1,039 research outputs found
Interferometric measurement of resonance transition wavelengths in C IV, Si IV, Al III, Al II, and Si II
We have made the first interferomeric measurements of the wavelengths of the
important ultraviolet diagnostic lines in the spectra \ion{C}{4} near 155 nm
and \ion{Si}{4} near 139 nm with a vacuum ultraviolet Fourier transform
spectrometer and high-current discharge sources. The wavelength uncertainties
were reduced by one order of magnitude for the \ion{C}{4} lines and by two
orders of magnitude for the \ion{Si}{4} lines. Our measurements also provide
accurate wavelengths for resonance transitions in \ion{Al}{3}, \ion{Al}{2}, and
\ion{Si}{2}.Comment: 6 pages, 2 figures, 1 tabl
Weak line water vapor spectrum in the 13 200–15 000 cm−1 region
New Fourier transform spectra of water vapor are presented in the range 6500–16 400 cm−1 obtained using pathlengths of up to 800 m and long integration times. These spectra have a significantly higher signal-to-noise than previous measurements in this wavenumber range. Wavenumbers, absolute intensities and self-broadening coefficients, all with associated uncertainties, are presented for 3604 lines in the region 13 200–15 000 cm−1. Analysis of these lines using variational linelists, along with other unassigned lines from previous studies, has been conducted. This leads to 952 new line assignments to transitions involving 35 different vibrational states of H216O. A smaller number of lines are assigned to H218O and H217O
Wavelengths of the 3d6(5D)4s a6D - 3d6(5D)4p y6P Multiplet of Fe II (UV 8)
We investigate the wavenumber scale of Fe I and Fe II lines using new spectra
recorded with Fourier transform spectroscopy and using a re-analysis of
archival spectra. We find that standards in Ar II, Mg I, Mg II and Ge I give a
consistent wavenumber calibration. We use the recalibrated spectra to derive
accurate wavelengths for the a6D-y6P multiplet of Fe II (UV 8) using both
directly measured lines and Ritz wavelengths. Lines from this multiplet are
important for astronomical tests of the invariance of the fine structure
constant on a cosmological time scale. We recommend a wavelength of 1608.45081
{\AA} with a one standard deviation uncertainty of 0.00007 {\AA} for the
a6D9/2-y6P7/2 transition.Comment: 29 pages, 7 figures, 8 tables. Accepted for publication in J. Opt.
Soc. Am
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