TY  - JOUR
A1  - Reusch, Engelbert
A1  - Holzmeier, Fabian
A1  - Gerlach, Marius
A1  - Fischer, Ingo
A1  - Hemberger, Patrick
T1  - Decomposition of Picolyl Radicals at High Temperature: A Mass Selective Threshold Photoelectron Spectroscopy Study
JF  - Chemistry - A European Journal
N2  - The reaction products of the picolyl radicals at high temperature were characterized by mass‐selective threshold photoelectron spectroscopy in the gas phase. Aminomethylpyridines were pyrolyzed to initially produce picolyl radicals (m /z =92). At higher temperatures further thermal reaction products are generated in the pyrolysis reactor. All compounds were identified by mass‐selected threshold photoelectron spectroscopy and several hitherto unexplored reactive molecules were characterized. The mechanism for several dissociation pathways was outlined in computations. The spectrum of m /z =91, resulting from hydrogen loss of picolyl, shows four isomers, two ethynyl pyrroles with adiabatic ionization energies (IE\(_{ad}\)) of 7.99 eV (2‐ethynyl‐1H ‐pyrrole) and 8.12 eV (3‐ethynyl‐1H ‐pyrrole), and two cyclopentadiene carbonitriles with IE′s of 9.14 eV (cyclopenta‐1,3‐diene‐1‐carbonitrile) and 9.25 eV (cyclopenta‐1,4‐diene‐1‐carbonitrile). A second consecutive hydrogen loss forms the cyanocyclopentadienyl radical with IE′s of 9.07 eV (T\(_0\)) and 9.21 eV (S\(_1\)). This compound dissociates further to acetylene and the cyanopropynyl radical (IE=9.35 eV). Furthermore, the cyclopentadienyl radical, penta‐1,3‐diyne, cyclopentadiene and propargyl were identified in the spectra. Computations indicate that dissociation of picolyl proceeds initially via a resonance‐stabilized seven‐membered ring.
KW  - ionization energy
KW  - photoelectron spectroscopy
KW  - pyrolysis
KW  - radicals
KW  - synchrotron radiation
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-208132
VL  - 25
IS  - 72
ER  - 
TY  - JOUR
A1  - Hirsch, Florian
A1  - Pachner, Kai
A1  - Fischer, Ingo
A1  - Issler, Kevin
A1  - Petersen, Jens
A1  - Mitric, Roland
A1  - Bakels, Sjors
A1  - Rijs, Anouk M.
T1  - Do Xylylenes Isomerize in Pyrolysis?
JF  - ChemPhysChem
N2  - 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.
KW  - biradicals
KW  - high-temperature chemistry
KW  - IR spectroscopy
KW  - pyrolysis
KW  - xylylene
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-218316
VL  - 21
IS  - 14
SP  - 1515
EP  - 1518
ER  -