urn:nasa:pds:context:instrument:lasp.mcpherson-vuvas 1.0 1.16.0.0 Product_Context 2023-08-28 1.0 Initial version. urn:nasa:pds:context:facility:laboratory.lasp instrument_to_facility McPherson VUVAS Spectrometer UV-VIS Seya-Namioka scanning-grating monochromator (McPherson, Inc. model 234/302) Vacuum UltraViolet Analytical Spectrophotometer, https://mcphersoninc.com/pdf/234302.pdf Reflectance measurements acquired at LASP were conducted using a customized f/4.5 modified Seya-Namioka scanning-grating monochromator (McPherson, Inc. model 234/302) Vacuum UltraViolet Analytical Spectrophotometer (VUVAS). Data for this work were acquired over the spectral range of far-UV into the visible (VIS) range (usable from 0.12 to 0.6 um; 120 to 600 nm) with a spectral sampling interval of 2 nm (4 nm spectral resolution). The incidence, emission, and phase angles were 30º, 0º, and 30º, respectively. The sample cup was 1.9 cm in diameter, and 0.6 cm deep. Each complete CU spectrum is a composite of four spectra obtained within the narrower, overlapping ranges of 120-240 nm, 210-320 nm, 290-400 nm, and 360-600 nm, under vacuum conditions. This strategy is required due to large variations in lamp brightness and instrument sensitivity, necessitating optimization of the photomultiplier tube (PMT) high voltage (HV) in each range. The lamp was either a 30 W deuterium (D2) lamp or a 100 W quartz-tungsten-halogen (QTH) lamp. A choice of two gratings with different ruling densities, spectral coverage, and dispersion was selected. The detector was a tilted scintillator (sodium salicylate) plate coupled to a reflective light pipe, feeding a photomultiplier tube (PMT) that was located outside the chamber.