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 C iv near 155 nm and Si iv near 139 nm with a vacuum ultraviolet Fourier transform spectrometer and high-current discharge sources. The wavelength uncertainties were reduced by 1 order of magnitude for the C iv lines and by 2 orders of magnitude for the Si iv lines. Our measurements also provide accurate wavelengths for resonance transitions in Al iii, Al ii, and Si ii.