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Photochemical versus thermal mechanisms in matrix-assisted laser desorption/ionization probed by back side desorption

Abstract:

The contribution of photochemical and thermal effects in the formation and ejection of biomolecular ions in matrix-assisted laser desorption/ionization; (MALDI) is studied by comparing desorption from one-and-the-same sample in two incident laser geometries - irradiating the sample front, or irradiating the back side through a 2000 Å gold layer. Such a set-up results in the efficient decoupling of photoexcitation from thermal processes. Our results indicate that laser-induced photochemistry, e.g. charge transfer reactions between electronically-excited matrix molecules and the analyte, plays a major role in the MALDI process. © 1996 by John Wiley & Sons, Ltd.