Work Group Prof. Dr. F. Temps

State-Specific Unimolecular Dynamics of Vibrationally Highly Excited Molecules

Spectroscopy not only provides basic insight into the structures of molecules and molecular aggregates, it also reveals details on their dynamics that cannot easily be extracted by other methods. Following Christopher Columbus, who learned that there are two ways to India, by turning East or by turning West, the analysis of molecular spectra provides an equally important alternative route to obtaining molecular dynamics information compared to time-resolved measurements. 

In our work, a strong focus is on the quantum state-specific unimolecular dynamics of vibrationally highly excited molecules.

   

Quantum state-specific unimolecular dynamics by SEP

Stimulated Emission Pumping

Vibration-rotation quantum state resolved investigations of the unimolecular dissociative dynamics of highly vibrationally excited molecules at and above the dissociation limit performed in our group have led to a new level of understanding of unimolecular elementary chemical reactions. 

Highly detailed spectra are recorded using Stimulated Emission Pumping (SEP). For the prototypical radicals CH3O and HCO/DCO as almost ideal model systems, the relation between intramolecular vibrational redistribution (IVR) and "state-specific" or "statistical" molecular dynamics has rarely been elucidated in more detail. In the case of DCO, the unimolecular dissociation rates are predicted directly from the vibrational spectrum.

Important papers:

  • J. Wei, A. Tröllsch, C. M. Tesch, F. Temps, "Rotational State Dependent Mixings between Resonance States of Vibrationally Highly Excited DCO (X 2A')," J. Chem. Phys. 120, 10530 - 10542 (2004).
  • F. Renth, A. Tröllsch, F. Temps,  "Intramolecular Vibrational Energy Redistribution, Mode Specificity, and Non-Exponential Unimolecular Decay of Vibrationally Highly Excited States of DCO (X 2A')", J. Chem. Phys. 118, 659 - 668 (2003).
  • F. Temps, A. Troellsch, "Analysis of Highly Excited Vibrational Bound and Resonance States of DCO (X 2A) using an Effective Polyad Model Hamiltonian", Z. Phys. Chem. 215, 207 - 232 (2001).
  • C. Stöck, X. Li, H.-M. Keller, R. Schinke, F. Temps, "Unimolecular Dissociation Dynamics of Highly Vibrationally Excited DCO (X 2A'): I. Investigation of Dissociative Resonance States by Stimulated Emission Pumping Spectroscopy", J. Chem. Phys. 106, 5333 - 5358 (1997).
  • S. Dertinger, A. Geers, J. Kappert, F. Temps, J. W. Wiebrecht, "Rotation-Vibration State Resolved Unimolecular Dynamics of Highly Vibrationally Excited CH3O (X 2E): III. State Specific Dissociation Rates from Spectroscopic Line Profiles and Time Resolved Measurements", Faraday Discuss. Roy. Soc. 102, 31 - 52 (1995).