CII 157 µm transition (blue) and stacked spectra of the HeNα and CNα RRLs with N=39−42 and 44 (black) towards clump HG (Her 36). The velocity scale of the RRLs is computed based on the rest frequency of the CNα lines. The Gaussians fitted to the RRLs are displayed in red. The temperature scale of the 158 µm CII fine structure transition is divided by 2000 to compare it with the RRLs.