May 24th, 2010

Aaron Robinson, NCSAAPT S11

An EJS Simulation of a Mass Spectrometer
Presented at the 2011 Spring Meeting of NCSAAPT

This simplistic model of a cubic ion trap is designed to introduce scientists and students to ion cyclotron resonance phenomenon. By employing Easy Java Simulations (EJS), we were able to generate a 3-D model of a cubic ion trap used for Fourier Transform Ion Cyclotron Resonance Mass Spectrometry. By combining Newton’s 2nd law of motion with the Lorentz Force, we gain the theoretical expression of “ion cyclotron frequency”. When this equation is combined with the Lorentz force, we can create an instrument that, given a constant magnetic field and the appropriate electric fields for trapping and excitation, will trap and excite a target ion. While the present version of the model does not currently calculate the Fourier transform of the data generated to return the m/z ratio of the ions, it models all the physical aspects that lead to the discrete time voltage signal that is transformed into m/z spectra.