Quantendynamik photochemischer Reaktionen, die über konische Überschneidungen ablaufen

• Antragstellerinnen / Antragsteller: Professorin Dr. Leticia González; Professor Dr. Jörn Manz
• Mitantragsteller: Professor Dr. Omar Deeb; Professor Dr. Yehuda Haas; Professor Dr. Shmuel Zilberg
• Fachliche Zuordnung: Theoretische Chemie: Elektronenstruktur, Dynamik, Simulation
• Förderung: Förderung von 2005 bis 2015
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 13062693

• Erstellungsjahr: 2015

Zusammenfassung der Projektergebnisse

Since the discovery by L.S. Cederbaum, W. Domcke, H. Köppel & S. Shaik, Angew. Chem. 96 (1982) 221, it is commonly accepted that conical intersections (CIs) serve as funnels for ultrafast deactivation of electronic states, in the femtosecond time domain. Our trilateral project focuses on this field and adds further details and strategies for control of the quantum reaction dynamics (QRD) via CIs. Most importantly, we consider molecules which allow large amplitude motions (in particular torsions) in electronic excited states from one CI to another one, or to several other ones which are all equivalent by molecular symmetry (MS). For these types of systems, we discover, for the first time, effects of the MS on the QRD via the CIs. First of all, the QRD via two or more MS-equivalent CIs induces characteristic quantum mechanical interferences which depend on the irreducible representations (IREPs) of the non-adiabatic couplings that mediate the electronic transitions at the CIs. Second, these interferences are sensitive to the IREPs of the nuclear spin isomers (NSIs). This paves the way to new strategies for the preparation of NSIs, e.g. by shifting the CIs by means of strong (Stark) fields which affect the interference patterns. On the way, we could also discover various other fascinating effects e.g. a method that may allow determining CIs experimentally, effects of CIs not only on unimolecular but also on bimolecular reactions, and the Rydberg Center Shift effect of hydrogen transfer. Our results are based on the joint expertise of the partners from Israel, Palestine and Germany and recently (that means after a call of one of the project leaders) also from Austria, in complementary fields of Theoretical Chemistry: these include combinations of the methods, or if necessary also method developments, for the localization of CIs, ab initio quantum chemistry evaluations of the related electronic structures, QRD supplemented by ab initio nonadiabatic surface hopping molecular dynamics, and the theories of the MS and also laser control. The results should trigger investigations of the effects of MS on QRD via CIs and their control in many systems. Also very important: Our trilateral project provided a fruitful and pleasant cooperative frame that allowed the promotions of altogether seven PhD students from Israel, Palestine and Germany. Even though we headed for the effects which we could discover during this project in a systematic cooperative fashion, they may all be considered as surprising when looking back to the state-of-the-art at the start of our trilateral cooperation in 2005.

Projektbezogene Publikationen (Auswahl)

• Towards experimental determination of conical intersection properties: Twin State model and comparison with bound excited states, Phys. Chem. Chem. Phys. 13, 11872- 11877 (2011)
  S. Zilberg & Y. Haas
  
• H-abstraction is more efficient than cis-trans isomerizationm in (4-methlcyclohexylidene)floromethane. An ab initio molecular dynamics study, Phys. Chem. Chem. Phys. 14, 6241-6249 (2012)
  D. Kinzel, J. González-Vázquez & L. González
  
• Pyridinylidene-Phenoxide in Strong Electric Fields: Controlling Orientation, Conical Intersection, and Radiation-Less Decay, J. Phys. Chem. A 116, 11189-11198 (2012)
  S. Belz, S. Zilberg, M. Berg, T. Grohmann & M. Leibscher
  
• Stark Control of a Chiral Fluoroethylene Derivative, J. Phys. Chem. A 116, 2743-2749 (2012)
  D. Kinzel, P. Marquetand & L. González
  
• The photo-dissociation of the pyrrole- ammonia complex - the role of hydrogen bonding in Rydberg states photochemistry, Phys. Chem. Chem. Phys. 14, 8836- 8841, (2012)
  S. Zilberg, A. Kahan & Y. Haas
  
• Nuclear Spin Selective Torsional States: Implications of Molecular Symmetry, Z. Phys. Chem. 227, 1021-1048 (2013)
  S. Belz, O. Deeb, L. González, T. Grohmann, D. Kinzel, M. Leibscher, J. Manz, R. Obaid, M. Oppel, G. D. Xavier & S. Zilberg
  
• Discrimination of nuclear spin isomers exploiting the excited state dynamics of a quinodimethane derivative: J. Chem. Phys. 141, 164323, 1- 7 (2014)
  R. Obaid, D. Kinzel, M. Oppel & L. González
  
• Gas-phase electrophilic aromatic substitution mechanism with strong electrophiles explained by ab initio non-adiabatic dynamics, Phys. Chem. Chem. Phys. (Comm.) 16, 18686-18689 (2014)
  D. Kinzel, S. Zilberg & L. González
  
• A Molecular Symmetry Analysis of the Electronic States and Transition Dipole Moments for Molecules with Two Torsional Degrees of Freedom, J. Chem. Phys. 142, 064315, 1-9 (2015)
  R. Obaid & L. Leibscher
  
• Effects of Molecular Symmetry on Quantum Reaction Dynamics: Novel Aspects of Photoinduced Nonadiabatic Dynamics, J. Phys. Chem. A 119, 271-280 (2015)
  S. Al-Jabour & M. Leibscher