K-Shell Photoabsorption Studies of the Carbon Isonuclear Sequence

TL;DR

This study computes detailed K-shell photoabsorption cross sections for carbon ions using the R-matrix method, providing insights into resonance features and aiding X-ray spectrum modeling, with results aligning well with some experimental data.

Contribution

The paper presents new R-matrix calculations of K-shell photoabsorption for C I - C IV ions, including resonance features and broadening effects, filling gaps in experimental data.

Findings

Good agreement with existing theoretical results above threshold

Resonance strengths and positions generally match experimental data

Provides detailed cross sections for X-ray spectral modeling

Abstract

K-shell photoabsorption cross sections for the isonuclear C I - C IV ions have been computed using the R-matrix method. Above the K-shell threshold, the present results are in good agreement with the independent-particle results of Reilman & Manson (1979). Below threshold, we also compute the strong 1s -> np absorption resonances with the inclusion of important spectator Auger broadening effects. For the lowest 1s -> 2p, 3p resonances, comparisons to available C II, C III, and C IV experimental results show good agreement in general for the resonance strengths and positions, but unexplained discrepancies exist. Our results also provide detailed information on the C I K-shell photoabsorption cross section including the strong resonance features, since very limited laboratory experimental data exist. The resultant R-matrix cross sections are then used to model the Chandra X-ray absorption spectrum of the blazar Mkn 421.