title: Kinetic energy of free electrons affects MALDI positive ion yield via capture cross-section.
abstract: A method for enhancing positive analyte ion signal in MALDI is described. The idea is based on influencing the kinetic energy of free electrons emitted from the organic/metal interface. It has been recently shown that free electrons in MALDI have energies around 1 eV. This energy is close to the maximum capture cross-section of most common MALDI matrices, leading to the efficient formation of negative matrix ions. This results in the reduction of the positive analyte ion yield. The effect can be minimized by shifting the kinetic energy of the electrons away from the maximum of the matrix capture cross-section by choosing a different substrate material.
authors.affiliation: Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland.
authors.forename: Maxim
authors.initials: M
authors.lastname: Dashtiev
authors.forename: Vladimir
authors.initials: V
authors.lastname: Frankevich
authors.forename: Renato
authors.initials: R
authors.lastname: Zenobi
mesh_terms: D004583:Electrons; D007700:Kinetics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*