Lifetime measurements and calculated transition probabilities in W III

Abstract

New experimental lifetimes for two levels in doubly ionized tungsten, W III, have been obtained using the time-resolved laser-induced-fluorescence technique. Theoretical oscillator strengths obtained from a HFR calculation including the effects of core-polarization are reported for all transitions from levels below E < 70 000 cm −1 and with log g f −2, thus greatly extending our knowledge of the radiative data in W III. Good agreement is found between the calculated lifetimes and the experimental values from this and previous works. These new results fill a gap in the available data for this ion which is expected to play an important role in fusion reactors.

Experimental radiative lifetimes for highly excited states and calculated oscillator strengths for lines of astrophysical interest in singly ionized cobalt (Co ii)

“…The final decay curves and pulse shape were obtained by averaging over 1000 laser pulses. The code DECFIT (Palmeri et al 2008) was then used to extract the lifetimes by fitting a single exponential function convoluted by the measured shape of the second-step laser pulse and a background function to the observed decay. Table 1 gives the wavelengths for the excitation and detection channels used in the single-step measurements.…”

“…The quoted uncertainties are mainly based on the variation between the different measurements (Palmeri et al 2008).…”

The FERRUM project: Experimental transition probabilities from highly excited even 5s levels in Cr ii

“…The measured excitation pulse width (FWHM) was about 3 ns, but since the e 6 D levels were excited in a two-photon process the final analyses of the decay curves utilized the square of the measured pulse, which then had a temporal width of 2 ns. The lifetimes were extracted using a slightly modified version of the program DECFIT (Palmeri et al 2008) by fitting the fluorescence data with a single exponential convoluted with the square of the measured laser pulse and a constant background. A typical example is shown in Fig.…”

Radiative decay rates for W I, W II and W III allowed and forbidden transitions of interest for spectroscopic diagnostics in fusion plasmas

“…More recently, an extensive set of oscillator strengths for W III electric dipole transitions were calculated by Palmeri et al (2008) using the HFR+CPOL method. The accuracy of these new results was assessed through comparisons with the TR-LIF measurements performed by the same authors for two levels belonging to the 5d 3 6p configuration and with the few results of Schultz-Johanning et al (1999).…”

“…The accuracy of these new results was assessed through comparisons with the TR-LIF measurements performed by the same authors for two levels belonging to the 5d 3 6p configuration and with the few results of Schultz-Johanning et al (1999). A very limited sample of transition probabilities is presented in the paper of Palmeri et al (2008) but the complete set of results is included in the DESIRE database (4822 transitions in the wavelength range 83-1494 nm).…”