TY  - THES
A1  - Herterich, Jörg
T1  - Pikosekunden-zeitaufgelöste Photoionisation: 2-Methylallyl-Radikal und Pyracen
T1  - Pikosecond-time-resolved photoionisation: 2-Methylallyl-radical and Pyracene
N2  - Die vorliegende Dissertation untersucht fünf unterschiedliche Moleküle hinsichtlich ihrer Geometrien im Grund- und angeregten Zustand sowie deren Dynamik
nach elektronischer Anregung. Der Fokus liegt dabei unter anderem auf Pi-konjugierten Systemen, die über eine zusätzliche aliphatische Einheit verbrückt (Paracyclophan-
Derivate) oder erweitert (Pyracen) sind. Die Paracyclophan-Derivate sind ein ideales Modellsystem um Einsicht in Pi-Pi-Wechselwirkungen zu erlangen. Ein
weiterer Schwerpunkt dieser Arbeit beschreibt die Dynamik des resonanzstabilisierten 2-Methylallyl-Radikals. Die Forschung an solchen kleinen Kohlenwasserstoff-Radikalen ist wichtig, da auf deren Grundlage Modelle entwickelt werden können, die zum Beispiel helfen, den Verbrennungsprozess aufzuklären. Aufgrund ihrer Instabilität sind solche kleinen Kohlenwasserstoff-Radikale nicht einfach zu handhaben und das spektroskopische Vermessen stellt immer eine Herausforderung dar.
N2  - This dissertation examines five different molecules with respect to their geometries in the ground and excited states and their dynamics after electronic excitation. The
focus is on pi-conjugated systems, bridged (paracyclophane derivatives) or Extended (pyracen) by an additional aliphatic moiety. Paracyclophanes are suitable models to study the interaction between pi-systems, in particular the through space coupling.
Moreover, this work focuses on the excited-state dynamics of the B-state of 2-methylallyl (2MA) by time-resolved photoionization with a ps-laser. Research on
resonantly stabilized small radicals such as allyl or methylallyl is not only conducted because of a fundamental interest in reaction dynamics, but also because such radicals can accumulate in a reactive environment and are observed in combustion.
Studies on isolated radicals yield information on their reactions, which are important in kinetic modeling of combustion processes. For example, biodiesel often
contains molecules with C=C double bonds (e.g. fatty acid esters). Abstraction of H-atoms leads to alkylated allyl radicals, because the C-H bonds at the allylic sites
are particularly weak. Due to their instability, such small hydrocarbon radicals are not easy to handle and their spectroscopic measurement is always a challenge.
An innovation in my research was the development of a high-temperature gas cell to transfer the molecules into the gas phase and to record IR-spectra (compatible
with an FT-IR spectrometer), obtaining experimental information on the most stable conformer in the electronic ground state.
KW  - Photoionisation
KW  - Pyracen
KW  - photoionisation
KW  - 2-Methylallyl
KW  - Pump-Probe-Spektroskopie
KW  - pyracene
KW  - 2-methylallyl
KW  - pump-probe-spectroscopy
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-105829
ER  -