Using the circularly polarized components of synchrotron radiation for circular dichroism measurements between 400 and 3500 Å

Abstract

The out of plane components of synchrotron radiation are circularly polarized to a high degree. This property offers the possibility to overcome the energy limitation of about 9 eV for circular dichroism (CD) and magnetic circular dichroism (MCD) measurements which is set by the optical components normally used to produce circularly polarized light. We report the first CD spectra which were taken using the circularly polarized components of synchrotron radiation. The light source was the Bonn 2.5 GeV synchrotron and a special monochromator constructed to monochromatize the off plane components of the radiation. Our experiments reveal several problems which make CD measurements very difficult. Some of these problems which we discuss in detail arise from the intrinsic properties of a synchrotron as compared to a storage ring but most are more general and have to be considered for further work on monochromators for the circularly polarized components of synchrotron radiation.