Radiative lifetimes of some excited levels in Eu II

Radiative lifetimes of the six levels 6p _3/2(7/2, 3/2)_{2, 3, 4, 5} and 6p _1/2(7/2, 1/2)_{3, 4} in Eu II are measured with a laser-ion beam technique using intracavity excitation and tandem pumping.     

Beam-foil lifetime measurements on energy levels of singly ionized Xenon

Radiative lifetimes were measured for levels of Xenon II by use of the beam-foil technique. Results are compared with other experimental and theoretical data. The coulomb approximation [1] was used to calculate lifetimes of the higher levels of Xenon II to facilitate an unambiguous assignment of the measured lifetime to a level.     

Radiative lifetimes for excited states in doubly ionized elements (21 ≤ Z ≤ 30) of astrophysical interest

Beam-foil technique has been applied to measurements of radiative lifetimes of 23 terms or levels, all belonging to the 3dⁿ4p (n = 0 to 9) configurations, in Sc(III), Ti(III), V(III), Cr(III), Mn(III), Fe(III), Ni(III) and Zn(III). The experimental lifetimes are in good agreement with lifetimes derived from oscillator-strength calculations, based upon the scaled Thomas-Fermi method, for ultraviolet lines in the spectra of the doubly ionized transition elements.     

Radiative lifetimes of some states of NeII

The radiative lifetimes of eight states of NeII, namely 3d, 3d′, 4s and 4s′, are measured. The delay-coincidence method with pulsed electron excitation is employed. A comparison with other results is also reported.     

Radiative lifetimes of some excited CoI states

The lifetimes of atomic CoI states have been determined using the delayed coincidence technique. A tunable dye laser pumped by a nitrogen laser was employed for the excitation of cobalt atoms in an atomic beam. The lifetimes were derived from the time dependent fluorescence intensity of the observed lines after the excitation. For the measurement of the lifetimes of thee ⁴ F _9/2,f ⁴ F ^9/2 andf ⁴ F _7/2 levels a two step excitation was applied. In case of overlapping measurement we find our results to be in good agreement with those reported by Becker [1].     

Radiative lifetimes of Zr III excited levels

We report on radiative lifetimes of 4d5p excited states of Zr III produced in a laser produced plasma. The ions were populated either in the ground state or in metastable states, and the number of ions is strongly dependent on the application of an external magnetic field, which is shown to be very important when using the time-resolved laser-induced fluorescence technique for lifetime measurements in highly charged ions. The experimental lifetime results fall in the region 1–2 ns with statistical uncertainties less than 7%. The experimental values were compared with multi-configuration Hartree-Fock calculations showing an agreement within 12–20%. The experimental values are systematically higher than the theoretical ones.     

Radiative lifetimes of excited W II levels

Radiative lifetimes of 19 selected W II levels with energies between 36 000 cm^-1 and 55 000 cm^-1 have been measured with the time-resolved laser-induced fluorescence technique. The ions are generated in a hollow cathode discharge and stored in a linear Paul trap. Selected states are populated with tunable dye laser pulses and the subsequent fluorescence is measured by means of a 5 Gigasample transient digitizer and a fast photodetector with a risetime of 700 ps. By taking into account both the temporal profile of the laser pulses and the separately measured response function of the system, the lifetime can be determined from the full decay curve. A refined evaluation procedure, taking into account saturation effects in the signals, reduces the uncertainty in our data to around 1%. Received: 30 July 1998 / Revised: 18 August 1998     

Radiative lifetimes of superradiant populated Ba Rydberg levels

Radiative lifetimes of 6s7f¹F₃, as8f¹F₃, and 6s9d¹D₂ Ba Rydberg levels were measured in an atomic beam by time resolved recording of the exponential decay of the fluorescence. The excitation was performed by use of two pulsed dye lasers and a superradiant emission or a superradiant cascade controlled by a cavity.     

Radiative lifetimes of some excited states of neutral xenon

The radiative lifetimes of ten levels belonging to the nf (n=4-7) and three levels belonging to the ns (n=8,9) configuration of XeI have been measured using the high frequency deflection technique together with a delayed coincidence single-photon counting arrangement. Lifetimes of some of the levels have been measured for the first time. The results have been compared with other experimental and theoretical values.     

Radiative lifetimes of highly excited odd-parity levels of neutral lanthanum

New radiative lifetimes of 24 high-lying odd-parity levels of neutral lanthanum are reported using time-resolved laser-induced fluorescence (TR-LIF) spectroscopy. The investigated levels ranging from 34 213 to 40 910 cm^-1 were excited from the ground or metastable states using one-photon excitation. La atoms are produced by laser ablation on a solid La sample. The lifetimes were evaluated from transient LIF signals detected with a fast detection system. The obtained lifetime results, generally with uncertainties less than  ±7%, are in the range from 15.7 to 121 ns.     

Radiative lifetimes of the levels in the Ba III spectrum

The radiative lifetimes of the 5p ⁵ (6s+5d), 5p ⁵ (6p+4f), and 5p ⁵5f levels in the spectrum of the Ba III ion are calculated. The wave functions of the intermediate coupling are found from the experimental energy levels by the method of least squares. The radial transition integrals are calculated by the Hartree-Fock method.     

Experimental lifetimes of some levels of KrI

Lifetime of nine levels belonging to the and configuration of neutral krypton have been measured by high-frequency deflection technique with a delayed coincidence single photon counting arrangement. The results have been compared with other experimental and theoretical values. The lifetimes of the 9s[3/2]₁ and 7p[1/2]₀ levels have been measured for the first time.     

Radiative corrections to positronium energy levels

A systematic perturbation theory for the computation of positronium energy levels is presented. The proposed method is based on the Bethe-Salpeter equation and a zeroth-order kernel for which exact solutions are known explicitly. The cancellation of ultraviolet divergences arising in the perturbation series is discussed, and new contributions to the ground-state hyperfine splitting of positronium are evaluated up to order α⁶.     

Radiative lifetimes of optical levels of neutral erbium,gadolinium and neodymium

Lifetimes of 47 atomic levels (energy range between 16,000 and 27,000 cm^?1) of ErI, GdI and NdI have been determined using the selective pulsed laser excitation of the atoms in an atomic beam and applying the delay coincidence method for registration.     

Beam-foil lifetimes of highly ionized silicon

Electronically excited states of Si ions are created by passing a 20 MeV Si⁵⁺ beam through a thin carbon foil. The EUV-radiation (λ=13–61 nm) emitted by the beam is analyzed using a grazing-incidence spectrometer. From the decay curves, lifetimes of 24 low lying levels in Si VIII to Si XII and of the 4f and 5g levels of Si XI and Si XII are derived. Cascades from doubly excited states turn out to be an important contribution to the radiation observed. The lifetime values of this work are compared to theoretical data mainly of Wiese, Sinanoλu and Dankwort/Trefftz. Most experimental values agree with at least one of the theoretical values. The decay time 560 ps of the 2s2p ^{3 3} D ₃ ⁰ state of Si IX is clearly longer than the theoretical prediction (highest value 455 ps by Sinanoglu).     

单电离态Kr原子的能级寿命的研究

在 12 0keV的能量下 ,用束 -箔方法研究了跃迁强谱线的单电离态Kr原子激发态能级5p4 D07/2 ,5p4 D05/2 的寿命。并与理论和其它实验结果做了比较和讨论。     

Radiative lifetimes of some excited states of Hg+ and Hg2+

A delayed-coincidence method with pulsed electron excitation was used to measure the radiative lifetimes of some 5d⁹6snl states of Hg⁺. Radiative lifetimes of five long lived 5d⁸6s² states of Hg²⁺ and some Hg²⁺ spectral line transition probabilities are also reported. The data are obtained for the first time.     

Radiative transitions from singly ionized oxygen

 Fully relativistic calculations have been performed on the states of configurations of singly ionized oxygen. The calculations have been carried out using multi-configuration Dirac-Fock wavefunctions with the inclusion of Breit interaction and quantum electrodynamic contributions. A substantial amount of correlation has also been included in our calculations. The numerical results for more than 150 electric dipole lines in the spectrum of O⁺ are compared with other theoretical and experimental values.     

Breit-Pauli energy levels and radiative lifetimes in neutral chlorine

Breit-Pauli Energy levels, oscillator strengths and transition probabilities for all the transitions in Cl I between the fine structure levels of 3s² 3p⁵, 3s² 3p⁴3d, 3s² 3p⁴4s and 3s²3p⁴4p states are calculated using extensive configuration interaction (CI) wave functions. We have also determined the lifetimes of 3s² 3p⁴3d, 3s² 3p⁴4s and 3s² 3p⁴4p levels. The relativistic effects are included through Breit-Pauli approximation via spin-orbit, Darwin and mass correction terms. Prior to the calculations of the oscillator strengths and transition probabilities, we fine-tune the CI coefficient using experimental energies. Our results are compared with experimental and other available theoretical data. The calculated energy levels are in close agreement with most of the NIST compiled data. We predict new lifetime data for several levels where no other theoretical and/or experimental results are available, which will form the basis for the future experimental work. Electronic supplementary material Online Material     

Radiative lifetimes and transition moments in MgO

An experimental and theoretical study of several transitions in the MgO molecule is reported. The radiative lifetime of the MgO B¹Σ⁺v'=0 level is measured to be 32.7±1.7 nsec, while that of the electronic state(s) excited by 372 nm radiation (d³Δ and/or f³Π) is 11.8±0.5 nsec. The B-X and A-X transition moments are calculated using state averaged multiconfiguration self-consistent field and configuration interaction methods. With an estimate of the B-A transition moment derived from an earlier calculation, the radiative lifetime of the B¹Σ⁺v'=0 level is computed to be 24 nsec. A value of 0.23 msec is calculated for the lifetime of A¹Πv'=0.