MATRIX-ASSISTED LASER DESORPTION IONIZATION BY 2 COLLINEAR SUBTHRESHOLD LASER-PULSES/

Two nitrogen laser pulses of subthreshold irradiance were used to achi eve matrix-assisted laser desorption/ionization in a collinear configu ration, Optimum laser pulse delay times yielding maximum guest ion int ensities were determined for four different matrices between 4.2 ns fo r 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 ma gnitude improvement in spatial and time resolution over post-ionizatio n experiments. (C) 1997 by John Wiley & Sons, Ltd.