FIR spectra were either recorded on a home-built setup, using a Bruker Vertex 70v Fourier transform infrared spectrometer that is coupled to an Oxford Instruments 15T (17T) solenoid magnet or at the High Field Magnet Laboratory (HFML) in Nijmegen (Netherlands). Here, a Bruker Vertex 80v spectrometer is coupled to a 33 T Bitter magnet. In both cases, silicon bolometers were used as detectors. In the first case, an external Infrared Laboratories bolometer was used; in the second case, a home-built internal bolometer was used. The samples were prepared in both cases as 8 mm pellets. Here, a mixture of 20 weight percent of sample inside finely ground eicosane was used.