Time aberrations of uniform fields: An improved reflectron mass spectrometer for an atom-probe field-ion microscope

The mass resolution of the atom-probe field-ion microscope is limited by the time resolution of the ion-separating spectrometer. Time aberrations of uniform fields are investigated in general in order to characterize the optimal performance of high-transmission, high-mass resolution, multistage reflectron lenses. Correction of higher order time aberrations greatly improves the mass resolution. For an ion beam with an energy distributed uniformly about some nominal energy, E0±dE, mass resolutions (base width) of m/dm=848, 1344, 2151, 3571 can be achieved for single-, double-, triple- and quadruple-stage reflectron mass spectrometers when dE=0.1E0. A unique design example employing both second- and third-order time correction is given for an atom-probe field-ion microscope.