Berlin 2001 – scientific programme
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A: Atomphysik
A 17: Posters Friday (Spectroscopy)
A 17.4: Poster
Friday, April 6, 2001, 12:30–15:00, AT3
Accurate new measurements of branching ratios and atomic transition probabilities of some Fe II transitions — •Juliet C. Pickering — Imperial College, Prince Consort Rd, London SW7 2BZ, UK
At Imperial College (IC) the Fourier Transform (FT) Spectroscopy group continues to study spectra to give large improvements to the atomic data base for astrophysics; accurate line transition probabilities are needed for elemental abundance determinations in astrophysical objects. The IC VUV FT spectrometer was used to measure the relative intensities of about 100 emission lines of Fe II between 160 and 350 nm from 7 levels. A Penning discharge lamp was used as light source. The measured line relative intensities gave the line branching fractions, which when combined with accurate experimental radiative lifetime measurements measured at Lund University yielded absolute transition probabilities. Typical uncertainties in the transition probabilies are less than 12% for strong lines and better than 20% for the majority of weaker lines. We compare our measurements with theoretical calculations. This work represents the first complete measurement of f-values for transitions from the four 3d6(a3F)4p levels: y4F7/2, x4D7/2, y4G9/2, and y4G7/2, and new f-values for transitions from the three 3d6(a3F)4p y6P3/2, 5/2, 7/2 levels.