AN ION EJECTION TECHNIQUE FOR STUDY OF ION-MOLECULE REACTIONS WITH ION CYCLOTRON RESONANCE SPECTROSCOPY

A novel technique involving a straightforward modification of an ion cyclotron resonance spectrometer has been developed which utilizes the excitation of the characteristic oscillatory motion of the ions, due to the trapping field, for ejecting ions from the cyclotron resonance cell. By pulsing the rf ejection field and referencing the detection system to the pulsing frequency, a spectrum of ions whose number density is modulated by the pulsed ejection field is obtained. This is directly applicable in studying ion-molecule reactions for the determination of product ion distributions, even when other processes, such as direct ionization or concurrent ion-molecule reactions, contribute to product ions of interest. © 1969 The American Institute of Physics.