@PhdThesis{macau_mods_00002490, author = {Helle, Niklas}, title = {In-Depth Investigations of Ethoxybenzene, 3-Chloropyridine and 3-Fluoropyridine by Means of REMPI and MATI Spectroscopy and Construction of a Tunable VUV Radiation Source}, year = {2022}, publisher = {Christian-Albrechts-Universit{\"a}t zu Kiel}, address = {Kiel}, keywords = {REMPI; MATI; Pyridine; Halopyridine; Ethoxylbenzene; Pyridin; Halopyridin; Ethoxybenzol}, abstract = {Comprehensive understanding of molecular properties and structures in electronically excited or ionic states is quite challenging. An approach to obtain detailed insights jointly utilizes scientific experiments and theoretical models: REMPI and MATI spectroscopy are suitable to map the excited and ionic states, respectively, and Franck-Condon simulations allow for a comparison of the spectra with theory. This approach has been applied to ethoxybenzene, m-chloro- (3-CP) as well as m-fluoropyridine (3-FP). Moreover, a tunable VUV radiation source has been constructed and utilized to record the one-photon MATI spectrum of 3-FP. The results of ethoxybenzene yielded an S1 excitation energy of 36370 {\textpm} 4 cm-1 and an adiabatic ionization energy for the D0 state of 65665 {\textpm} 7 cm-1. Upon electronic excitation and ionization, the C-O-C bond angle increases. The geometry of the first electronically excited and ionic ground state of ethoxybenzene as well as their vibronic structure have been characterized in detail. The pyridine derivatives m-chloro- and m-fluoropyridine were treated with REMPI and MATI spectroscopy for the first time. Their S1 excitation energy has been determined to be 34840 {\textpm} 2 cm-1 and 35064 {\textpm} 2 cm-1, respectively. Both molecules exhibit a distinct vibronic coupling to the S2 and S3 state. The adiabatic ionization energy of the D0 state has been determined to be 75879 {\textpm} 6 cm-1 and 76579 {\textpm} 6 cm-1 for 3-CP and 3-FP, respectively. The ionic ground state of both analytes is subject to a vibronic coupling to the D1 state. Overall, the strength of the vibronic coupling is more pronounced for 3-CP than for 3-FP. Moreover, the adiabatic ionization energy of the D1 state of 3-FP was found to be 77129 {\textpm} 9 cm-1 via the one-photon MATI spectrum.}, url = {https://macau.uni-kiel.de/receive/macau_mods_00002490}, file = {:https://macau.uni-kiel.de/servlets/MCRFileNodeServlet/macau_derivate_00003604/Doktorarbeit_Niklas_Helle.pdf:PDF}, language = {en} }