Simulations of Mass Spectrometers

Over a period of some 15 years we have developed a simulation program which predicts behavior of ions in ion traps. It has proved to be a most valuable tool in our experimental program dealing with miniature and multiplexed (arrays) ion traps.

  • Simulations of electric fields elucidate understanding of ion motion with the ion trap
  • Ion Trajectory Simulation program (ITSIM) is a generalized ion motion simulation program which allows calculation of mass spectra
  • The calculated fields from within an arbitrary 3D structure are input in ITSIM which simulates ion motion under user-specified conditions
  • ITSIM deals with actual not idealized geometries and fields, it treats multiple ions, it considers collisions in a stochastic fashion and includes inelastic as well as elastic collisions and it allows injection, ejection, MS/MS, and other experiments to be simulated.
  • Simulations provide guidance in the design and optimization of the ion traps used in this lab.




(a) The 3D drawing and corresponding potential plot of an RIT. (b) The experimental and simulated internal EI mass spectra for 1,3-dichlorobenzene using boundary ejection



  • Guangxiang Wu, Meng Yu, William J. Chappell, R. Graham Cooks, Wolfgang R. Plass and Zheng Ouyang, "Ion Trajectory Simulation for Electrode Configurations with Arbitrary Geometries", Journal of the American Society of Mass Spectrometry2006, 254, 1-2, 53-62, doi: 10.1016/j.ijms.2006.05.007.
  • Guangxiang Wu, R. Graham Cooks and Zheng Ouyang, "Geometry Optimization for the Cylindrical Ion Trap: Field Calculations, Simulations and Experiments", International Journal of Mass Spectrometry2005, 241 (2-3), 119-132, doi: 10.1016/j.ijms.2004.12.004