Astronomy and Astrophysics – Astrophysics
Scientific paper
May 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008aas...212.0311n&link_type=abstract
American Astronomical Society, AAS Meeting #212, #3.11; Bulletin of the American Astronomical Society, Vol. 40, p.185
Astronomy and Astrophysics
Astrophysics
Scientific paper
Transitionsin singly-ionized and doubly-ionized iron-group elements give rise to prominent emission lines from a wide variety of astrophysical objects. Although the database of experimental oscillator strengths of Fe II has also been greatly extended by the FERRUM project, few experimental oscillator strengths are available in the region below 1600 Å, where many levels that give rise to emission lines at longer wavelengths have their dominant decays. The established way to measure accurate oscillator strengths for atomic lines combines the measurement of a lifetime of an upper energy level with a separate measurement of the branching fractions of all the lines emitted from that level. This technique relies on being able to observe all the spectral lines emitted by the upper level, which range down to Ly-α or below for many fluorescence lines.
We have developed techniques to measure branching fractions in the vacuum ultraviolet using our 10.7-m normal incidence grating spectrograph. For this we use phosphor image plates as replacements for the photographic plates previously used on this instrument. Image plates are sensitive to wavelengths from the X-ray region to 2200 Å, and have a linear intensity response with a dynamic range of at least 10000. We have recorded spectra of iron-neon hollow cathode and Penning discharges, using a deuterium standard lamp for radiometric calibration. We will present the first measurements of oscillator strengths using this technique. We are also investigating methods of radiometric calibration below 1150 Å using hollow cathode standard lamps. This will enable us to measure branching ratios down to 800 Å or below.
This work is partially funded by NASA under the inter-agency agreement W-10,255.
Nave Gillian
Sansonetti Craig J.
Szabo C. I.
No associations
LandOfFree
Atomic Oscillator Strengths In The Vacuum Ultraviolet does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Atomic Oscillator Strengths In The Vacuum Ultraviolet, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Atomic Oscillator Strengths In The Vacuum Ultraviolet will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1393843