Optical cell with a temperature-control unit for a vacuum-ultraviolet circular dichroism spectrophotometer.

We constructed an assembled-type MgF2 cell that can function under a high vacuum (10(-4) Pa), and is capable of measuring the vacuum-ultraviolet circular dichroism (VUVCD) spectrum in a wavelength region down to 140 nm for aqueous solutions. Its path length can be adjusted by various spacers in the range from 1.3 to 50 microm. The temperature-control unit of the cell was also constructed with a Peltier thermoelectric element to keep the temperature of a sample within an accuracy of +/- 1 degrees C in the temperature range from -30 to 70 degrees C. The optical cell and the temperature-control unit were confirmed to have good performance by monitoring the VUVCD spectra of ammonium d-camphor-10-sulfonate and myoglobin aqueous solutions. This cell is available not only for VUVCD spectroscopy, but also for vacuum-ultraviolet absorption measurements.