Infrared data confirming the formation of OCS from CO, H₂S, and H atoms. Panel a: spectrum collected after deposition of CO + H₂S + H (experiment 1, red) together with the control experiment without H atoms (experiment 2, gray) and the isotope-labeled experiment with ¹³C¹⁸O (experiment 3, blue). Small features assigned to ¹³CO and ¹²CO are due to minor contaminations from the gas bottle (respectively, ~4% and ~2% with respect to ¹³C¹⁸O). Panel b: infrared spectra acquired during TPD following the deposition of experiment 1. The spectrum in dark red (upper) is taken at ~70 K, and the one in light red (lower) is taken at ~100 K. Panel c: same as panel b, but for the isotope-labeled experiment. In all panels, only the relevant frequency range is shown and the spectra are offset for clarity.