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Wavelengths of Fe ii lines for studies of time variation of the fine-structure constant




Ritz wavelengths of 27 spectral lines of Fe ii have been obtained from energy levels derived from Fourier transform spectra. The lines selected are observable in absorption spectra from quasi-stellar objects and are important for astronomical tests of the invariance of the fine-structure constant on a cosmological time-scale. By comparing the wavelength calibration in this paper with that of previously published measurements, wavelengths for 21 lines of Mg i, Mg ii, Cr ii, Ti ii, Mn ii, Ni ii and Zn ii have been placed on a scale consistent with the Fe ii Ritz values.