Theoretical study on 2s2p^6np Rydberg states of Cu^19＋ ion

We report on the calculations of transition wavelengths and weighted oscillator strengths for 2s 2 2p 6-2s2p 6 np （4≤n≤20） electric dipole （E1） transitions of Cu 19+ ion.The flexible atomic code （FAC） has been adopted for the calculations.Comparisons are made with the experimental data available,showing that the present results for 4 ≤n≤6 are more accurate than the previous calculated values.Furthermore,combining the quantum defect theory （QDT） with the transition energies of 2s22p～6-2s2p～6np,the quantum defects for 2s2p 6 np Rydberg series of Cu～（19+）ion are determined.In addition,the energies of any highly excited states （n>20） for this series can be reliably predicted using the QDT and the given quantum defects.The ionization energies for Cu¹⁹⁺ and Cu²⁰⁺ ions are also calculated and they excellently accord with previous experimental and calculated values.     

Transition energy and dipole oscillator strength of 1s23d- 1s2nf transitions for Sc18+ ion

The transition energies of the 1s²3d-1s² nf (4⩽n⩽9) transitions and fine structure splittings of 1s² nf (n⩽9) states for Sc¹⁸⁺ ion are calculated with the full-core plus correlation method. The quantum defect of 1s² nf series is determined by the single-channel quantum defect theory. The energies of any highly excited states with n⩾10 for this series can be reliably predicted using the quantum defect as function of energy. Three alternative forms of the dipole oscillator strengths for the 1s²3d-1s² nf (n⩽9) transitions of Sc¹⁸⁺ ion are calculated with the transition energies and wave functions obtained above. Combining the quantum defect theory with the discrete oscillator strengths, the discrete oscillator strengths for 1s²3d-1s² nf (n > 9) transitions and the oscillator strengths densities corresponding to the bound-free transitions are obtained. __________ Translated from Chinese Journal of Atomic and Molecular Physics, 2005, 22(4) (in Chinese)     

Wavelength and oscillator strength of dipole transition 1s<Superscript>2</Superscript>2p—1s<Superscript>2</Superscript><Emphasis Type="Italic">n</Emphasis>d for Mn<Superscript>22+</Superscript> ion

The transition energies, wavelengths and dipole oscillator strengths of 1s²2p—1s² nd (3⩽n⩽9) for Mn²²⁺ ion are calculated. The fine structure splittings of 1s² nd (n</9) states for this ion are also evaluated. In calculating energy, the higher-order relativistic contribution is estimated under a hydrogenic approximation. The quantum defect of Rydberg series 1s² nd is determined according to the quantum defect theory. The results obtained in this paper excellently agree with the experimental data available in literatures. Supported by the National Natural Science Foundation of China (Grant No. 10774063)     

Energy and Oscillator Strength of V20+ Ion

The ionization potentials and fine structure splittings of 1s² nl (l = s, p, and d; n ⩽ 9) states for lithium-like V²⁰⁺ ion are calculated by using the full-core plus correlation (FCPC) method. The quantum defects of these three Rydberg series are determined according to the single-channel quantum defect theory (QDT). The energies of any highly excited states with n ⩾ 10 for these series can be reliably predicted using the quantum defects that are function of energy. The dipole oscillator strengths for the 1s²2s–1s² np and 1s²2p–1s² nd (n ⩽ 9) transitions of V²⁰⁺ ion are calculated with the energies and FCPC wave functions obtained above. Combining the QDT with the discrete oscillator strengths, the discrete oscillator strengths for the transitions from the given initial state to highly excited states (n ⩾ 10) and the oscillator strength density corresponding to the bound-free transitions are obtained. Translated from Chinese Journal of Atomic and Molecular Physics, 2005(2) (in Chinese)     

STUDIES ON COPPER-CONTAINING NAD GLYCOHYDROLASE FROM AGKISTRODON ACUTUS VENOM BY FLUORESCENCE AND CD SPECTROSCOPY

ABSTRACT

The properties of NAD Glycohydrolase (NADase), purified from Agkistrodon acutus venom, have been studied by fluorescence and CD spectroscopy. The fluorescence intensities of NADase decrease by about 1% or 3% when the concentrations of I^? ion are 0.1 mol/L or 0.2 mol/L in the NADase solutions, respectively. However, the fluorescence intensities of the NADase are quenched by about 25% and 48%, respectively, with further addition of 1 mmol/L EDTA into solutions. CD spectra also suggested that EDTA could remove Cu²⁺ ion from NADase molecule and the conformation of NADase changed much. So Cu²⁺ ion is very important to maintain the geometrical structure of NADase.     

Quinoline group grafted carbon nanotube fluorescent sensor for detection of Cu ion

A carbon nanotube-based fluorescent chemosensor MWNTs-glycine-N-8-quinolylamide (MWNTs-GNQ) has been designed and synthesized. Steady-state fluorescence emission studies showed that this material displays high selectivity and sensitivity for the Cu²⁺ ion over other cations such as Zn²⁺, Cd²⁺, Mg²⁺, Ca²⁺, and Ni²⁺.     

Optical characterization of Cu ion-doped zinc lead borate glasses

We have developed a new series of zinc lead borate (ZLB) glasses by varying ZnO content, to enhance UV transmission, in the chemical composition of xZnO-15PbO-(85−x)B₂O₃, where x=0, 5, 10, 15, 20, 25, 30, 35, 40 and 45 mol% ZnO. From the measurement of UV absorption spectra both the direct and indirect band gaps have been evaluated. Also different physical properties of a reference glass of 45ZnO-15PbO-40B₂O₃ have been studied. From the measurement of refractive indices at six different wavelengths, Cauchy's constants (A=1.578743209; and ) have been computed and a satisfactory correlation has been achieved between the theoretical and the experimental results. Absorption spectra of Cu²⁺(45−x)ZnO-15PbO-40B₂O₃ (where x=0.1, 0.2, 0.5 and 1.0 mol%) have shown two absorption bands at 428 nm (²B_1g→²E_g) and 777 nm (²B_1g→²B_2g). Emission spectra of (1.0 mol%) Cu²⁺:ZLB have revealed two emission transitions at 400 and 493 nm with excitations at 288 and 316 nm.     

Insights into copper coordination in the EcoRI–DNA complex by ESR spectroscopy

The EcoRI restriction endonuclease requires one divalent metal ion in each of two symmetrical and identical catalytic sites to catalyse double-strand DNA cleavage. Recently, we showed that Cu²⁺ binds outside the catalytic sites to a pair of new sites at H114 in each sub-unit, and inhibits Mg²⁺-catalysed DNA cleavage. In order to provide more detailed structural information on this new metal ion binding site, we performed W-band (～94 GHz) and X-band (～9.5 GHz) electron spin resonance spectroscopic measurements on the EcoRI–DNA–(Cu²⁺)₂ complex. Cu²⁺ binding results in two distinct components with different g_zz and A_zz values. X-band electron spin echo envelope modulation results indicate that both components arise from a Cu²⁺ coordinated to histidine. This observation is further confirmed by the hyperfine sub-level correlation results. W-band electron nuclear double resonance spectra provide evidence for equatorial coordination of water molecules to the Cu²⁺ ions.     

Theoretical investigations of the EPR parameters and local structure for Cu2+ in BeO

The electron paramagnetic resonance (EPR) parameters (the anisotropic g factors, the hyperfine structure parameters and the quadrupole coupling constant Q) and local structure for Cu²⁺ in BeO are theoretically investigated from the perturbation formulas of these parameters for a 3d⁹ ion under trigonally distorted tetrahedra. The ligand orbital and spin-orbit coupling contributions are included in the basis of the cluster approach, in view of the strong covalency of the [CuO₄]^6? cluster. From the calculations, the impurity Cu²⁺ is suggested not to occupy exactly the ideal Be²⁺ site but to suffer a slight inward displacement (≈0.024 Å) toward the ligand triangle along the C₃ axis. The theoretical EPR parameters show good agreement with the experimental data.     

The Interaction Between Levofloxacine Hydrochloride and DNA Mediated by Cu2+

Levofloxacin (LEV) is a fluoroquinolone antimicrobial agent. LEV also inhibits DNA synthesis and is bactericidal. The mechanisms of the interaction among LEV, DNA and Cu2+ are studied by fluorescence method. In the paper, the results show that LEV and Cu2+ can form binary complex, and also LEV and DNA can form complex mediated by Cu2+. The composition of the complex is determined. The affects to the reaction are also found.     

Luminescence in LiCaPO4

Phase pure LiCaPO₄ was prepared by following a specific procedure involving several annealing steps, not exceeding the temperature 800 °C at any stage. Luminescence of Cu⁺ and Eu²⁺ activators is studied. A single emission band is observed for both the activators in contrast to two bands reported in earlier literature. It is argued that in the earlier work the samples were contaminated by alpha Ca₃(PO₄)₂ phase, which could be responsible for these differences. Thermoluminescence of LiCaPO₄:Eu²⁺ was found to be four times more than the commercial phosphor LiF-TLD 100. Phase pure LiCaPO₄ shows interesting luminescence properties different than those reported in the literature and hence it should prove fruitful to probe this material in future.     

Theoretical explanation of electron paramagnetic resonance and optical parameters for Cu<Superscript>2+</Superscript> ion in LiNbO<Subscript>3</Subscript> crystal

The EPR parameters, anisotropic g-factors g _x , g _y and g _z for cu²⁺ ion and hyperfine structure constants A _x , A _y and A _z for Cu²⁺ in LiNbO₃ crystal are calculated by the method of diagonalizing the full Hamiltonian matrix. The crystal-field parameters contact with the crystal structure by the aid of the superposition model. The optical transition parameters are calculated using Zhao crystal-field model. The calculated results are in good agreement with the observed values. The results are discussed.