Energy levels and radiative rates for transitions in Mg-like iron, cobalt and nickel

Atomic data and spectral line intensities for Ni XVII

“…FF: [21]. for these the Froese Fischer [21] results show slightly larger departures from the present results and those obtained by Aggarwal et al [26]. The lifetimes calculated using our A values are in excellent agreement with those provided by Aggarwal et al [26], with differences below 5% for almost all the levels with only nine exceptions, for which differences range between 6% and 25% at maximum.…”

“…The most complete calculation of atomic level energies is by Aggarwal et al [26] who carried out extensive calculations with large atomic models using three different suites of codes (CIV3, GRASP, and FAC). Our results agree with their FAC calculations, which they indicate as the most reliable, to better than 0.02% with only three exceptions, whose differences are in the range of $0.03-0.06%.…”

“…Laboratory measurements from many different devices provided line wavelengths [7][8][9][10][11][12][13][14][15] and level lifetimes [16][17][18][19]. A host of calculations have been performed to determine the radiative transition rates of an increasingly larger number of energy levels [20][21][22][23][24][25][26], but calculations of collisional excitation rates have been surprisingly scarce. Moreover, collision rates calculations were restricted to a small number of levels [27][28][29][30], so that the soft X-ray emission of many lines from the n = 3 complex as well as from the n = 4,5 configurations were not included.…”

Energy levels, radiative rates and electron impact excitation rates for transitions in Fe xiv

“…However, such comparisons are only desirable, and are not a fully sufficient test to assess accuracy, as different calculations (or combinations of configurations) may give comparable f-values in the two forms, but entirely different results in magnitude. Generally, the two forms agree satisfactorily for strong transitions, but differences can sometimes be substantial even for some very strong transitions, as demonstrated through various examples by Aggarwal et al (2007). Nevertheless, R is within 0.2 of unity for most (comparatively strong) transitions, and significant departures are for only the weaker ones, such as the last 6 listed in Table 3.…”

“…This is further confirmed by the Avalues from our larger GRASP2 calculations with 332 levels, also listed in Table 3. Therefore, the inclusion of CI is important, but only up to a certain extent, mainly when the levels closely interact among themselves, as also discussed earlier by Aggarwal et al (2007) for three Mg-like ions. Another useful criterion to assess the accuracy of radiative rates is the ratio (R) of the velocity and length forms of the Svalues, included in Table 3.…”