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PROBING IONIZATION ENERGIES FOR TRACE GAS IDENTIFICATION: THE MICRO PHOTO ELECTRON IONIZATION DETECTOR (PEID)
* 1, 2, 3 , 4 , 3 , 3 , 3 , 3 , 5 , 6 , 6 , 7 , 8
1  Biomaterial Engineering, Hannover Medical School
2  Fraunhofer Institute of Toxicology and Experimental Medicine ITEM, Hannover, Germany
3  DBT GmbH, Würzburg, Germany
4  Fritz-Haber-Institute, Physical Chemistry, Berlin, Germany
5  University of Applied Sciences, Göttingen, Germany
6  Jade University of Applied Sciences, Wilhelmshaven, Germany
7  Universidad de Chile, Departamento de Física, Laboratorio de Superficies, Santiago, Chile
8  Johannes Kepler University, Inst. for Chemical Technology of Inorganic Materials, Linz, Austria
Academic Editor: ettore massera

https://doi.org/10.3390/CSAC2021-10431 (registering DOI)
Abstract:

Micro gas sensors detect the presence of substances, but can hardly identify them. We developed a novel approach of probing referenceable ionization energies. It extends the photoionization principle towards tunable energies via replacement of photons by accelerated photo electrons.

The device comprises UV-LED illumination, an atmospherically stable photoelectron emission layer with a nano-vacuum electronics accelerator realized in thin film technology and charged particle measurement. A voltage variation at the accelerator provides electrons of tunable energies. The resulting system works at high pressures and reaches ambient laboratory air operability. We were able to prove that variable electron energies can be used for VOC detection using ethyl and butyl acetates, methyl mercaptan, alcoholes, DMSO and trichloro ethylene. The signals observed are resulting from ion scattering which overlays the original electron beam current and can be described borrowing from the old models of thyratron electron tubes and ion mobility spectrometers. The energy resolution which has been reached so far is 0,2 eV and is discussed with respect to the achievable performance data that have been estimated on the basis of theoretical considerations.

Keywords: VOC identification; ionization energy; photo emissive materials; ambient pressure; nano vacuum electronics;

 
 
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