We calculate the flux of x rays produced by low-energy cosmic-ray nuclei in HI regions. We consider electron capture to excited states by cosmic-ray nuclei of heavy elements, followed by cascades down to the ground state. It is found that the electron-capture processes may yield appreciable line intensities in the range 1-10 keV in the galactic plane.

• Received 28 April 1969

DOI:https://doi.org/10.1103/PhysRevLett.23.597