Shock tube measurements of Y I and Y II oscillator strengths

Abstract

Yttrium-silicon spectra have been photographed in the 3400- to 6200-Å region using a 3.4-m Ebert-type spectrograph. The light source was a helium-driven shock tube containing a mixture of powdered YSi 2 in an Ar carrier gas. A high-speed mechanical shutter and a Garton-type coaxial flashtube were used to record essentially simultaneous emission and absorption spectra for each shock. This procedure resulted in the testing for and removal of a number of systematic errors during reduction of the data, yielding relative oscillator strengths for 255 Y I lines and 90 Y II lines. These relative oscillator strengths have been placed on an absolute scale using the published gf-values of Hannaford et al. and the 3906-Å line of Si I. A comparison of these results with those of previous workers shows general agreement, although significant differences are seen in several cases.