NIST VUV metrology programs to support space-based research

Vacuum ultraviolet (VUV) radiation, spanning the electromagnetic spectrum from about 2 nm (620 eV) to 200 nm (6.2 eV) has long been important in astronomy, solar physics, and Earth observing systems, among other applications. The National Institute of Standards and Technology (NIST) has several programs to serve the VUV user community, from the Synchrotron Ultraviolet Radiation Facility (SURF III) - a standard of irradiance from 2 to 400 nm - to measurement and calibration services for mirrors, photodiodes, and filters. We have recently reduced the uncertainty of our extreme ultraviolet (EUV) detector calibrations by implementing an absolute cryogenic radiometer on one of the SURF beamlines, and have effected several improvements to the EUV detector calibration beamline at SURF. We continue to investigate wide-bandgap semiconductors for use as solar-blind detector technologies, and have recently obtained quantum efficiency and uniformity data from 1 cm2 active area GaN and SiC photodiodes.