A time-dependent postextraction differential acceleration (PEDA) potential was used to
temporally focus increasingly heavy ions in a stigmatic imaging mass spectrometer,
allowing them to be imaged with high mass and spatial resolutions over a broad
mass-to-charge (
m
/
z
) range. By applying a linearly
rising potential to the ion extraction electrode, sequential
m
/
z
ratios were subjected to a changing electric
field, allowing their foci to coincide at the detector. Using this approach, at least
75% of the maximum mass resolution was obtained over a 300–600 Da range when the
ion microscope was focused around 450 Da, representing more than a 10-fold increase over
the conventional single-field PEDA method.