Radiative lifetimes for the 4p excited states of phosphorus and the oscillator strengths of solar lines
2
Citation
0
Reference
19
Related Paper
Abstract:
Radiativelifetimesforthelevelsofthe3s 2 3p 2 4pcon- figuration in neutral phosphorus have been determined experi- mentally for the first time and also theoretically. Experiments were performed by using two-photon UV laser excitation and subsequent fluorescence detection in a laser-produced plasma. In relativistic Hartree-Fock calculations, the Cowan code ex- tended to 42 configurations was used. Finally, the lifetimes for all the 13 excited states in the 4p configuration were calculated and for 6 of them the values were measured experimentally. Theoretical branching ratios were combined with experimental lifetimes, to deduce oscillator strengths and these were used for the evaluation of the phosphorus abundance in the sun. A value of 5.49 (0.04) was obtained in the usual logarithmic scale.Cite
New radiative lifetimes have been measured for the 5s 3Po0, 1, 2 and 5s 1Po1 levels of Gei using a laser-produced plasma subject to selective laser excitation. A diffraction grating based emission spectrometer of moderately high resolution has been used to remeasure the branching ratios of the 4p—5s depopulating transitions. The oscillator strengths of astrophysical interest, which have been derived from these new data, are compared with theoretical values calculated within a pseudo-relativistic Hartree—Fock approach. The new set of f-values has been compared with the few results available in the literature, which are generally characterized by a large scatter and a low accuracy. The solar photospheric abundance of germanium deduced from the new atomic data of the present work is AGe = 3.58 ± 0.05, on the usual logarithmic scale, in agreement with the meteoritic value.
Collisional excitation
Branching fraction
Cite
Citations (15)
Abstract Radiative lifetimes of 62 odd-parity levels of Ir i in the energy range between 32513.43 and 58625.10 cm −1 were measured using the time-resolved laser-induced fluorescence technique. The lifetime values obtained are in the range from 3.2 to 345 ns. To our best knowledge, 59 results are reported for the first time. These are compared to computed data deduced from a pseudo-relativistic Hartree–Fock model including core-polarization contributions. From the combination of the experimental lifetime measurements and branching fraction calculations, a new set of transition probabilities and oscillator strengths is derived for 134 Ir i spectral lines of astrophysical interest in the wavelength region from 205 to 418 nm.
Branching fraction
Parity (physics)
Branching (polymer chemistry)
Cite
Citations (2)
Radiative lifetimes of 17 excited states in Zr I, in the energy interval 29000 - 40974 cm-1, have been investigated using the Time-Resolved Laser-Induced Fluorescence (TR-LIF) method. The levels belong to the 4d25s5p, 4d35p and 4d5s25p electronic configurations were excited in a single - step process from levels belonging to the ground 4p25s2 a 3F or to low-lying 4p25s2 a 3P, a 5F terms. For 14 levels, the lifetimes have been measured for the first time. Experimental results are compared with theoretical calculations performed with a multiconfigurational relativistic Hartree-Fock method including core polarization effects.
Cite
Citations (0)
Radiative lifetimes of 17 excited levels in Zr i, in the energy interval 29 000–40 974 cm−1, have been investigated using the time-resolved laser-induced fluorescence method. The levels belong to the 4d25s5p, 4d35p and 4d5s25p electronic configurations and were excited in a single-step process from either the ground term, 4d25s2 a 3F, or from the low-lying 4d25s2 a 3P and a 5F terms. For three levels, we confirm previous measurements while for 14 of the levels the lifetimes have been measured for the first time. The experimental results are compared to theoretical calculations performed with a multiconfiguration relativistic Hartree–Fock method including core-polarization effects. Theoretical transition probabilities of astrophysical interest, scaled by the experimental lifetimes, for the depopulating channels of the investigated levels are also presented.
Cite
Citations (9)
The lifetimes of 17 even-parity levels (3d5s, 3d4d, 3d6s and 4p 2 ) in the region 57 743-77 837 cm -1 of singly ionized scandium (Sc II) were measured by two-step timeresolved laser induced fluorescence spectroscopy.Oscillator strengths of 57 lines from these highly excited upper levels were derived using a hollow cathode discharge lamp and a Fourier transform spectrometer.In addition, Hartree-Fock calculations where both the main relativistic and core-polarization effects were taken into account were carried out for both low-and high-excitation levels.There is a good agreement for most of the lines between our calculated branching fractions and the measurements of Lawler & Dakin in the region 9000-45 000 cm -1 for low excitation levels and with our measurements for high excitation levels in the region 23 500-63 100 cm -1 .This, in turn, allowed us to combine the calculated branching fractions with the available experimental lifetimes to determine semi-empirical oscillator strengths for a set of 380 E1 transitions in Sc II.These oscillator strengths include the weak lines that were used previously to derive the solar abundance of scandium.The solar abundance of scandium is now estimated to log = 3.04 ± 0.13 using these semi-empirical oscillator strengths to shift the values determined by Scott et al.The new estimated abundance value is in agreement with the meteoritic value (log met = 3.05 ± 0.02) of Lodders, Palme & Gail.
Scandium
Cite
Citations (14)
This work reports new experimental radiative lifetimes and calculated oscillator strengths for transitions from 3d8 4d levels of astrophysical interest in singly ionized nickel. Radiative lifetimes of seven high-lying levels of even parity in Ni II (98400 -100600 cm-1) have been measured using the time-resolved laser-induced fluorescence method. Two-step photon excitation of ions produced by laser ablation has been utilized to populate the levels. Theoretical calculations of the radiative lifetimes of the measured levels and transition probabilities from these levels are reported. The calculations have been performed using a pseudo-relativistic Hartree-Fock method, taking into account core polarization effects. A new set of transition probabilities and oscillator strengths has been deduced for 477 Ni II transitions of astrophysical interest in the spectral range 194 - 520 nm depopulating even parity 3d8 4d levels. The new calculated gf-values are, on the average, about 20 % higher than a previous calculation by Kurucz (http://kurucz.harvard.edu) and yield lifetimes within 5 % of the experimental values.
Parity (physics)
Oscillator strength
Cite
Citations (4)
Radiative lifetimes of 17 excited levels of Nb i, in the energy range 27 400–47 700 cm−1 (5p y 6D°9/2, 5p x 6D°7/2, 5p w 4G°7/2,9/2,11/2, 5s5p v 4D°1/2,3/2,5/2,7/2, 5s6p n 4D°1/2,3/2,5/2,7/2, 5s6p o 4F°3/2,5/2,7/2,9/2), have been measured. For 15 of these levels, the lifetimes are obtained for the first time. The lifetimes were measured using the time-resolved laser-induced fluorescence technique and the experiments are complemented by a theoretical investigation using a relativistic Hartree–Fock method including core polarization. By combining the experimental lifetimes and the calculated branching fractions, we obtain transition probabilities for the individual de-excitation channels from the investigated levels.
Branching fraction
Cite
Citations (7)
Radiative lifetimes have been determined for 25 odd-parity levels of neutral Ir using the technique of laser-excited fluorescence from sputtered metal vapour. The lifetimes are combined with branching ratio measurements to derive absolute oscillator strengths for 27 transitions in Ir I. The new lifetime values are a factor of 2.5 higher for two out of three of the only previously reported lifetimes in Ir, while the oscillator strengths are systematically smaller, by factors of up to seven, than the arc emission results of Corliss and Bozman (1962).
Branching fraction
Oscillator strength
Cite
Citations (23)
Branching (polymer chemistry)
Branching fraction
Cite
Citations (8)
Radiative lifetimes, accurate in most cases to ±5%, from time-resolved, laser-induced fluorescence measurements on a slow beam of lutetium atoms and ions are reported for 22 odd-parity levels and 4 even-parity levels of Lu I and 14 odd-parity levels of Lu II. In addition, we report the radiative lifetime of one odd-parity level and an upper bound on the radiative lifetime of a second odd-parity level of Lu III. Experimental branching fractions for Lu I from emission spectra covering the near ultraviolet to the near infrared and recorded using the US National Solar Observatory 1.0 m Fourier transform spectrometer are reported. The branching fractions are combined with the radiative lifetimes to produce 44 experimentally determined transition probabilities or oscillator strengths, accurate generally to ±10%, for Lu I. New theoretical values for Lu I radiative lifetimes and branching fractions from a relativistic Hartree-Fock calculation that includes core polarization effects are also reported. These experimental and theoretical results, as well as older published results, are compared.
Branching fraction
Lutetium
Parity (physics)
Cite
Citations (58)