Intensity Calibration of Normal Incidence Monochromator by the Double Monochromator Method

Abstract

The double monochromator method is applied to the calibration of the sensitivity of a monochromator in the vacuum ultraviolet region. A pre-monochromator for delivering monochromatic light and a main monochromator to be calibrated are connected in tandem as a double monochromator. The detector attached to the main monochromator is a photomultiplier coated with sodium salicylate. The monochromatic light flux from the pre-monochromator is measured by absolute detectors such as a photodiode calibrated in the region 1200 to 2300 Å. The pre-monochromator is rotated about the exit principal ray through 90 deg. so as to compensate for the polarization effect of the monochromatic light. The molecular branching ratio method is also applied to the calibration and the results are compared with the double monochromator method.