CRC 1316 Transient Atmospheric Plasmas: From Plasmas to Liquids To Solids

A1 A2 A3 A4 A5 A6 A7 A8 A9 B1 B2 B4 B5 B7 B8 B11 B12 B13 B14 B15 INF MGK PR

A2: Ro-vibrational distribution measurement in transient discharges by coherent anti-Stokes Raman scattering

Principal Investigators: U. Czarnetzki, D. Luggenhölscher


Czarnetzki, Uwe
(Principal Investigator)

Luggenhölscher, Dirk
(Principal Investigator)

Busch, Christian



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.



  • Jan Kuhfeld, PhD thesis - 12/2022
    Ro-vibrational distribution measurement in transient discharges by coherent anti-Stokes Raman scattering
  • Jutta Püttmann, Bachelor thesis - 09/2019
    Electric Field Measurementsvia EFISH in a CARS Setup

Further reading

  • Sensitive Electric Field Measurement by Fluorescence-Dip Spectroscopy of Rydberg States of Atomic Hydrogen
    U. Czarnetzki, D. Luggenhölscher and H.F. Döbele,
    Physical Review Letters 81 (1998) 4592
  • Electric field measurement in an atmospheric or higher pressure gas by coherent Raman scattering of nitrogen
    T. Ito, K. Kobayashi, S. Müller, D. Luggenhölscher, U. Czarnetzki, and S. Hamaguchi
    J. Phys. D: Appl. Phys. 42 (2009) 092003