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  - Gerlach, Marius
A1  - Monninger, Sophie
A1  - Schleier, Domenik
A1  - Hemberger, Patrick
A1  - Goettel, James T.
A1  - Braunschweig, Holger
A1  - Fischer, Ingo
T1  - Photoelectron Photoion Coincidence Spectroscopy of NCl\(_{3}\) and NCl\(_{2}\)
JF  - ChemPhysChem
N2  - We investigate NCl\(_{3}\) and the NCl\(_{2}\) radical by photoelectron-photoion coincidence spectroscopy using synchrotron radiation. The mass selected threshold photoelectron spectrum (ms-TPES) of NCl\(_{3}\) is broad and unstructured due to the large geometry change. An ionization energy of 9.7±0.1 eV is estimated from the spectrum and supported by computations. NCl2 is generated by photolysis at 213 nm from NCl\(_{3}\) and its ms-TPES shows an extended vibrational progression with a 90 meV spacing that is assigned to the symmetric N−Cl stretching mode in the cation. An adiabatic ionization energy of 9.94 ± 0.02 eV is determined.
KW  - radicals
KW  - photoelectron spectroscopy
KW  - synchrotron radiation
KW  - nitrogen trichloride
KW  - photolysis
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257322
VL  - 22
IS  - 21
ER  - 
TY  - JOUR
A1  - Fischer, Kathrin H.
A1  - Hemberger, Patrick
A1  - Bodi, Andras
A1  - Fischer, Ingo
T1  - Photoionisation of the tropyl radical
JF  - Beilstein Journal of Organic Chemistry
N2  - We present a study on the photoionisation of the cycloheptatrienyl (tropyl) radical, \(C_7H_7\), using tunable vacuum ultraviolet synchrotron radiation. Tropyl is generated by flash pyrolysis from bitropyl. Ions and electrons are detected in coincidence, permitting us to record mass-selected photoelectron spectra. The threshold photoelectron spectrum of tropyl, corresponding to the 
\(X^{+1}A1’ ← X^2E_2”\) transition, reveals an ionisation energy of 6.23 ± 0.02 eV, in good agreement with Rydberg extrapolations, but slightly lower than the value derived from earlier photoelectron spectra. Several vibrations can be resolved and are reassigned to the C–C stretch mode \(ν_{16}^+\) and to a combination of \(ν_{16}^+\) with the ring breathing mode \(ν_2^+\). Above 10.55 eV dissociative photoionisation of tropyl is observed, leading to the formation of \(C_5H_5^+\) and \(C_2H_2\).
KW  - threshold photoelectron spectroscopy
KW  - gas phase
KW  - dissociative photoionisation
KW  - reactive intermediates
KW  - synchrotron radiation
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128652
VL  - 9
ER  -