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Modelling and experimental validation of a flowing atmospheric pressure afterglow source used for ambient ionization mass spectrometry.

Ambient desorption/ionization mass spectrometry is a new field of mass spectrometry, which is becoming increasingly popular in analytical chemistry. An ion source that is gaining increasing interest for this purpose is the flowing atmospheric pressure afterglow (FAPA). It has two separated regions: the plasma ignition zone and the afterglow, which is generated outside the chamber and where the analytes are introduced. Hence, it allows the analysis of samples in the open, ambient environment. The ions and metastables from the plasma react with air constituents, resulting in the formation of reagent ions, which are then capable of ionizing the analyte of interest. The ions of the analyte material are finally detected by a mass spectrometer. The aim of my project is to identify the main ionization mechanisms in the reagent ion formation. First I will develop a zero-dimensional (0D) chemical kinetics model to describe the plasma chemistry of a helium plasma with air impurities, flowing into humid air, and the formation of reagent and analyte ions. Subsequently I will insert the obtained (and reduced) chemistry set into a 2D fluid model to describe the gas flow dynamics as well as the chemistry of the active plasma region and flowing afterglow, and I will study in detail the ionization pathways for a wide range of conditions. I will validate the model with experiments performed during two research visits at Rensselaer Polytechnic Institute (US).
Date:1 Oct 2017  →  Today
Disciplines:Applied mathematics in specific fields, Classical physics, Physics of gases, plasmas and electric discharges, Analytical chemistry, Pharmaceutical analysis and quality assurance
Project type:Collaboration project