A Quadratic-Field Reflectron Time-of-Flight Mass Spectrometer Incorporating Intermediate Temporal Focusing:

A time-of-flight mass spectrometer, using a two-electrode cone-plus-hyperboloid geometry to produce a quadratic reflecting field, has been designed, constructed and tested. The included angle of the cone was 90°. Matrix-assisted laser desorption/ionisation and direct laser desorption/ionisation were the methods used to produce ions. Physical constraints imposed by the geometry of the ion mirror were overcome by the use of ion-bunching to form an intermediate temporal focus. Experimental and ion-optical simulation results are presented, showing the large energy-bandwidth of the quadratic-field reflectron and the effectiveness of ion-bunching as a method of producing a temporal focus at the entrance to the ion mirror.