)|=(17.9±1.7) mb. An abnormally small effective charge for neutrons is required to account for |Q(¹⁶N:2⁻)|. This revised version was published online in September 2006 with corrections to the Cover Date.     

Redox reactions of nitrite ions on the surface of colloidal magnetite particles coated with chondroitin sulfate

Colloidal magnetite particles coated with chondroitin sulfate (abbreviated as Fe/CS) were prepared under conditions of varying Fe(II) fractions at a fixed Fe concentration and a given concentration of CS. The average size of the magnetite core region was estimated as 7 nm from transmittance electron microscopy measurements, while the size of the Fe/CS particles ranged 155–175 nm, as estimated using Rayleigh scattering measurements by reference to a control size derived from the dynamic light scattering. The reaction of various Fe/CS with NO⁻ ₂ in aqueous solutions was determined by fluorometry using 2,3-diaminonaphthalene as a probe and by gas chromatography–mass spectrometry. The concentrations of NO⁻ ₂ in the reaction mixtures decreased in the presence of Fe/CS to a greater extent under Ar compared with aerobic conditions. The reactivity of Fe/CS toward NO⁻ ₂ under aerobic conditions increased with decreasing the size of Fe/CS particles or with increasing content of Fe(III) in the Fe/CS solutions, but was independent of the Fe(II) fraction in the preparation process. While CS molecules had no influence on the NO⁻ ₂ decomposition, those coated with the magnetite core may prevent the diffusion of NO⁻ ₂ to be adsorbed on the core surfaces. NO⁻ ₂ was concluded to undergo redox reactions with Fe(II) and Fe(III) located on the core surface of magnetite crystalline structures of Fe/CS. Received: 12 April 2000/Accepted: 9 August 2000     

A polynomial case of unconstrained zero-one quadratic optimization

Unconstrained zero-one quadratic maximization problems can be solved in polynomial time when the symmetric matrix describing the objective function is positive semidefinite of fixed rank with known spectral decomposition. Received: August 2000 / Accepted: March 2001?Published online May 18, 2001     

Electronic processes in NO dimerization on Ag and Cu clusters: DFT and MRMP2 studies

Experimentally observed NO dimerization on Cu and Ag surfaces is surprising because binding energy of NO dimer is very small in gas phase. MRMP2, MP2 to MP4, CCSD(T), and DFT studies of NO dimerization on Ag₂ and Cu₂ clusters disclosed that the CCSD(T) method could be applied to this reaction on Ag₂ and Cu₂ unlike NO dimerization in gas phase which exhibits significantly large nondynamical electron correlation effect. Charge-transfer (CT) from Ag₂ and Cu₂ to NO moieties plays important role in N N bond formation between two NO molecules. This CT considerably decreases nondynamical correlation effect. Also, the DFT method could be applied to this NO dimerization, if appropriate DFT functional is used; all pure functionals examined here and most of the hybrid functionals underestimated the activation barrier (E_a), while only ωB97X provided E_a similar to CCSD(T)-calculated value. NO dimerization on similar Cu₂ and Cu₅ needs moderately larger E_a than those on Ag₂ and Ag₅, because frontier orbital participating in the CT exists at lower energy in Cu₂ and Cu₅ than in Ag₂ and Ag₅. The E_a decreases in the order Ag₂ >> Ag₃₈ > Ag₇ ∼ Ag₅ and the reaction energy (ΔE) is positive (endothermic) in Ag₂ but significantly negative in Ag₃₈, Ag₇, and Ag₅, indicating that various Ag clusters could be effective for NO dimerization except for Ag₂. The decreasing order of E_a and increasing order of exothermicity are attributed to increasing order of the frontier orbital energy of Ag₂ < Ag₃₈ < Ag₇ ∼ Ag₅. © 2018 Wiley Periodicals, Inc.