atomic data for C-sequence
R-matrix electron-impact excitation data for the C-like iso-electronic sequence
Mao, Junjie; Badnell, N. R.; Del Zanna, G.
Abstract
Emission and absorption features from C-like ions serve as temperature and density diagnostics of astrophysical
plasmas. R -matrix electron-impact excitation data sets for C-like ions in the literature merely cover a few ions,
and often only for the ground configuration. Our goal is to obtain level-resolved effective collision strength over
a wide temperature range for C-like ions from \ion{N}{II} to \ion{Kr}{XXXI} (i.e., N + to Kr 30+ ) with a systematic
set of R -matrix calculations. We also aim to assess their accuracy. For each ion, we included a total of 590 fine-
structure levels in both the configuration interaction target and close-coupling collision expansion. These levels
arise from 24 configurations 2l3nl′ with n=2−4 , l=0−1 , and l′=0−3 plus the three configurations 2s22p5l
with l=0−2 . The AUTOSTRUCTURE code was used to calculate the target structure. Additionally, the R -matrix
intermediate coupling frame transformation method was used to calculate the collision strengths. We compare
the present results of selected ions with archival databases and results in the literature. The comparison covers
energy levels, transition rates, and effective collision strengths. We illustrate the impact of using the present
results on an \ion{Ar}{xiii} density diagnostic for the solar corona. The electron-impact excitation data is archived
according to the Atomic Data and Analysis Structure (ADAS) data class adf04 and will be available in OPEN-
ADAS. The data will be incorporated into spectral codes, such as CHIANTI and SPEX, for plasma diagnostics.
Publication:
eprint arXiv:1912.08466
Pub Date: December 2019 arXiv: arXiv:1912.08466 Bibcode: 2019arXiv191208466M Keywords:
Astrophysics - Solar and Stellar Astrophysics; Astrophysics - High Energy Astrophysical Phenomena; Physics - Atomic Physics