The first use of synchrotron radiation for vacuum ultraviolet circular dichroism measurements

Synchrotron radiation (SR) from modern electron storage rings is highly linearly polarized and more intense than conventional vacuum ultraviolet continuum sources. These unique properties make SR ideal for construction of a vacuum ultraviolet circular dichroism (CD) instrument. We report the first use of SR for CD measurements and describe the instrumental setup. These measurements were carried out in the wavelength range 1325-2050 Å on (+)-3-methylcyclopentanone at the Synchrotron Radiation Center of the University of Wisconsin-Madison. The signal to noise ratio, and therefore the resolution, was the best ever obtained for CD measurements in this wavelength range. This resulted in the observation of new structure and dramatic peak height changes in the CD spectrum. In addition, these measurements showed that the extension of CD measurements to higher energies is possible through the use of synchrotron radiation.