Phase-Shifting Acceleration of Ions in an Ion Cyclotron Resonance Spectrometer:  Kinetic Energy Distribution and Reaction Dynamics

1997 ◽  
Vol 101 (26) ◽  
pp. 4745-4752 ◽  
Author(s):  
Stephen L. Craig ◽  
John I. Brauman
Keyword(s):  
Kinetic Energy ◽  
Energy Distribution ◽  
Cyclotron Resonance ◽  
Reaction Dynamics ◽  
Phase Shifting ◽  
Kinetic Energy Distribution ◽  
Ion Cyclotron Resonance ◽  
Ion Cyclotron

Theory of Ion Cyclotron Resonance

1974 ◽  
Vol 52 (5) ◽  
pp. 436-455 ◽  
Author(s):  
M. Bloom ◽  
M. Riggin
Keyword(s):  
Kinetic Energy ◽  
Cyclotron Resonance ◽  
Ad Hoc ◽  
Rectangular Cross Section ◽  
Equations Of Motion ◽  
Average Kinetic Energy ◽  
Ion Cyclotron Resonance ◽  
Cyclotron Motion ◽  
Ion Cyclotron ◽  
Energy Dependent

A theoretical analysis is given of the most commonly used type of ion cyclotron resonance (ICR) spectrometer, which has a cell of rectangular cross section. Though the equations of motion of the ions in this cell are extremely nonlinear, it has been possible to simplify the analysis by exploiting the facts that the longitudinal oscillations in the trapping potential are approximately decoupled from the cyclotron motion and that the cyclotron frequency [Formula: see text] the trapping oscillation frequency [Formula: see text] the spread of instantaneous cyclotron frequencies in the trap. A method is described for constructing an ensemble of ions appropriate to the mechanism of ion production and to the various drift and trapping voltages employed in the ICR cell. Line shapes are calculated in the collisionless regime. An ad hoc "average ion" model is presented, which simplifies the analysis of the spatial distribution of the ions through the dependence of the effective ICR frequency and line width on cell voltages and dimensions. Finally, an explicit distribution function is derived for the ion kinetic energy in the cell. The effect of a uniform RF electric field at resonance is shown to increase not only the average kinetic energy, but the spread of energies as well. A substantial spread of energies is also produced by the trapping oscillations. The breadth of the kinetic energy distribution complicates the interpretation of energy dependent processes using ICR under conditions normally used up to now. Some improved techniques for the study of energy dependent cross sections are proposed.

Ion Cyclotron Resonance Collision Frequencies of Alkali Ions in Rare Gases

1974 ◽  
Vol 52 (17) ◽  
pp. 1683-1693 ◽  
Author(s):  
M. Riggin
Keyword(s):  
Distribution Function ◽  
Energy Distribution ◽  
Cyclotron Resonance ◽  
Particle Density ◽  
Energy Distribution Function ◽  
Ion Cyclotron Resonance ◽  
Zero Field ◽  
Ion Cyclotron ◽  
Oscillating Electric Field ◽  
Ionic Energy

An ion cyclotron resonance (ICR) spectrometer was used to estimate collision frequencies of K+ and Na+ ions at near thermal velocities in helium and argon gases. The reduced zero field d.c. drift mobilities were found to be 11.4 and 40.7 cm2 PMU1/2/V s for 39K+ in Ar and He respectively and 11.6 and 42.8 cm2 PMU1/2/V s for Na+ in these gases. The effect of ion-neutral collisions on the energy distribution function for ions at resonance with an oscillating electric field is discussed and the average ionic energy as a function of neutral particle density obtained. In deriving the ICR line shape and ionic energy distribution function it is assumed that the mean time between momentum changing collisions is independent of the relative ion–neutral velocity.

Sign in / Sign up

Export Citation Format

Share Document