Oscillator strengths for the 2s2, 2p2, 2s3s(1S)-2s2p(1P) transitions of B(II)

Accurate configuration interaction wavefunctions for the 2s²(¹S), 2p²(¹S), 2s3s(¹S) and 2s2p (¹P) states of B(II) are calculated in a single optimized orbital basis of 7s, 6p and 4d Slater-type orbitals. 95, 84, 57 and 90% of the correlation energies, respectively, are realized by these wavefunctions. Oscillator strengths for the three ¹S-¹P transitions are calculated from these and from less accurate wavefunctions in the same orbital basis. The length values obtained from our most accurate wavefunctions, in order of increasing ¹S energy, are 0.9885, 0.202 and 0.007. The degree of accuracy of these oscillator strengths is estimated by noting the convergence to final values as increasing percentages of correlation energies are included in the wavefunctions together with the increasing agreement between length and velocity formulas. The exact theoretical oscillator strength for the resonant line is projected to be 0.985 with an error almost certainly not greater than ±0.015. The theoretical oscillator strengths for the other lines are considered to be 0.21±0.02 and less than 0.007, respectively.     

Na 32P-32D line broadening by Ne,Ar, and Xe

The normalized emission intensity in the wings of the optically thin Na 3²P-3²D lines broadened by Ne, Ar, and Xe has been measured in emission from a high-pressure discharge. A blended satellite occurs about 80 cm^-1 into the Na-Xe red wing and a progression of increasing red wing intensity from Ne to Ar to Xe is observed. Xe densities of 2.5 and 9.1 × 10¹⁹ cm^-3 were used, and the pressure dependence of the NaXe line shape indicates that multiple perturber interactions are important in the far wing at the higher noble gas densities.     

Ion dynamic correction to the profile of the forbidden 23P-43F transition of He(I)

Dynamic corrections due to ion (and emitter) motion have been calculated for the profile of the forbidden 2³P-4³F transition of He(I) for ion density n_i = 10¹⁵ cm^-3 and plasma temperature T = 10⁴ K. The calculation is based on a “corrected binary collision treatment”; comparison is made with a similar approach published previously by Barnard, Cooper, and Smith.     

Oscillator strengths for 2 ^2P-n ^2D transitions of lithium-like systems with Z=11 to 20

The dipole-length, velocity and acceleration absorption oscillator strengths for the 1s^22p－1s^2nd(3≤n≤9) transitions of the lithium-like systems with Z=11 to 20 are calculated using the energies and the multiconfiguration interaction wavefunctions obtained from a full core plus correlation method. The agreement between the f-values calculated from the length, velocity and acceleration formulae is excellent. Our results agree closely with the experimental data available in the literature. Combining these discrete oscillator strengths with the single-channel quantum defect theory, the discrete oscillator strengths for the transitions from 1s^22p state to highly excited states (n≥10) and the oscillator strength densities corresponding to the bound-free transitions are obtained.     

Oscillator strengths for 22S--n2P transitions of the lithium isoelectronic sequence from Z = 11 to 20

The dipole-length, dipole-velocity and dipole-acceleration absorption oscillator strengths for the 1s22s-1s2np (3≤n≤9) transitions of lithium-like systems from Z=11 to 20 are calculated by using the energies and the multiconfiguration interaction wave functions obtained from a full core plus correlation method, in which relativistic and mass-polarization effects on the energy, as the first-order perturbation corrections, are included. The results of three forms are in good agreement with each other, and closely agree with the experimental data available in the literature. Based on the quantum defects obtained with quantum defect theory (QDT), the discrete oscillator strengths for the transitions from the ground state to highly excited states 1s2np (n≥10) and oscillator strength densities corresponding to the bound-free transitions are obtained for these ions.     

Oscillator strengths and transition probabilities of the Be(I) isoelectronic sequence for 2p2-2s2p and 2s2p-2s2 transitions

Oscillator strengths and transition probabilities are obtained from an intermediate coupling scheme. The initial basis of the eigenstates is formed inLS-coupling. To obtain the resulting energy matrix,Z^-1 perturbation theory is applied. The values of oscillator strengths and transition probabilities for 1s²2p²?1s²2s2p and 1s²2s2p?1s²2s² transitions are calculated and the comparison is made with some recent results. The nuclear charges (Z) involved varied fromZ=4(Be(I)) toZ=35(Br(XXXII)).     

Oscillator strengths for 2 transitions of the lithium isoelectronic sequence

The nonrelativistic dipole-length, -velocity and -acceleration absorption oscillator strengths for the 1s²2s-1s²np (3 ￡ n ￡ 9)(3\leq n\leq 9) transitions of the lithium isoelectronic sequence up to Z=10 are calculated by using the energies and the multiconfiguration interaction wave functions obtained from a full core plus correlation (FCPC) method. In most cases, the agreement between the f-values from the length and velocity formulae is up to forth or fifth digit. Combining these discrete oscillator strengths with the single channel quantum defect theory (QDT), the discrete oscillator strengths for the transitions from the 1s^22s state to highly excited levels (n 3 10n \geq 10) and the oscillator strength densities corresponding to the bound-free transitions are obtained.     

Model-potential oscillator strengths for 4fn6s2–4fn6s6p transitions in Sm(I), Eu(I), Dy(I), Er(I) and Yb(I)

The 4fⁿ6s²?4fⁿ6s6p transitions are studied for neutral samarium, europium, dysprosium, erbium, and ytterbium. Four different couplings between the valence electrons and the 4fⁿ shell are considered, three are based on the LS and one on the J_IJ_II scheme. The radial integrals are computed with the model-potential method, which includes both exchange and core polarization. The results are compared with those obtained by employing the Coulomb approximation and the ab initio Hartree + Exchange (HX) approach, as well as with available experimental data. The core-polarization influence on oscillator strengths for these transitions is also investigated.     

Alpha-particle strengths from the 16O(6Li,d)20Ne reaction

The ¹⁶O(⁶Li, d)²⁰Ne reaction has been studied at bombarding energies of 20, 32 and 38 MeV. The α-particle spectroscopic strengths have been extracted for levels up to 12.15 MeV in excitation. Nondirect processes appear to contribute significantly to all levels at 20 MeV and to high spin levels (6⁺ and 8⁺) at 32 MeV. Strengths extracted for members of the ground state band assuming (sd)⁴ transfer are unequal at both 32 and 38 MeV, in marked contrast to theoretical predictions. To explain this, particle-hole correlations in ¹⁶O(g.s.), inelastic channel coupling in the reaction and perhaps other effects as well, have to be considered. Strengths extracted for members of excited bands and α-decay reduced widths compare poorly with each other and with simple SU(3) predictions.     

铜原子单激发态3d104p 2P1/2的光电离(英文)

铜原子能级结构的理论计算具有非常大的挑战性。本文基于多组态Dirac-Hartree-Fock（MCDHF）方法和相对论组态相互作用（RCI）方法,通过三个大规模的关联模型计算了单激发态3d104p 2P_1/2、双激发态3d94s（3D）5s4D_3/2,1/2,3d94s（3D）5s 2D_3/2,3d94s（1D）5s 2D_3/2以及离子态3d10 1S₀能级和波函数。结果表明,铜原子能级结构对有限组态空间的选择极其敏感,双激发态3d94s（3D）5s 4D_3/2,1/2,3d94s（3D）5s 2D_3/2,3d94s（1D）5s 2D_3/2和离子态3d10 1S₀与单激发态之间的能量差相对于已有实验结果均存在大约-0.4 eV的偏差,而计算得到的共振电子能量与实验结果符合得较好。此外,根据辐射跃迁矩阵元和非辐射跃迁矩阵元计算了双激发态的Fano参数q,并基于Fano理论得到了铜单激发态3d104p 2P_1/2的总光电离截面,该理论考虑了直接光电离与光激发自电离之间的干涉效应,即共振3d94s（3D）5s 4D_3/2,1/2、3d94s（3D）5s 2D_3/2和3d94s（1D）5s 2D_3/2具有明显的非对称的Fano轮廓,表明光电离过程与光激发自电离过程之间的干涉对双激发态共振附近的光电离截面轮廓有着极其重要的影响。     

Gamma-ray transitions from the lowest f = 2 states of 24Na and 28Al

Using a DWBA code which exactly includes finite-range and recoil effects, calculations are shown for ¹²C(¹⁶O, ¹²O)¹⁶O, ⁴⁰Ca(¹⁶O, ¹²C)⁴⁴Ti and ⁴⁰Ca(⁶Li, d)⁴⁴Ti which seem to be in quantitative agreement with the assumption that these reactions proceed via the simple one-step transfer of an α-particle.     

Oscillator strengths in certain air molecule systems—I. The O2 Schumann-Runge system

The extended-basis molecular wave functions of Cade are utilized for the computation of the electronic transition moment in the AEVO approximation for the Schumann-Runge system. The calculation is carried out for both the dipole length and dipole velocity forms of the operator. The matrix elements are, to a good approximation, linear functions of internuclear separation in both forms. The electronic oscillator strength thus computed differs from the most recent experimental value by a factor of three. The introduction of the dipole centroid yields results differing by about 50 per cent from observed.     

The 6Li(α, 2α)2H reaction at 700 MeV and the α-d momentum distribution

The results of an experimental study of the reaction ⁶Li(α, 2α)²H at 700 MeV are given. A comparison with the data from seven other reactions pertaining to the α⁺d cluster structure of ⁶Li is presented. The amplitude for the virtual transition ⁶Li→α+d obtained three of these experiments and the present one are comparable. The internal momentum distributions extracted with the plane-wave impulse approximation in four of the experiments are compatible with a pole form, the width parameter being given by the α-separation energy in ⁶Li. The remarkable consistency among these results is seen as evidence for the validity of the simple models used for both the reaction mechanism (PWIA) and to describe the α d-vertex (pole approximation) in ⁶Li.     

The identification of two entrance channels in the reaction of metastable helium He(23S,21S) with SO2

The energy spectrum of electrons emitted in the reaction of He(2³S) and He(2¹S) with SO₂ indicates that in addition to the covalent entrance channel a strongly attractive ionic channel plays a role. We find upper limits for the well depth of the potential curve that corresponds to the latter channel of D_e ? 3.5 eV and D_e ? 4.3 eV for He(2³S) and He(2¹S) as the reaction partner, respectively. The partitioning between the two entrance channels can be understood by assuming the coupling matrix between both channels to depend strongly on the orientation of the SO₂ molecule with respect to the incident metastable He*.     

The spin(6) scheme and electromagnetic transitions in 191Ir and 193Ir

The Coulomb excitation of natural Ir and Pt targets has been measured with protons and α-particles of energies between 5.0 and 6.0 MeV. Accurate γ-ray angular distributions were taken to determine the relative yields of observed γ-rays. Using ¹⁹⁴Pt as standard the reduced electric quadrupole transition probabilities to the ground states from Coulomb excited levels in the Ir and Pt isotopes were determined. Other B(E2) and B(M1) values were determined from the decay schemes obtained and from mixing ratios deduced from γ-ray angular distributions or from previously measured internal conversion coefficients. The detailed sets are compared with calcula- tions based on the Spin(6) scheme, which predicts several symmetries in ¹⁹¹Ir and ¹⁹³Ir. The possible existence of wider supersymmetry multiplets in this region of nuclei is examined on the basis of comparison of electromagnetic properties of Ir nuclei with those of Pt and Os isotopes.     

A study of the 84Kr(α, 2nγ)86Sr reaction

Decay properties of levels of ⁸⁶Sr populated by the 28 MeV ⁸⁴Kr(α, 2nγ) reaction have been studied by in-beam γ-ray spectroscopy. The observation of several new levels with $\text{J ≧ 6}$ allows a detailed comparison of the 2p-2n structures of ⁸⁶Sr with those of neighboring N = 48 nuclei. The results are discussed in terms of the weak-coupling model.     

Fine structure in the absorption edge spectrum of NbS2Y2 (Y = Cl,Br, I)

High resolution absorption spectra of single crystals of NbS₂Y₂ (Y = Cl, Br, I), obtained at temperatures between 4.2 and 300 K revealed extensive fine structure in the absorption edge. This structure has been analysed and interpreted in terms of allowed indirect interband transitions, involving phonons corresponding to SS and NbS vibrations, followed by forbidden and by allowed direct transitions. From the shape of the absorption curve associated with the phonon branches of the indirect transitions a binding energy of 23 cm^? for indirect excitons is obtained. A binding energy of 28 cm^? for direct excitons is deduced from the exciton lines observed at the long-wavelength side of the direct transitions. A detailed interpretation of the optical transitions is given in terms of a molecular orbital diagram for the Nb₂S₄ clusters, present in these crystals.     

The reaction 26Mg(d, τ)25Na and the structure of 25Na

The nuclear structure of the nucleus ²⁵Na has been studied with the (d, τ) proton pick-up reaction on ²⁶Mg at a bombarding energy of 29 MeV with an energy resolution of 25 to 30 keV FWHM. Excited states in ²⁵Na have been measured up to excitation energies of 8 MeV. The experimental angular distributions show good agreement with the predictions from the standard distorted-wave Born-approximation theory (code DWUCK; non-local and finite range). However, the agreement is improved considerably if the procedure of Kunz, Rost and Johnson is applied which accounts approximately for strong couplings to inelastic channels in the initial and final (strongly deformed) nuclei. The influence of this treatment on the evaluation of spectroscopic factors has been investigated and was found to be particularly pronounced for l = 0 transitions. The measured spectroscopic factors are compared to those from other experimental work and from shell-model and Nilsson-model calculations.     

Oscillator strengths of ultraviolet V(II) lines from measurements in a vanadium-helium plasma

A V-He plasma has been produced in a well-stabilized arc. Oscillator strengths for 66 V(II) lines in the range 2342–2617 Å have been determined. Comparisons with theoretical values show large discrepancies for about 25% of the lines, possibly due to errors in calculations and in term classifications.