Multi‐electron‐capture processes by C4+ from CH4, C2H6, C3H8 and n‐C4H10 in the energy range 0.7–400 eV u−1

Charge-changing cross-sections σ43, σ42 and σ41 of C4+ injected into CH4, C2H6, C3H8 and n-C4H10 were measured in the energy range 0.7–400 eV u−1. A tandem mass spectrometer system with an ion source of the EBIS type (Mini-EBIS) and a collision cell consisting of an octupole ion beam guide was used. It is a significant feature that both the magnitude and energy dependence of the cross-sections obtained showed very little target dependence for all the hydrocarbon targets studied. Another feature is that σ41 is very close to σ42, and they become flat at low energy, in contrast to the case with an argon target which was studied as a reference. This implies that multi-electron-capture processes become dominant in low-energy collisions with hydrocarbon molecules.