Fig. 3. Spectroscopic characterization of the molecular species.
a, Optical emission spectra recorded at position OES in Fig. 1b for low and high H2 densities. b, In situ gas-phase mass spectroscopy detection at position QMS of most important masses for low and high H2 densities. Vertical dashed lines indicate the time period where the magnetron was switched on and off. All masses have been offset for clarity.