Infrared Science with Synchrotron Radiation

Synchrotron radiation is best known as a source of X-rays, but it is also a source for VUV to soft-Xrays photons. However, it was realised in the early 90’s that this source can also be exploited in the infrared energy domain. Even if in some frequency regions (roughly 30 microns and below) the total photon flux emitted by the synchrotron source remains inferior to that of a thermal source, the brightness of a synchrotron largely exceeds that of a laboratory thermal source. Enhancement as high as three orders of magnitude has been achieved in terms of brightness (or brilliance or spectral radiance). This is essentially the feature that is most exploited in infrared spectroscopy and microscopy. Besides brightness, other characteristics like time structure (few picoseconds duration) and well-defined polarization states are being also exploited. The main sources of infrared photons from storage rings are edge emission and bending magnet emission, and many recent infrared beamlines exploit both sources to double their experimental capacity.