Direct measurement of oscillating behavior in Ar(3P) + CH3Cl → Ar + CH3Cl+ + e− ionization cross section by velocity and orientation angle selected collisions

Abstract

The collision energy dependence of the ionization cross section for the Ar(³P) + CH₃Cl → Ar + CH₃Cl⁺ + e⁻ reaction was determined under specific relative orientation using an oriented CH₃Cl beam and time-of-flight measurements. A remarkable resonance-type structure is revealed in the energy dependence of the orientation-angle-resolved Penning ionization cross section. This novel resonance-type structure could be interpreted as a new type “ nuclear-excited Feshbach resonance” in the formation of vibrational excited Rydberg states leading to a competitive dissociative exit channel.