The application-oriented research activities in the department of plasma diagnostics are centered on investigations for process monitoring and control, especially in molecular plasma processes. The focus is on the time and space-resolved qualitative and quantitative chemical analysis of molecular plasmas, both in the gas phase and on surfaces.
The department of plasma diagnostics works with the most modern methods and is constantly expanding the existing expertise as well as the spectrum of measurement devices and methods, especially laser-based plasma diagnostics. Spectroscopic questions in the spectral range from ultraviolet to terahertz are being addressed.
Plasma diagnostics enables the absolute measurement of energy and temperature distributions as well as densities of stable and transient species in the plasma by means of probe diagnostics, absorption spectroscopy, and optical emission spectroscopy allowing the determination of all relevant chemical processes.
Specially equipped laboratories for the diagnostics of practically simulated chemical plasma processes with state-of-the-art measuring equipment are available for the investigations.
The diagnostic methods are also suitable to be transported for external measurements.
The following methods are used for the quantitative determination of important parameters such as the species densities and their temperatures, the energy distribution of charged particles and for the characterization of all relevant chemical reaction paths:
- UVVIS: Pulsed dye laser
- Spectral range: 200 – 900 nm
- MIDIR: Diode laser, quantum cascade laser, interband cascade laser, lead-salt laser, and frequency comb laser system
- Spectral range: 300 nm to 20 µm
- CW and pulsed laser
- THz: quantum cascade laser and THz timedomain spectroscopy
- Spectral range: 0,05 – 5 THz
- Cavity ringdown spectroscopy (CRDS), cavity-enhanced absorption spectroscopy (CEAS), optical feedback CEAS (OF-CEAS), and cavity-enhanced attenuated total reflectance spectroscopy (CEATRS)
- FTIRspectroscopy from VIS to mid-IR
- Grating spectrograph with CCD and iCCD-cameras in the spectral range: 200 – 900 nm
- Langmuir probe for time-resolved determination of the electron energy distribution function, the average energy of electrons, plasma densities, the plasma potential, and the floating potential
- Quadrupole und EQP
- Synchronized ICCD and streak camera measurements in combination with fast electrical diagnostics (U, I, Q, E) for the analysis of breakdown processes in DBE and spark discharges
- Measurement of both individual breakdown events as well as the accumulation of repetitively generated plasmas for maximum sensitivity (time-correlated single photon counting, spectrally resolved)
- Fully electromagnetically shielded streak camera system for pulsed discharges with max. 2 ps time and 2 µm spatial resolution