The N(D-2 degrees-S-4 degrees) 520 nm forbidden doublet in the nightglow: An experimental test of the theoretical intensity ratio - art. no. L12106

摘要

[ 1] The ratio of intensities of the optically forbidden lines N(D-2 degrees-S-4 degrees) 519.8, 520.0 nm has been measured with high precision in the nightglow in repeated observations made with the High Resolution Echelle Spectrophotometer ( HIRES) and Echellette Spectrograph and Imager ( ESI) on the Keck I and Keck II telescopes, respectively, at the W. M. Keck Observatory on Mauna Kea, Hawaii. The observed intensity ratio, I( 519.8 nm)/I(520.0 nm), is seen to vary little over the bulk of any particular night, with a value of 1.759 +/- 0.014 determined over all observations. Among theoretical predictions of the ratio, this agrees best with a value of 1.788 determined from the ratio of products of recent Breit-Pauli calculation-derived spontaneous emission coefficients ( Froese Fischer and Tachiev, 2004) and statistical weights of the fine structure levels of the D-2 degrees term, under the assumption that these levels' populations are thermalized by rapid mixing through collisions with N-2.