Ultrafast Photodissociation dynamics of Η5-CpMn(CO)3 (Cymantrene)
Full, Jürgen

HaupttitelUltrafast Photodissociation dynamics of Η5-CpMn(CO)3 (Cymantrene)
TitelzusatzTheory for Analysis and Control
TitelvarianteUltraschnelle Photodissoziationsdynamik von Η5-CpMn(CO)3 (Cymantren)
Zusatz zur TitelvarianteTheorie zur Analyse und Kontrolle
AutorFull, Jürgen
Geburtsort: Schweinfurt, Deutschland
GutachterProf. Dr. Jörn Manz
weitere GutachterProf. Dr. Ludger Wöste
Freie SchlagwörterPhotodissociation Dynamics, Quantum Chemistry, Analysis, Control
DDC540 Chemie und zugeordnete Wissenschaften
ZusammenfassungThis work deals with the quantum chemical and quantum dynamical description of the photodissociation of the transition metal complex cymantrene, CpMn(CO)3 (Cp = Η5-cyclopentadienyl), by means of ultrashort laser pulses (Femtochemistry). The goal is to understand recent pump-probe and control experiments performed by Wüste and coworkers (FB Physik, Freie Universität Berlin). The Mn-CO bond that dissociates first and ultrafast in experiment has been chosen as the reaction coordinate. Within the applied model, this coordinate lies in the plane of symmetry of the molecule, assuming CS symmetry and a staggered conformation of the Mn(CO)3 group with respect to the Cp ring. Quantum chemical ab initio potential energy curves for the lowest-lying neutral singlet and ionic doublet states are calculated along the reaction coordinate. The Complete Active Space Self-Consistent Field (CASSCF) method, followed by a Multireference Contracted Configuration Interaction (MR-CCI) treatment, is employed. CASSCF and MR-CCI transition dipole moments between neutral states are computed. The transition dipole moments coupling the neutral excited with the ionic states are approximated using the CI coefficients. In each symmetry, A' and A'', the two lowest excited singlet states, i.e. b1A' and c1A', and a1A'' and b1A'', avoid crossings in the Franck-Condon region. The kinetic couplings have been calculated numerically using the coefficients of the MR-CCI wave function and their influence on the photodissociation dynamics has been studied in both the adiabatic (kinetic coupling) and the diabatic (potential coupling) pictures, which are equivalent. Simulations of the pump-probe and control experiments are performed in the adiabatic representation. It is found that the nonadiabatic coupling between the a1A'' and the b1A'' states plays a crucial role in the interpretation of the pump-probe experiments, whereas the b1A' - c1A' coupling is negligible. A mechanism explaining the pump-probe experiments for the loss of the first CO ligand and another which decodes the optimal laser pulse optimizing the parent, CpMn(CO)3+, ion yield are proposed. The given analysis can also be extended to predictions about future optimization experiments yielding predominantly the first daughter ion, CpMn(CO)2+. In conclusion, this thesis presents the first ananlysis of the quantum mechanical details of an optimal control experiment yielding preferably the target ion, CpMn(CO)3+, while suppressing competing channels.
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Fachbereich/EinrichtungFB Biologie, Chemie, Pharmazie
Tag der Disputation22.10.2002
Erstellt am24.10.2002 - 00:00:00
Letzte Änderung19.02.2010 - 14:11:08
Alte Darwin URLhttp://www.diss.fu-berlin.de/2002/215/
Statische URLhttp://www.diss.fu-berlin.de/diss/receive/FUDISS_thesis_000000000754