postsource decayA type of ion dissociation that occurs within the drift region of a time-of-flight (TOF) mass analyser. After initial ion formation and acceleration out of the source and into the flight tube, ions may dissociate or neutralise. In a linear TOF instrument, fragment ions and neutral species reach the detector at the same time as the precursor ions from which they are formed. These reactions can be specifically studied using a reflectron by stepwise adjustment of the ratio of accelerating to reflectron voltages, so as to bring fragment ions formed in postsource decay processes into focus at the detector.
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