Patent ID: 6703608
Filing Date: 2004-03-09
Classification: H01J

Abstract:
Method for acquiring spectra of daughter ions produced by decay from parent ions in a time-of-flight mass spectrometer comprising the following steps:a) generating or introducing in an ion source an assembly of ions having an initial kinetic energy spread, b) accelerating the ions into a first field-free drift path of the mass spectrometer, c) letting a fraction of the ions decay into daughter ions during their flight in this drift path, d) passing the parent ions to be analyzed, together with their daughter ions having equal velocity, into a potential lift cell, e) raising the potential of the lift cell to high voltages during the passage of the ions, f) letting the ions pass into an adjacent region, where the ions exhibit a spatial distribution correlated with their velocities essentially caused originally by the different initial kinetic energies in the ion source, g) switching on, after a predetermined delay with respect to the potential raise in the lift cell, a first post-acceleration field in this first adjacent region, thereby starting the acceleration of the ions and generating a space-velocity correlation focusing effect for the ions that is adjusted by setting the delay time and the acceleration field strength to the location of an ion detector, h) post-accelerating, if necessary, the ions in one or more subsequent post-acceleration regions and thereby accelerating the ions into a second field-free drift path, i) measuring the flight times of the ions which they need to arrive at the ion detector, and j) analyzing the ions with respect to their masses by their flight times.