Measurement of the Complex Index of Refraction for Uranium Dioxide in the Extreme Ultraviolet

Utah State University

The reflectance and transmittance in the extreme ultraviolet (XUV) for a diode sputtered with a uranium dioxide film (approximately 20 nanometers thick) were measured. The reflectance data for the coated side has been fit to the Parratt model in order to determine the thickness of the film. Fitting the transmission data to a simple model and combining this with the thickness calculation from the reflectance data yielded an estimate for the complex part of the index of refraction for uranium dioxide in the XUV region at every tenth of a nanometer in wavelength. The values will be further refined by a more robust analysis of both the reflectance and transmission data which the BYU XUV research group is currently undergoing. These values provide researchers with information for modeling, design and fabrication of optical systems in the extreme ultraviolet.