Lifetimes and Oscillator Strengths for Ultraviolet Transitions in Singly Ionized Copper

High-quality oscillator strengths are needed to convert the amount of interstellar absorption into an accurate abundance from data acquired with the Hubble Space Telescope and the Far Ultraviolet Spectroscopic Explorer . In order to help clarify the appropriate values to use for ultraviolet transitions in Cu ii , we report lifetimes from our beam-foil experiments. The Cu ii results for the 1358.773 Å line (3 d 10 1 S 0 –3 d 9 4 p 1 P o 1 ) provide further evidence for a short lifetime for the upper level of interest. Additional results for transitions that can repopulate this upper level indicate that the data are not affected by cascades. Our measured lifetime, the most precisely determined to date, is in excellent agreement with the most recent experimental results and is consistent with theoretical values. When combined with the theoretical branching fractions of Donnelly et al. and Dong & Fritzsche, we obtain a value of 0.273 ± 0.028 for the oscillator strength, which is in very good agreement with the theoretical results of Donnelly et al. and the most recent recommended value given by Morton.