Experiment nr. 20

Fourier-Transform-Infrared-Spectroscopy on Solids

Supervisor: Dr. Volker Riede

The Fourier-Transform Spectroscopy is a fundamental spectroscopic method. The measurement method of this experiment is introduced with the help of investigations in the infrared spectral region. The most important component of the infrared spectrometer is the Michelson Interferometer.
Using specific measurements the mathematical basics and the measuring method of the Fourier-Transform-Infrared (FTIR) Spectroscopy are investigated, e.g. the connection between the intensity spectrum and the interferogram as well as the dependence of the resolving power on the optical path.
With the aid of these findings the local lattice modes of oxygen in Si:O and of nitrogen in GaNAs are investigated and calculated using a simple theoretical model.

As an additional task the reflectivity of a GaNAs sample is to be determined by experiment and by calculations.

The FTIR spectrometer IFS 48 used in this experiment is a perpetual loan of the Bruker Optik GmbH.