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Molecular dynamics simulations of MALDI: laser fluence and pulse width dependence of plume characteristics and consequences for matrix and analyte ionization
Author(s) -
Knochenmuss Richard,
Zhigilei Leonid V.
Publication year - 2010
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1732
Subject(s) - fluence , chemistry , ionization , ion , nanosecond , analyte , laser , plume , atomic physics , matrix (chemical analysis) , yield (engineering) , analytical chemistry (journal) , polyatomic ion , optics , physics , chromatography , thermodynamics , organic chemistry
Molecular dynamics simulations of matrix‐assisted laser desorption/ionization were carried out to investigate laser pulse width and fluence effects on primary and secondary ionization process. At the same fluence, short (35 or 350 ps) pulses lead to much higher initial pressures and ion concentrations than longer ones (3 ns), but these differences do not persist because the system relaxes toward local thermal equilibrium on a nanosecond timescale. Higher fluences accentuate the initial disparities, but downstream differences are not substantial. Axial velocities of ions and neutrals are found to span a wide range, and be fluence dependent. Total ion yield is only weakly dependent on pulse width, and consistent with experimental estimates. Secondary reactions of matrix cations with analyte neutrals are efficient even though analyte ions are ablated in clusters of matrix. Copyright © 2010 John Wiley & Sons, Ltd.