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Abstract

When sampled by laser irradiation from a suitable matrix, cationized sugars can be desorbed in far higher yields for longer periods than in experiments which do not employ a matrix. Daughter spectra reveal that Li+ reacts differently from the other alkali ions in that it can catalyse ring opening; collision-induced dissociation then causes successive C[BOND]C cleavage reactions. Selectivity is also exhibited by the substrate; some isomers yield much more intense ion currents with the alkali metals than do others. These findings should contribute to a wider use of laser desorption, including selective examination of mixtures for particular types of compounds, as well as detailed structural studies on individual substances.