Master thesis

This thesis describes characterizations and discusses improvements made over the last year of the Cologne Chirped-Pulse Fourier Transform Spectrometer. First, we discuss the theoretical background. The rotational spectroscopy is described in more detail and the technical principle of the spectrometer is explained. Sub- sequently, the experimental setup, including the timing scheme, is described and characterized by noise temperature measurements. At the noise temperature, the heterodyne mixing process is first left out and then integrated. For further char- acterization, the spectrum of carbonyl sulfide is measured and the results are compared to a similar spectrometer described by Brown et al. (2008). In order to improve the setup, several components are investigated and replaced by optimized parts. For example, various window materials are analyzed and new windows are installed in the vacuum chamber. To characterize the molecular beam cooling effect the intensities of carbonyl sulfide with and without supersonic jet are dis- played and an intensity calibration is performed. Finally, a heatable nozzle with a reservoir is constructed and tested. The spectrometer which was used is also described in this publication: M. Hermanns, N. Wehres, F. Lewen, H.S.P. Müller, S. Schlemmer, Rotational spectroscopy of the two higher energy conformers of 2-cyanobutane, Journal of Molecular Spectroscopy, Volume 358, April 2019, Pages 25-36, DOI