Matrix-assisted Laser Desorption/Ionization by Two Collinear Subthreshold Laser Pulses

Abstract

Two nitrogen laser pulses of subthreshold irradiance were used to achieve matrix-assisted laser desorption/ionization in a collinear configuration. Optimum laser pulse delay times yielding maximum guest ion intensities were determined for four different matrices between 4.2 ns for sinapinic acid (SA) and 12.5 ns for 2,5-dihydroxybenzoic acid (DHB). The signal decay times followed an opposite trend to the position of maxima, DHB being the fastest decaying (1.1 ns) and SA the slowest (9.8 ns). Collinear subthreshold experiments allow for a two orders of magnitude improvement in spatial and time resolution over post-ionization experiments. © 1997 John Wiley & Sons, Ltd.