Project Details
Projekt
Ro-vibrational distribution measurement in transient discharges by coherent anti-Stokes Raman scattering (A02)
Subject Area
Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
Term
since 2018
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 327886311
Vibrational (and rotational) excited molecules play a key role in plasma chemistry since due to their high internal energy they strongly affect the chemical processes. An open question is the role of excited states in catalytic reactions. The excitation of the molecules occurs by collisions with energetic electrons present in the plasma and by excitation transfer from already excited molecules. The detailed physical mechanisms and rate constants are often not known or have not been validated in experiments. Further, simulations are generally very involving, in particular in connection with highly transient discharges at atmospheric pressures, where time scales stretch from ps for the electron interaction to μs or even ms for collision transfer and chemical reactions. Therefore, this project aims at the measurement of the ro-vibrational excitation of CO2 and N2 by coherent anti-Stokes Raman scattering (CARS). In addition to the experimental setup also a new analysis procedure has been developed that allows addressing non-equilibrium distribution functions. Further, an analytical model allows ab-initio prediction of the population distributions with electric field data and current measurements taken from project A1. Independent control on plasma density and electric field in ns-discharges is demonstrated. This allows an optimized coupling of almost the entire energy of the electrons in the plasma bulk into vibrational excitation.
DFG Programme
Collaborative Research Centres
Applicant Institution
Ruhr-Universität Bochum
Project Heads
Professor Dr. Uwe Czarnetzki; Dr. Dirk Luggenhölscher
