Far infrared experiments

Far-infrared spectroscopy is used for measuring low-energy optical excitations in high magnetic fields, such as various electron magnetic resonances (ESR, cyclotron resonance, antiferromagnetic resonance).
Currently, only the transmission measurement in the Faraday configuration is available; Voight configuration and reflectivity are under development. The signal is detected using a sample probe which contains a He(l) cooled Si bolometer.

We offer two modes of experimentation:

  1. Fixed frequency, sweeping field, using an optically pumped molecular laser.
    Source: Various narrow laser lines (~40-1500 µm, 0.8-30 meV), with powers up to 1mW. The radiation is guided to the sample using an oversized waveguide.
  2. Fixed field, broad-band spectroscopy using a Bruker ifs113v FT spectrometer.
    Source: Mercury arc lamp, providing nW power of FIR radiation. A quasi-optical telescope is used to transport the radiation down to the sample tube, where it is guided through the sample and onto the detector. Spectral range is 12cm-700cm (1.5‑90meV). Depending on the wavelength, absorption as small as 0.5% can be detected.

Sample requirements

Optimal sample size is 5x5x1 - 8x8x3 mm3. Specific sample holders can always be made, up to 15mm (largest dimension).
Samples and substrates should be transparent in the energy range of interest.


Linear polarizers and long-pass optical filters (<40cm-1, <200cm-1) are available.