Flare-kernel spectra from the region inside the green rectangle in Fig. 10: (left-middle) the spectrogram of the region marked with a green rectangle in Fig. 10, with before (left-top) and after (left-bottom) spectrograms. The right panels show the spectra (solid) and their fits (dashed) at the positions indicated by the green lines in the left panel. The vertical solid lines give the rest wavelength of Fe xxi  and the vertical dashed-dot lines give the rest wavelength of C i line. The green solid line is the background, the blue dashed line is the background + Fe xxi line fit, and the red dashed line is the background + C i line fit.