@unpublished{RoederPetersenIssleretal.2019, author = {R{\"o}der, Anja and Petersen, Jens and Issler, Kevin and Fischer, Ingo and Mitric, Roland and Poisson, Lionel}, title = {Exploring the Excited-State Dynamics of Hydrocarbon Radicals, Biradicals and Carbenes using Time-Resolved Photoelectron Spectroscopy and Field-Induced Surface Hopping Simulations}, series = {The Journal of Physical Chemistry A}, journal = {The Journal of Physical Chemistry A}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-198734}, year = {2019}, abstract = {Reactive hydrocarbon molecules like radicals, biradicals and carbenes are not only key players in combustion processes and interstellar and atmospheric chemistry, but some of them are also important intermediates in organic synthesis. These systems typically possess many low-lying, strongly coupled electronic states. After light absorption, this leads to rich photodynamics characterized by a complex interplay of nuclear and electronic motion, which is still not comprehensively understood and not easy to investigate both experimentally and theoretically. In order to elucidate trends and contribute to a more general understanding, we here review our recent work on excited-state dynamics of open-shell hydrocarbon species using time-resolved photoelectron spectroscopy and field-induced surface hopping simulations, and report new results on the excited-state dynamics of the tropyl and the 1-methylallyl radical. The different dynamics are compared, and the difficulties and future directions of time-resolved photoelectron spectroscopy and excited state dynamics simulations of open-shell hydrocarbon molecules are discussed.}, language = {en} } @unpublished{RoederHumeniukGiegerichetal.2017, author = {R{\"o}der, Anja and Humeniuk, Alexander and Giegerich, Jens and Fischer, Ingo and Poisson, Lionel and Mitric, Roland}, title = {Femtosecond Time-Resolved Photoelectron Spectroscopy of the Benzyl Radical}, series = {Physical Chemistry Chemical Physics}, journal = {Physical Chemistry Chemical Physics}, doi = {10.1039/C7CP01437F}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-159474}, year = {2017}, abstract = {We present a joint experimental and computational study of the nonradiative deactivation of the benzyl radical, C\(_7\)H\(_7\) after UV excitation. Femtosecond time-resolved photoelectron imaging was applied to investigate the photodynamics of the radical. The experiments were accompanied by excited state dynamics simulations using surface hopping. Benzyl has been excited at 265 nm into the D-band (\(\pi\pi^*\)) and the dynamics was probed using probe wavelengths of 398 nm or 798 nm. With 398 nm probe a single time constant of around 70-80 fs was observed. When the dynamics was probed at 798 nm, a second time constant \(\tau_2\)=1.5 ps was visible. It is assigned to further non-radiative deactivation to the lower-lying D\(_1\)/D\(_2\) states.}, language = {en} } @article{HirschPachnerFischeretal.2020, author = {Hirsch, Florian and Pachner, Kai and Fischer, Ingo and Issler, Kevin and Petersen, Jens and Mitric, Roland and Bakels, Sjors and Rijs, Anouk M.}, title = {Do Xylylenes Isomerize in Pyrolysis?}, series = {ChemPhysChem}, volume = {21}, journal = {ChemPhysChem}, number = {14}, doi = {10.1002/cphc.202000317}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218316}, pages = {1515 -- 1518}, year = {2020}, abstract = {We report infrared spectra of xylylene isomers in the gas phase, using free electron laser (FEL) radiation. All xylylenes were generated by flash pyrolysis. The IR spectra were obtained by monitoring the ion dip signal, using a IR/UV double resonance scheme. A gas phase IR spectrum of para-xylylene  was recorded, whereas ortho- and meta-xylylene were found to partially rearrange to benzocyclobutene and styrene. Computations of the UV oscillator strength  for all molecules were carried out and provde an explanation for the observation of the isomerization products.}, language = {en} }