Mass-correlated pulsed extraction: Theoretical analysis and implementationwith a linear matrix-assisted laser desorption/ionization time of flight mass spectrometer

The pulsed extraction (PE) of ions produced by matrix-assisted laser desorp tion/ionization in time-of-flight mass spectrometers greatly improves mass resolution but, unfortunately, this method is mass dependent. Here we repor t an approach to expand the capabilities of the PE method so as to provide uniform focusing conditions over a wide mass range. Along with an extractio n pulse, an additional pulse is applied to correct the mass dependency of t he standard PE method. We describe the algorithm for derivation of this cor rection pulse waveform, where the first-order focusing conditions are valid all along the mass region of interest. Experimental verification of this m ethod for correction of ion velocities demonstrated better mass resolution than standard PE over a wide mass range. (J Am Soc Mass Spectrom 2000, 11, 841-853) (C) 2000 American Society for Mass Spectrometry.