Ultra High Resolution FTIR at the SLS IR beamline

Synchrotron radiation is normally associated with high brilliance x-rays, originating in the accelerated circular motion of the electrons. The Swiss Light Source (SLS) is one of a few synchrotrons that deliberately produce infrared light as well, by adding a small bending magnet along the way. This continuous-spectrum radiation extends far into the infrared, down to energies/frequencies of single millielectronvolts/hundreds of GHz. Compared to the conventional far-infrared (FIR) sources the synchrotron beam is approximately 100 times brighter while remaining a continuous beam for our practical purposes. This is unique combination which is difficult to come by.

When the beam enters the IR station it passes through a switching yard, where it can be channeled to different measurement setups. The most noticeable is the ultra-high-resolution Fourier transform infrared (UHR-FTIR) spectrometer (Bruker IFS125HR). In FTIR spectrometry the light is split into two arms, a fixed arm and a scanning one. The longer the scan, the higher the frequency resolution is. The UHR-FTIR has the longest commercially available scanning arm available, at 6.3 meters, giving it a spectral resolution of 30 MHz.

The combination of these two resources is unique in itself. Our measurement capabilities are further enhanced with the introduction of an optical-access dilution refrigerator with a base temperature of ~20mK and a 3D magnet.

Apart from the synchrotron beam we can also use the dilution refrigerator with our tunable pulsed laser for time resolved measurements and with our NKT  SuperK extreme source for visible to mid-infrared high power excitation.