Deceleration of high-energy matrix-assisted laser desorption/ionization ions in an open cell for Fourier transform ion cyclotron resonance mass spectrometry

A new method of ion deceleration in a Fourier transform ion cyclotron reson ance (FTICR) open cell is described that improves the performance of FTICR- MS instruments equipped with an internal source for laser desorption/ioniza tion. Ion deceleration occurs in the front trapping cylinder of an open cyl indrical cell. Decelerating voltages up to 100 V can be applied for 10-500 mus to the front cylinder during ion introduction. The deceleration field i s uniformly distributed along the cylinder length giving a 'smooth' deceler ation, which means that the deceleration is effective over a large time int erval and a large m/z range. This results in improved trapping efficiency o f high-energy ions. We demonstrate efficient trapping of high (m/z 66 kDa) mass ions and the possibility to reduce the width of the kinetic energy dis tribution of MALDI ions with this arrangement. Copyright (C) 2001 John Wile y & Sons, Ltd.