Transition probabilities for the 3s2 3p(2P0)-3s3p2(4P) intersystem lines of SI II

Abstract

view Abstract Citations (34) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Transition Probabilities for the 3 S 23p( 2P o)--3 s3p 2( 4P) Intersystem Lines of SI II Calamai, Anthony G. ; Smith, Peter L. ; Bergeson, S. D. Abstract Intensity ratios of lines of the spin-changing 'intersystem' multiplet of S II (4P yields 2P0) at 234 nm have been used to determine electron densities and temperatures in a variety of astrophysical environments. However, the accuracy of these diagnostic calculations have been limited by uncertainties associated with the available atomic data. We report the first laboratory measurement, using an ion-trapping technique, of the radiative lifetimes of the three metastable levels of the 3s3p2 4P term of Si II. Our results are 104 +/- 16, 406 +/- 33, and 811 +/- 77 micro-s for lifetimes of the J = 1/2, 5/2, and 3/2 levels, respectively. A-values were derived from our lifetimes by use of measured branching fractions. Our A-values, which differ from calculated values by 30 percent or more, should give better agreement between modeled and observed Si II line ratios. Publication: The Astrophysical Journal Pub Date: September 1993 DOI: 10.1086/187032 Bibcode: 1993ApJ...415L..59C Keywords: Atomic Energy Levels; Electron States; Line Spectra; Silicon; Transition Probabilities; Radiative Lifetime; Ultraviolet Spectra; Atomic and Molecular Physics; ATOMIC DATA full text sources ADS |