Massenspektrometrische Untersuchungen und Simulationen zur Verbesserung des Auflösungsvermögens und der Weiterentwicklung einer Cassini-Ionenfalle
In modern mass spectrometry ion traps are very popular. Due to their construction and the use of high performance vacuum equipment, ion traps like the Orbitrap or the FT-ICR-experiment yield us very highly resolved mass spectra. Besides these popular ion traps, more traps can be realized using the same mathematical expression. One of them is the Cassinian ion trap. The aim of this work is to present a way of taking one of the only existing and working Cas-sinian ion traps and increasing its resolving power. To achieve this goal the capabilities and characteristics of the existing design need to be evaluated. The first part of this work presents the results of this characterization by determining the ideal setup and by giving examples for diffe-rent experimental analytical problems. After characterization the limits of this first design were quite obvious. Apparently a redesign of the Cassinian ion trap's geometry was necessary. For this purpose computer models using SimIon, COMSOL and Inventor were created. A way was developed to calculate the mass spec¬trum of an ionic species inside the ion trap. By using the Shockley-Ramo theorem and the Green’s reciprocity theorem we computed an algorithm to calculate the induced signal inside the measuring electrodes of the ion trap. Utilizing this algorithm the resolving power of any trap geometry can be calculated. Weighting the quality of the new trap designs by their theoretical resolving power, more efficient versions of the Cassinian trap were determined. Subsequently, the most promising design was manufactured. Finally, this work presents the first measurements on the new so called High-Field-Cassinian ion trap and its characteristics. The resolving power was increased by 29.1% (at m/z 443) with this new setup. This presented way of redesigning and optimizing a mass spectrometer can now be adopted to improve any given mass spectrometer in the future.
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