PT Unknown AU Helle, N TI 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 PY 2022 PU Christian-Albrechts-Universität zu Kiel WP https://macau.uni-kiel.de/receive/macau_mods_00002490 LA en DE REMPI; MATI; Pyridine; Halopyridine; Ethoxylbenzene; Pyridin; Halopyridin; Ethoxybenzol AB 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 ± 4 cm-1 and an adiabatic ionization energy for the D0 state of 65665 ± 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 ± 2 cm-1 and 35064 ± 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 ± 6 cm-1 and 76579 ± 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 ± 9 cm-1 via the one-photon MATI spectrum. PI Kiel ER