Electron Impact Excitation of N-like Ca XIV

Abstract

Abstract We present a close-coupling R-matrix calculation of the electron impact excitation of N-like Ca XIV. GRASP (general-purpose relativistic atomic structure package) was used to obtain the target states. Level energies are reported for the 272 levels of the target ion. The oscillator strengths and radiative rates were calculated for E1, E2, M1, and M2 transitions among these levels. In order to determine the collision strength, the lowest 84 levels were used as the target model, together with 40 partial waves included in the R-matrix calculation. The effective collision strengths were obtained by integrating the collision strengths over a Maxwellian electron energies distribution. Comparisons were made with our FAC and the LB results by Landi and Bhatia (2005, At. Data Nucl. Data Tables, 90, 177). Good agreements are shown for level energies, oscillator strengths and radiative rates, respectively. As to the collision strength, a mass of resonances appears in the R-matrix results, which are important in the determination of effective collision strengths. The discrepancies of the effective collision strengths between results from the R-matrix and from FAC are discussed. Finally, the effective collision strengths for transitions among the first 84 levels are reported. To test our results, we also compared the predicted line ratio with the observed values.