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

Principal Investigators: U. Czarnetzki, D. Luggenhölscher

Team


Czarnetzki, Uwe
(Principal Investigator)

Luggenhölscher, Dirk
(Principal Investigator)

Kuhfeld, Jan
(PhD)

Du, Yanjun
(PostDoc)

Description

ImageRo-vibrational excitation of small molecules by electron collision and collisional excitation transfer between molecules is at the bottom of all chemical processes in the focus of the research collaboration. 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 timescales stretch from ns for the electron interaction to ms or even ms for collision transfer and chemical reactions. Related questions involve the excitation mechanism by electrons, including interaction of electrons with excited states by superelastic collisions, excitation transfer within one species, e.g. CO2 with CO2, excitation transfer between different molecules, e.g. N2 with CO2, and the final degree of dissociation, e.g. forming CO. The ro-vibrational population distribution of all these molecules will be measured by coherent anti-Stokes Raman scattering (CARS) with high selectivity and temporal and spatial resolution. The optical set-up will be optimised for the simultaneous measurement of entire population distributions and detection of two molecular species in parallel. Application will be to a number of discharges used in the collaboration. Further, two ns-pulsed atmospheric pressure jets with crossed beams will be set-up which will allow addressing the above questions under controlled and well characterised conditions.

Publications

  • Vibrational CARS measurements in a near-atmospheric pressure plasma jet in nitrogen: I. Measurement procedure and results
    J. Kuhfeld, N. Lepikhin, D. Luggenhölscher, U. Czarnetzki
    J. Phys. D: Appl. Phys. 54 305204 (2021)
  • Nanosecond resolved ro-vibrational CO2 excitation measurement
    Y. Du, Ts. V. Tsankov, D. Luggenhölscher, U. Czarnetzki
    J. Phys. D: Appl. Phys. 54 34LT02 (2021)

Thesis

  • Jan Kuhfeld
    Ro-vibrational distribution measurement in transient discharges by coherent anti-Stokes Raman scattering (PhD thesis) - 04/2021
  • Jutta Püttmann
    Electric Field Measurementsvia EFISH in a CARS Setup (BA) - 09/2019

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

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