Atomic data from the Iron Project. LIII. Relativistic allowed and forbidden transition probabilities for Fe XVII

TL;DR

This paper provides an extensive set of relativistic transition probabilities for Fe XVII, including allowed and forbidden transitions, significantly expanding the available atomic data for this ion.

Contribution

It presents the most detailed calculations to date for Fe XVII, including over 26,000 allowed and 3,000 forbidden transition probabilities using advanced relativistic methods.

Findings

Over 26,000 allowed (E1) transition probabilities computed.

Approximately 3,000 forbidden transition probabilities obtained.

Energy levels identified with high accuracy, matching observed data within 1%.

Abstract

An extensive set of fine structure levels and corresponding transition probabilities for allowed and forbidden transitions in Fe XVII is presented. A total of 490 bound energy levels of Fe XVII of total angular momenta 0 <= J <= 7 of even and odd parities with 2 <= n <= 10, 0 <= l <= 8, 0 <= L <= 8, and singlet and triplet multiplicities, are obtained. They translate to over 2.6 x 10^4 allowed (E1) transitions that are of dipole and intercombination type, and about 3000 forbidden transitions that include electric quadrupole (E2), magnetic dipole (M1), electric octopole (E3), and magnetic quadrupole (M2) type representing the most detailed calculations to date for the ion. Oscillator strengths f, line strengths S, and coefficients A of spontaneous emission for the E1 type transitions are obtained in the relativistic Breit-Pauli R-matrix approximation. A valus for the forbidden transitions are obtained from atomic structure calculations using codes SUPERSTRUCTURE and GRASP. The energy levels are identified in spectroscopic notation with the help of a newly developed level identification algorithm. Nearly all 52 spectroscopically observed levels have been identified, their binding energies agreeing within 1% with our calculation. Computed transition probabilities are compared with other calculations and measurement. The effect of 2-body magnetic terms and other interactions is discussed. Present data set enhances by more than an order of magnitude the heretofore available data for the transition probabilities of Fe XVII.