Lifetimes and oscillator strengths of neutral vanadium

Oscillator strengths of 105 V(I) lines in the spectral range 2800–6000 Å were obtained by lifetime, emission, and hook measurements. Relative sets of ?-values were determined by combining emission measurements on a hollow cathode with hook measurements in a high temperature furnace, whereby no assumption concerning the plasma state is used and no temperature determination is required. The determination of the radiative lifetimes was performed by selective laser excitation of an atomic beam of vanadium and time-resolved observation of the reemitted fluorescence after the pulse. The absolute ?-values have an uncertainty of 12% on average. Both for the lifetimes and the ?-values a comparison with literature data is performed.     

Determination of oscillator strengths with the phase-matching condition

A new method for determining transition probabilities of atomic and molecular system has been demonstrated. It is based on a measurement of the refractive index using the phase matching condition in frequency mixing or harmonic generation experiments. For the oscillator strength of the first Rb-resonance line a value of 1.07 ± 0.02 has been obtained.     

Relativistic and nonrelativistic oscillator strengths in the Na isoelectronic sequence

We report the general trend of the nonrelativistic Hartree-Fock relativistic Hartree-Fock, nonrelativistic configuration-interaction, and relativistic configuration-interaction length form of the oscillator strengths for the resonance excitation 1s ²2s ²2p⁶3s ² S _J ^e 1s ²2s ²2p ⁵3s ^{2 2} P _J ^o . transition, which leads to autoionization (Auger transition), in Na, Mg¹⁺, Al²⁺, Si³⁺, P⁴⁺, S⁵⁺, Cl⁶⁺, Ar⁷⁺, K⁸⁺, Ca⁹⁺, Sc¹⁰⁺, Ti¹¹⁺, Fe¹⁵⁺, Cu¹⁸⁺, Zn¹⁹⁺, Br²⁴⁺, and Kr²⁵⁺ ions of the sodium isoelectronic sequence.     

Theoretical and experimental determinations of cesium oscillator strengths

The oscillator strengths of the cesium atom have been calculated theoretically using a semi-empirical construction of the effective potential acting on the valence electron. The results are compared with those deduced from an experimental determination in a quiescent cesium plasma.     

Broadening and oscillator strengths of Cs quadrupole lines

The oscillator strengths of the first 14 quadrupole lines of $\text{Cs}\text{(6}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{→5?11}{}^2\text{D}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext><mtext>,</mtext><mtext>3</mtext><mtext>2</mtext>}}\text{)}$ were measured in absorption using a high resolution spectrometer. In addition to this, the broadening of the$\text{6}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{→5}{}^2\text{D}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ and $\text{6}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{→5}{}^2\text{D}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ lines was investigated. Taking into account not only the impact region of the lines but also the quasi-static wings, the integrated absorption of the lines increases overproportionally to the practicle density. It was established that the electron transitions which form the quasi-static wings of the lines(molecular electron transitions) have higher transition probabilities than the corresponding impact broadened lines. A rough estimate of the molecular oscillator strengths is given.     

Optical oscillator strengths for the sulphur isoelectric sequence

An analytic atomic independent-particle-model potential, adjusted to experimental energy levels, is used to calculate optical oscillator strengths for S, Cl⁺¹, Ar⁺², K⁺³, Ca⁺⁴ and Sc⁺⁵.     

Theoretical ionization energies and oscillator strengths for carbon

Frozen core Hartree-Fock wave functions have been calculated for 98 excited s-, p- and d-levels of C(I), and employed to calculate electric dipole oscillator strengths for all allowed transitions between these levels. The energy levels generally agree with observations to within 1.3% and the length and velocity forms of the calculated л-values agree well except for very weak transitions.     

Theoretical term energies and oscillator strengths for carbon

Thomas-Fermi-Hartree-Fock wave functions have been calculated for nl-terms of carbon C(I) (n≤10 and l≤3) and employed to calculate electric dipole oscillator strengths for all allowed transitions between these terms. The dipole length and velocity form of the calculated f-values agree well with the available measurements.     

Resonance transition energies and oscillator strengths in lutetium and lawrencium

The transition energies and oscillator strengths for nd (2)D(3/2)-(n+1)p (2)P(o)(1/2,3/2) transitions in Lu ( n = 5, Z = 71) and Lr ( n = 6, Z = 103) were calculated with the multiconfiguration Dirac-Hartree-Fock method. The present study confirmed that the ground state of atomic Lr is [Rn]5f(14)7s(2)7p (2)P(o)(1/2). The calculation for Lr required wave function expansions of more than 330 000 configuration states. In Lu, the transition energies, with Breit and QED corrections included, agree with experiment to within 126 cm(-1). In lighter elements, core correlation is usually neglected but was found to be of extreme importance for these heavy elements, affecting the oscillator strengths by a factor of 3 and 2 in Lu and Lr, respectively.     

Theoretical oscillator strengths for the NI and OI resonance transitions

We report results from the first many-body calculations of the important oscillator strengths of the resonance lines NI $\text{1s}{}^2\text{2s}{}^2\text{2p}{}^3{}^4\text{S°?is}{}^2\text{2s}{}^2\text{2p}{}^2\text{3s}{}^4\text{P(λ=1200}\text{A}\text{?}\text{), 1s}{}^2\text{p}{}^2\text{3d}{}^4\text{P(λ=953}\text{A}\text{?}\text{)}$ and OI $\text{1s}{}^2\text{2s}{}^2\text{2s}{}^2\text{2p}{}^4{}^3\text{P ?1s}{}^2\text{2s}{}^2\text{2p}{}^3\text{3s}{}^3\text{S°(λ = 1304}\text{A}\text{?}\text{)}$. Our values are: $\text{?(1200)=0·271; ?(1304)=0·047; ?(953)= ·082}$. The first two are in excellent agreement with recent lifetime and absorption measurements and thus the existing discrepancy between theory and experiment is resolved. The third number constitutes the only available result for this transition.     

Determination of oscillator strengths for UI and UII lines

The emission spectrum of a uranium plasma obtained in a hollow cathode was studied to determine plasma characteristics of uranium atoms such as temperature plasma-excitation, temperatures of neutral species, and oscillator strengths (gf values) of more than 370 lines of the U_I and U_II spectra.     

Weighted oscillator strengths and lifetimes for the S XIV spectrum

The weighted oscillator strengths gf and the lifetimes for S XIV presented in this work have been calculated in a multiconfigurational Hartree–Fock relativistic approach. In this calculation, the electrostatic parameters were optimized by a least-squares procedure in order to improve the adjustment to experimental energy levels. This method produces gf values that are in better agreement with observed line intensities and lifetime values closer to the experimentally determined ones. In this work we presented all the experimentally known electric dipole S XIV spectral lines. Published in Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 473–476, 2009.     

Weighted oscillator strengths and lifetimes for the Si II spectrum

The weighted oscillator strengths (gf) and the lifetimes for Si II presented in this work were carried out in a multiconfiguration Hartree–Fock relativistic (HFR) approach. In this calculation, the electrostatic parameters were optimized by a least-squares procedure, in order to improve the adjustment to experimental energy levels. This method produces gf-values that are in better agreement with intensity observations and lifetime values that are closer to the experimental ones. In this work we presented all the experimentally known electric dipole Si II spectral lines.     

Photoionization cross sections and oscillator strengths of neutral cesium

The absolute photoionization cross sections from the 6p ²P_1/2 excited state of cesium at threshold and above the threshold region have been measured using the saturation absorption technique. The photoionization cross section at the ionization threshold is determined as 22.6±3.6 Mb, whereas in the region above threshold its value ranges from 22 to 20 Mb for photoelectron energies up to 0.1 eV. A comparison of the photoionization cross sections with earlier reported theoretical and experimental data have been presented and are in good agreement within the uncertainty. In addition, the oscillator strengths of the 6p ²P_1/2→n d ²D_3/2 (21≤n≤60) Rydberg transitions of cesium have been calibrated using the threshold value of the photoionization cross section. A complete picture of the oscillator strengths from the present work and previously reported data from n=5–60 is presented.     

Energy levels, oscillator strengths and lifetimes in Ar V

We have calculated the excitation energies, oscillator strengths and transition probabilities for electric-dipole-allowed and intercombination transitions among the 46 LS levels belonging to the configurations 3s ²3p ², 3s3p ³, 3s ²3p3d, 3p ⁴, 3s ²3p4s, 3s ²3p4p, 3s3p ²(² S)4s, 3s3p ²(² P)4s, 3s3p ²(⁴ P)4s, 3s3p ²(² D)4s, 3s ²3p4d and 3s ²3p4f of Si-like Argon. These states are represented by extensive Configuration-Interaction (CI) wavefunctions obtained using the CIV3 computer code of Hibbert. From our transition probabilities we have also calculated the radiative lifetimes of singlet and triplet states of Ar V. Our results are compared with other available theoretical calculations and experimental data. To assess the importance of relativistic effects on our calculated values, we have also carried out calculations in the intermediate-coupling scheme using the Breit-Pauli Hamiltonian. Small adjustments to the diagonal elements of the Hamiltonian matrices have been made so that the energy splittings are as close as possible to the experimentally compiled energy values of the National Institute for standards and Technology (NIST). The energy splitting of 85 fine-structure levels, the oscillator strengths and transition probabilities for electric-dipole-allowed and intercombination transitions and the lifetimes of some fine-structure levels are presented and compared with available experimental and other theoretical values. In this calculation, we also predict new data for several fine-structure levels where no other theoretical and experimental results are available.     

类Na离子振子强度的相对论效应

 采用相对论和非相对论原子自洽场方法,计算了类Na离子（原子序数为11~92）的3s-np,3p-ns和3p-nd跃迁过程的激发能和光学振子强度;通过比较相对论与非相对论的结果,研究了M壳层电子的相对论效应随原子序数的变化规律。结果表明：对n=3的跃迁过程,相对论效应主要是影响激发能,对线强度(或跃迁矩阵元)的影响不重要;对于n>3的跃迁过程,相对论效应同时影响线强度和激发能,通常对线强度的影响更大。这些结果对惯性约束聚变和X射线激光研究中需要的不透明度参数计算有重要的参考意义。     

Measurement of the oscillator strengths of principal-series lines of cesium

Extensive high resolution absorption measurements of the oscillator strengths of principal-series lines of cesium were carried out, up to the principal quantum number 18, in order to investigate the effect of spin-orbit interaction on fine-structure doublets. The oscillator strengths of the stronger components exhibit a different dependence on the effective principal quantum number from that marking the weaker components, but no maximum in doublet oscillator-strength ratio was found.     

类Na离子振子强度的相对论效应

采用相对论和非相对论原子自洽场方法,计算了类Na离子（原子序数为11~92）的3s-np,3p-ns和3p-nd跃迁过程的激发能和光学振子强度;通过比较相对论与非相对论的结果,研究了M壳层电子的相对论效应随原子序数的变化规律。结果表明：对n=3的跃迁过程,相对论效应主要是影响激发能,对线强度(或跃迁矩阵元)的影响不重要;对于n>3的跃迁过程,相对论效应同时影响线强度和激发能,通常对线强度的影响更大。这些结果对惯性约束聚变和X射线激光研究中需要的不透明度参数计算有重要的参考意义。