A high-pressure mass spectrometric study of ion–molecule reactions in a mixture of CF4 and He

Gas phase ion–molecule reactions of positive He+ ions produced from helium with neutral carbon tetrafluoride have been studied. The measurements were made with a quadrupole mass spectrometer with a high-pressure ion source. The fractional abundance Ii/∑Ii of dominant ions CF3+, CF2+ and helium ions has been determined as a function of the (1% CF4 and 99% He) gas mixture pressure (in the range 1.33–31.92 Pa) and of the repeller electrode potential (ranging from 3 to 10 V).