Complex surface-adsorbed molecules and molecular structures are attracting much interest due to possible applications, e.g., controlled surface functionalization and on-surface synthesis of new materials. Although detailed information on the structure of such surface-adsorbed molecules is routinely obtained, e.g., by means of scanning probe microscopy, little information is available on the exact chemical composition. This is due to the fact that standard surface sensitive analytical techniques such as XPS or SIMS typically fall short of detecting the chemical composition of larger organic molecules on surfaces.
In order to fill this gap, we have developed an ultra-soft mass spectrometry technique based on desorption/ionization induced by neutral SO2 clusters (DINeC). During cluster-surface impact, the SO2 clusters both provide the energy for the desorption and serve as a transient matrix in which the analyte molecules are dissolved. As a consequence, desorption/ionization induced by neutral SO2 clusters proceeds at low cluster energies and the desorbed molecules are efficiently cooled by evaporation of SO2 molecules from the cluster fragment in which the desorbed molecule is dissolved. Thus, DINeC-MS features an in general very soft desorption process leading to fragmentation-free spectra of the analyzed compounds. A variety of different classes of substances, including lipids, peptides, proteins, dyes, and ionic liquids, have been analyzed by means of DINeC-MS, both from organic bulk samples as well as from inorganic substrates on which the molecules were adsorbed in the sub-monolayer to multilayer regime.
DINeC features matrix-free, ultra-soft desorption/ionization which does not require any further sample preparation. It can be applied in real time for the investigation of the reaction kinetics of complex (on-surface) reactions. In order to fully exploit the potential of this method, we are constantly extending the field of applications and we are looking forward to collaborations which will benefit from the advantages of DINeC-MS.
Cluster-induced desorption for ultra-soft mass spectrometry
- Scientific exchange and discussion
- Initiating research cooperations in the field soft mass spectrometry – application of soft mass spectrometry