Figure 1: Experimental emission spectra.
From: Investigation of femtosecond collisional ionization rates in a solid-density aluminium plasma

Experimentally measured Kα intensities as a function of the spectrally resolved emission (horizontal axis) and X-ray pump photon energy (vertical axis)23,24. Emission from Al charge states 4+ to 8+ are marked, with the black windows showing the regions of the experimentally measured K-edges, and the red windows showing regions of the spectrum where collisional effects are the main contributor to the emission from a specific line.