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What determines MALDI ion yields? A molecular dynamics study of ion loss mechanisms

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Abstract

Ion recombination in matrix-assisted laser desorption/ionization (MALDI) is as important as any ion formation process in determining the quantity of ions observed but has received comparatively little attention. Molecular dynamics simulations are used here to investigate some models for recombination, including a Langevin-type model, a soft threshold model and a tunneling model. The latter was found to be superior due to its foundations in a widespread physical phenomenon, and its lack of excessive sensitivity to parameter choice. Tunneling recombination in the Marcus inverted region may be a major reason why MALDI is a viable analytical method, by allowing ion formation to exceed ion loss on the time scale of the plume expansion. Ion velocities, photoacoustic transients and pump-probe measurements might be used to investigate the role of recombination in different MALDI matrices, and to select new matrices.

Ablation of a thin MALDI sample as simulated by molecular dynamics. Yellow represents high density, black is low. The laser pulse was incident on the right side

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Acknowledgment

One of the authors (L. V. Z.) acknowledges financial support from the National Science Foundation (Award CMMI-0800786).

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Authors and Affiliations

  1. Tofwerk AG, Uttigenstrasse 22, 3600, Thun, Switzerland

    Richard Knochenmuss

  2. Department of Materials Science and Engineering, University of Virginia, 395 McCormick Road, Charlottesville, VA, 22904-4745, USA

    Leonid V. Zhigilei

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  1. Richard Knochenmuss
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  2. Leonid V. Zhigilei
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Correspondence to Richard Knochenmuss.

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Published in the special issue Analytical Sciences in Switzerland with guest editors P. Dittrich, D. Günther, G. Hopfgartner, and R. Zenobi.

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Knochenmuss, R., Zhigilei, L.V. What determines MALDI ion yields? A molecular dynamics study of ion loss mechanisms. Anal Bioanal Chem 402, 2511–2519 (2012). https://doi.org/10.1007/s00216-011-5194-x

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  • DOI: https://doi.org/10.1007/s00216-011-5194-x

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