An Investigation of CH- and CHO-bearing Molecules with the ROSINA-DFMS

Schuhmann, Markus (2020). An Investigation of CH- and CHO-bearing Molecules with the ROSINA-DFMS (Submitted). (Dissertation, Universität Bern, Physikalisches Institut, Philosophisch-naturwissenschaftliche Fakultät)

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The purpose of this work was the analysis of comet 67P/Churyumov-Gerasimenko with
regards to CH- and CHO-bearing molecules. By studying these complex organics clues
about the origin of the cometary material and the formation of the Solar System can be
derived.
In order to archive this, first a calibration campaign of the ROSINA-Double Focusing
Mass Spectrometer (DFMS) on CH- and CHO-bearing molecules was performed. The
goal was to reproduce the fragmentation patterns generated by the molecules of interest
inside the ion source of the instrument, as well as to investigate the impact on the
instrument’s sensitivity on the molecules. The study was conducted using the prevalent
DFMS operational settings of 200 μA filament emission and 45 eV ionization energy, in
combination with a multichannel plate (MCP) as detector.
The results have been combined with data collected from comet 67P/Churyumov-
Gerasimenko, in order to obtain the first detailed identification and quantification
campaign of the CH- and CHO-bearing molecules in its coma. In such way the cometary
bulk abundances could be derived for many organic molecules. This has been repeated
at altered mission phases, to determine the impact of location, season, and heliocentric
distance on the results. The outcome was summarized in two publications, which are
included in this work.
The work is organized as follows: The first chapter gives a brief overview on the Rosetta
mission and its target, comet 67P/Churyumov-Gerasimenko. The next chapter looks at
the ROSINA-DFMS. This also includes the DFMS data analysis. The third chapter
concentrates on comets in general. Chapter 4 discusses the DMFS calibration procedure
in detail. The results of the calibration campaign can be found in chapter 5. In addition,
chapter 6 shows the results of the DFMS space data analysis, including two publications
and a further comparison of the results to other comets and the interstellar medium.
Chapter 7 provides a conclusion and outlook. An appendix and a full list of references
are included at the end of this work.

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