Abstract

A number of transitions between levels of the ground (6p3) configuration of Bi₂O₉ are a mixture of electric-quadrupole and magnetic-dipole radiation. The degree of mixture is described by the ratio of the radial parts of the transition probability integrals E and M. The 648 nm transition includes 12 mixed magnetic-dipoleelectric-quadrupole components plus a number of weaker electric quadrupole (F = 2) components. These components comprise six groups of two or three closely spaced components each. This suggested the use of high-resolution grating spectrometer which is able to separate the groups, as a cross-disperser for a Fabry–Perot interferometer. Interferograms were recorded photographically on 103a-F spectroscopic plates with exposures of up to 12 h. A microdensitometer was then used to determine densities, which were converted to intensities by means of our plate calibration curves. We observed all 14 components already described in the literature plus two new F = −2 components. The ratio of electric quadrupole to total line strength was determined from the four electric quadrupole component intensities compared to total intensities and inversely weighted by the known angular portions of the transition probability integrals. Our results show an electric quadrupole contribution of 30 5% to this mixed transition, compared to previously reported values of about 20%.

© 1990 Optical Society of America