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MS: Massenspektrometrie

MS 6: Clusters, Molecules, Laser Desorption and MALDI

MS 6.2: Talk

Thursday, April 5, 2001, 16:30–16:45, EB 202

Coupling of Pulsed Hyperthermal Surface Ionization with Time-of-Flight Mass Spectrometry — •Lars Draack and Christian Weickhardt — Lehrstuhl Physikalische Chemie und Analytik, Brandenburgische Technische Universität Cottbus, Erich-Weinert-Str. 1, 03044 Cottbus

Hyperthermal Surface Ionization is an new and soft ionization method for mass spectrometry with some advantageous properties. The degree of fragmentation for organic molecules is small. For some molecules which are important in analytical chemistry like PAH’s, drugs and biomolecules a very high ionization efficiency is obtained. In addition the selectivity can be influenced by varying the velocity of the molecular beam. Further advantages are its easy handling and the low costs.
In order to couple HSI to a time-of-flight mass spectrometer, which is characterized by a short analysis time, high mass resolution, a large mass range and a simple design, two different geometries of ion sources were investigated and compared using volatile substances. The ionization is performed by an interaction of the molecular beam accelerated molecules with a heated rhenium-oxide surface.
For increasing molecular masses the conventional ionization methods show a rapidly decreasing ionization efficiency. In contrast, theoretical examinations of HSI predict an even increasing ionization efficiency when the molecular mass is increased. Thus, we couple HSI and TOF-MS with laser desorption in order to study the HSI behavior of large non-volatile molecules in order to create an efficient and advantageous ionization method for substances of this kind.