Far-infrared spectroscopy on solids under high pressure by infrared synchrotron radiation

SPring-8, which is the third generation X-ray light source and has the largest storage ring among synchrotron radiation facilities in the world has been proved also to provide two order of magnitude higher infrared photon fluxes than a conventional globar lamp. We completed the construction of the beamline, BL43IR which is dedicated only to infrared spectroscopy and developed a far-infrared spectroscopic system under high pressure up to 15 GPa by using a diamond anvil cell combined with IR-microscopy. In this paper, we report the recent results of study on the change in the electronic structure of transition metal compounds due to a pressure-induced electronic phase transition as the example of our recent progress in the application of infrared synchrotron radiation to solid state physics.