SIMBAD references

We reanalyzed interstellar Cl I and Cl II spectra acquired with the Copernicus satellite. The directions for this study come from those of Crenny & Federman and sample the transition from atomic to molecular-rich clouds where the unique chemistry leading to molecules containing chlorine is initiated. Our profile syntheses relied on up-to-date laboratory oscillator strengths and component structures derived from published high-resolution measurements of K I absorption that were supplemented with Ca II and Na I D results. We obtain self-consistent results for the Cl I lines at 1088, 1097, and 1347 Å from which precise column densities are derived. The improved set of results reveals clearer correspondences with H₂ and total hydrogen column densities. These linear relationships arise from rapid conversion of Cl⁺ to Cl⁰ in regions where H₂ is present.