Design of the Ion Optical Components in a Time-of-flight Mass Spectrometer For The Study of Ultracold Chemistry

The design of ion optical components for a time-of-flight mass spectrometer (TOF-MS) was motivated by the recent interest in the study of chemical reaction resonances. An optimal setting to study these resonances would have reactants with very well defined kinetic energies. The system proposed to accomplish this uses a magneto-optical trap (MOT) to localize and cool atoms to temperatures below 100µK, which act as targets for a beam of cold molecules created using a hexapole Stark guide. The reaction products would then be ionized through resonance-enhanced multiphoton ionization (REMPI) and analyzed with a TOF-MS. Many obstacles were presented by the high voltage hexapole’s close proximity with the TOF-MS electrodes. However, they were overcome by a careful selection of dimensions and active shielding. Adding the MOT brought about other constraints: off-axis ion detection and open aperature extraction plates. The issues that these generated were solved by employing a set of parallel deflection plates and an Einzel lens. Engineering solutions were tested by simulating ion trajectories in SIMION 3D, a commonly used commerical program in mass spectrometer design. To keep solutions financially feasible, a budget constraint of $100,000 was put in place