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IUPAC Prize for Young Chemists - 2008
Honorable Mention


Stefan Knippenberg receives one of four Honorable Mention awards associated with the IUPAC Prize for Young Chemists, for his Ph.D. thesis work entitled entitled "Green’s function and Dyson orbital studies of the electronic structure of cage compounds and flexible molecules."

Current address (at the time of application)

Institut für Physikalische und Theoretische Chemie
Johann Wolfgang Goethe Universität Frankfurt
Frankfurt/Main, Germany

E-mail: [email protected]

Academic degrees

  • Ph.D., Hasselt University (Belgium), October 2007, Physical Chemistry – Chemical Physics
  • Master, Catholic University of Leuven (Belgium), July 2003, High Energy Physics
  • Bachelor: Hasselt University (Belgium), July 2001, Physics

Ph.D. Thesis

Title Green’s function and Dyson orbital studies of the electronic structure of cage compounds and flexible molecules: a confrontation of many-body quantum mechanics with electron momentum, photo electron and Penning ionization electron spectroscopies

Adviser Professor M. S. Deleuze (Department SBG, Hasselt University, Belgium)

Thesis Committee Prof. E. Nauwelaerts (Departement Wiskunde Natuurkunde-Informatica, Hasselt University); Prof.. J.-P. François (Departement Scheikunde-Biologie-Geologie, Hasselt University); Prof. C. Vanderzande (Departement Wiskunde-Natuurkunde Informatica, Hasselt University); Prof. A. Ceulemans (Afdeling Kwantumchemie en Fysicochemie, Catholic University of Leuven); Prof. P. Lievens (Afdeling Vaste-Stoffysica en Magnetisme, Catholic University of Leuven); Prof. P. Geerlings (Eenheid Algemene Chemie, Free University of Brussels); Prof. D. Van Neck (Centrum voor Moleculaire Modellering, Ghent University); Prof. J. H. D. Eland (Chemistry Department, Oxford University, United Kingdom); Prof. W. H. E. Schwarz (Theoretische Chemie, Siegen University, Germany)


Orbitals are ubiquitous in the quantum theory of matter. It is well known that, at the molecular level, motions of electrons can only be statistically described through one-electron waves – the orbitals. For many-electron systems, the consistency of the orbital formalism can only be assessed by comparing various predictions drawn from quantum mechanics with a set of experimental observations. In this context, Electron Momentum Spectroscopy has triggered a revolution in our perception of the electronic structure of matter. In contrast with most structural analysis techniques which can only deliver direct information on the total electron densities, this technique indeed affords direct measurements in momentum space of the electron density associated to a single ionization channel (i.e. an orbital in a one-electron picture), through detailed investigations of the angular dependence of electron impact ionization intensities. The obtained momentum distributions (MDs) are equivalent to structure factors derived as the square of the Fourier Transform of suited orbitals, namely Dyson orbitals, defined as partial overlaps between the initial (neutral) and final (cationic) wavefunctions in an ionization process. EMS enables us therefore to directly assess the intimate relationships that prevail between the configuration and momentum spaces for specific ionization channels related to well defined electron energy levels.....[full text; pdf file - 430KB]


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