Left panel: Fe xxiii spectra at the footpoint K1 (pink histogram lines) and K2 (blue histogram line). The blue dashed lines represent the double Gaussian components of the fit and the blue continuous line is the superposition of the two components. Right panel: Fe xxiii spectrum (black histogram line) at the flare loop top (LT, see Fig. 5). The continuous line represents the Gaussian fit. The vertical black lines in the left and right panels indicate the expected rest position of the Fe xxiii line.