Patent attributes
Apparatus and method are proposed for the strong improvement of dynamic range (DR) of detectors and of data systems for time-of-flight mass spectrometers (TOF MS) with periodically repetitive signals. TOF separated ions are converted into secondary particles, primarily electrons, and the flow of secondary particles is controllably attenuated to sustain the data acquisition system in a counting mode above the electronic noise threshold. The acquisition time is split between at least two time segments, characterized by alternated transmission efficiency SE of secondary particles. Using strong electron suppression (SE«1) is employed for recording intense ion peak, while counting ions with either ADC, or TDC, or ADC with extracting peak centroids. A longer time segment employs an efficient electron transfer (SE=1) for detecting weak ion species. In another independent aspect, an ion-optical element is provided upstream of the ion detector and is configured to deflect, reflect or retard ions such that ions that have been scattered or fragmented in the time of flight region do not impact on the ion detector.
