Comparison of Ion Trajectories in Vacuum and Viscous Environments using SIMION: Insights for Instrument Design

Journal Article · Mon Oct 01 04:00:00 EDT 2007 · International Journal of Mass Spectrometry

DOI:https://doi.org/10.1016/j.ijms.2007.07.008· OSTI ID:920714

Dahl, David A; McJunkin, Timothy R; Scott, Jill R

Understanding ion trajectories in electrostatic and magnetic fields is necessary for designing many scientific instruments. Modeling of ion motion in vacuum has been possible for over a decade with SIMION software, which has been highly exploited to advance instrumentation, especially mass spectrometers. Simulations of ions within a viscous media, such as in ion mobility spectrometers, has only recently been possible with the advent of the statistical dynamics simulation user program for SIMION 7.0. Key insights into the difference in ion behavior in vacuum and viscous environments are reported for electrostatic refraction, motion through grids, and magnetic fields. The loss of kinetic energy limits options for controlling ion motion in viscous conditions. For refraction, only accelerating methods (converging or diverging) are possible in viscous regimes. Motion of ions around wires in grids also has more severe consequences in viscous conditions than in vacuum. For magnetic fields, a “rule-of-thumb” that an ion must be able to complete ~25 % of its cyclotron radius between collisions for the magnetic field to affect the ion motion. The difference in ion behavior is governed by the fact that kinetic energy of ion motion is retained in vacuum, but lost to collisions with the bath gas in viscous atmospheres. Because of the loss of kinetic energy, ion behavior in electrostatic and magnetic fields under viscous conditions is dramatically different than in vacuum.

• Research Organization: Idaho National Laboratory (INL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC07-99ID13727
• OSTI ID: 920714
• Report Number(s): INL/JOU-07-12574
• Journal Information: International Journal of Mass Spectrometry, Journal Name: International Journal of Mass Spectrometry Journal Issue: 1 - 3 Vol. 266
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CYCLOTRONS
DESIGN
ELECTROSTATICS
ION MOBILITY
Ion mobility spectrometry
Ion trajectories
KINETIC ENERGY
MAGNETIC FIELDS
MASS SPECTROMETERS
Mass spectrometry
REFRACTION
SDS
SIMION
SIMULATION
SPECTROMETERS
TRAJECTORIES
Vacuum
Viscous