The purpose of our study is to examine the molecular dynamics under synchrotron radiation with wavelength in far infrared region that has not yet been applied. Yamada and collaborators have succeeded in developing tabletop synchrotron light sources having 15 cm orbit radius for brilliant IR radiation named “MIRROCLE‐20”. The IR radiation from the entire electron orbit of exact circular is collected by circular mirror and quasi‐ellipsoidal mirror. The IR synchrotron light spectrum is centered at 10 &mgr;m wavelength and covers from few to 100 &mgr;m. The unique beam line is the monochromatic IR irradiation system, which was unable before due to the limited IR irradiation system. We are constructing the dispersive type monochrometer with gratings that reveals 1 to 1/2 &percent; bands monochromatic IR‐rays. Specimens are placed along 15 cm long focal plane with 30 chambers, where monochromatic IR‐rays are applied through slits with 1 mm width. We have a plan to detect chemical products due to the high flux IR irradiation with specific wavelength to the proteins in water. Molecular dynamics and enzymatic reaction under IR or FIR radiation have not yet been fully understood. Generally speaking, intramolecular vibration mode will be spread and finally transfer into thermal energy. Our research object is to clarify the relaxation process of the vibration energy and to control the chemical reactions through excitation of certain vibration mode of the target proteins with monochromatic IR rays. The structural change in the proteins will be detected by its chemical products as well as change in absorption and emission spectra. Sample in our mind is for instance Horseradish peroxidase (HRP). © 2004 American Institute of Physics