This award supports a program of continued studies using the vacuum ultraviolet high-resolution spectrometer facility (HRSF) at the SURF II storage ring of the National Institute for Standards and Technology (NIST). After more than two years of intensive work under the previous grant, by the University of the District of Columbia's faculty and students and NIST personnel, the spectrometer facility is ready for its intended purpose of measuring useful EUV cross-sections of interest in Aeronomy: intensity is up by a factor of 120 over two years ago and the resolution has improved from 0.014 A to , 0.009 A. Experiments will be performed to measure absolute absorption in N2. The high resolution measurements near 83.4 nm will provide new information needed to accurately model the interaction of solar EUV radiation with the terrestrial upper atmosphere.
