postsource decay

Postsource decay (PSD) processes are ion dissociations that occur  within the drift region of a time-of-flight mass analyzer.  After initial ion formation and acceleration out of the sourc  into the flight tube, ions may dissociate or neutralize. In a  linear time-of-flight instrument, these fragment ions and  neutral species reach the detector at the same time as the  precursor ions from which they are formed. However, these  reactions can be specifically studied by using a reflectron  (adjusting the ratio of accelerating to reflectron voltages in a  stepwise manner) to bring fragment ions formed in post-  source decay processes into focus at the detector.