LASER-DESORPTION SUBSTRATE EFFECTS

Information about energy transfer during laser desorption from surface s is important for the theoretical description of the desorption mecha nism and necessary for optimizing applications of laser desorption mas s spectrometry. We present a simple method based on laser multiphoton ionization to estimate the internal energy of a laser-desorbed neutral biomolecule, the amino acid tryptophan. The internal energy of neutra l laser-desorbed molecules affects ion fragmentation as well as the mi nimum ionization energy necessary for detecting tryptophan photoions. Data on tryptophan desorbed from glass, graphite, stainless steel, as well as from a silylized glass substrate, were recorded. The silylatio n of glass reduced the internal energy of desorbed tryptophan dramatic ally. (C) 1997 American Society for Mass Spectrometry.