Thesis defense of Alexander Knodel

This thesis focuses on the coupling of laser desorption with plasma ionization in mass spectrometry for analytical and biomedical applications. A diode laser is used to  trigger thermal desorption of substances from a surface. For this reason, a metal-isolator sandwich structure is developed and conceptually tuned to analytical demands on the basis of a microscope slide, lithography and sputtering. The neutral desorbate is then ionized by a flexible, atmospheric pressure micro plasma and is finally detected by a mass spectrometer. Different analyte classes are investigated to evaluate the method, ranging from analytical standards to complex samples.

These insights are extended to an automated imaging of biological tissue, which requires an adaption of the substrate design. The inherent laser-based and thermal surface effects are intensively studied and optimized to the imaging. As a result, the imaging of biological samples is simplified, faster and can be carried out in ambient air without the need of a chemical matrix, which can be applied to routine analysis in life sciences. The limits of the method are finally evaluated.

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