On the contrary, Chem-I between H2 and CO exhibited such dependence. Figure compares the mass spectra with and without H2 in CO at 70 eV. Distinct from Chem-I scrambling being seen at 28 eV (Figure ), this issue was not observed at 70 eV. At 70 eV, the ratio of IM12-C/IM28-CO was significantly higher than at 28 eV, indicating a more severe CO fragmentation.