ADVANCED EXPERIMENTAL-TECHNIQUES FOR MEASURING OSCILLATOR-STRENGTHS OF VACUUM-ULTRAVIOLET LINES

Advanced experimental techniques for measuring oscillator strengths of atomic and ionic transitions in the vacuum ultraviolet (VUV) are desc ribed. A VUV time-resolved laser-induced-fluorescence experiment for r adiative lifetime measurements on atoms and ions in a beam is operatio nal. Recent work on VUV transitions of Si I and B I is described. Thes e lifetimes provide the essential absolute normalization for convertin g relative oscillator strengths to absolute transition probabilities. Emission measurements of branching fractions at VUV and longer wavelen gths are proposed. A large echelle spectrograph equipped with a CCD de tector array will be used. This experiment will provide the sensitivit y, resolving power, and data handling capability required for extensiv e high quality emission branching fraction measurements. We further pr opose to use absorption measurements on hollow cathode discharges to d etermine relative absorption oscillator strengths. A demonstration of a new technique for absorption spectroscopy on glow discharges is repo rted. The new technique provides the sensitivity, dynamic range, and d ata handling capability required for extensive high quality absorption measurements. Relative absorption and emission oscillator strengths w ill be least-square adjusted using the bowtie method and normalized wi th accurate radiative lifetimes.