Prof. Feile – Research
The main method being used in the working group are Raman- and Brillouin-spectroscopy. Both are optical spectral techniques with different resolution. The frequency shifting of the incident light while interacting with the excitations of different systems in condensed matter.
- Raman spectroscopy works for the frequency intervall from 10cm-1 to 5000cm-1 which corresponds to energies from 0.001eV to 0.6eV. That covers the regime of molceular and lattice vibrations.
- For smaller frequencies of 500 MHz to 30 GHz, i.e., energies from 2μeV to 120μeV, Brillouin spectroscopy is used. For instance it is possible to study the propagation of high frequency accustic waves (hypersound). For even lower excitation frequencies one can use ultrasonic or laserreflectometric methods.
Fields of activity and methods
The group is equipped with a double-grating monochromator for the Raman spectroscopy and a modern tandem Fabry Perot interferometer for Brillouin investigations. These devices are supplemented with an Ar-ion laser as well as a NdYAG laser as sources of light, various cryostats, 'closed cycle'-devices for taking the temperature range from approx. 2,5 to 300 K and a diamond high pressure cell for investigations under the pressure of up to approx. 30 GPa.