A CURVED-FIELD REFLECTRON FOR IMPROVED ENERGY FOCUSING OF PRODUCT IONS IN TIME-OF-FLIGHT MASS-SPECTROMETRY

A new type of curved-field reflectron has been developed for the energy focusing of ions formed after initial acceleration in time-of-flight (TOF) mass spectrometers. These include ions generated in the dissociation region of a tandem TOF, as well as metastable decay products formed in the field-free drift region prior to their reflection. Unlike conventional linear-field reflectrons, which focus product ions to different focal lengths that are proportional to the mass (energy) of the fragment, the new curved-field reflectron energy focuses all ions to within a small region near the exit of the reflectron. Thus, the collection of resolved fragment peaks is possible without scanning or stepping the potential gradient of the reflectron, enabling faster acquisition of the production spectrum and, more importantly, true multiplex recording of the spectra from each ionization event. Theoretical considerations of the design are discussed along with an evaluation of collision-induced dissociation data, demonstrating the performance of the new reflectron in a tandem TOF instrument.