Comprehensive Theory for Ion Cyclotron Resonance Power Absorption: Application to Line Shapes for Reactive and Nonreactive Ions

Abstract

The equation of motion of an ion in an ion cyclotron resonance experiment has previously been shown to be $$d\mathbf{v}\mathrm{\hspace{0.17em}/\hspace{0.17em}dt\hspace{0.17em}=\hspace{0.17em}(}\mathbf{E}\mathrm{q\hspace{0.17em}/\hspace{0.17em}m)\hspace{0.17em}+\hspace{0.17em}[(q}\mathbf{v}{\hspace{0.17em}\times \hspace{0.17em}}\mathbf{B}\mathrm{)\hspace{0.17em}/\hspace{0.17em}m]\hspace{0.17em}-\hspace{0.17em}c}\mathbf{v},$$ where $c$ is the reduced collision frequency. A power absorption expression has been obtained from the complete solution of the above equation which is valid at all pressures. This expression reduces in the appropriate limits to previously derived ICR power absorption expressions which are valid at either high or low pressure. The complete power absorption expression is used to derive ICR line shape expressions for an experimental ensemble of nonreactive ions and for an experimental ensemble of reactive primary, reactive secondary, and nonreactive tertiary ions. The power absorption expressions for the chemically reactive ions are dependent upon the assumed nature of the reactive ion–neutral collisions.