Accurate laboratory wavelengths of some ultraviolet lines of Cr, Zn and Nirelevant to time variations of the fine structure constant

The quality of astronomical spectroscopic data now available is so high tha t interpretation and analysis are often limited by the uncertainties of the laboratory data base. In particular, the limit with which space-time varia tions in the fine structure constant alpha can be constrained using quasar spectra depends on the availability of more accurate laboratory rest wavele ngths. We recently measured some transitions in magnesium by high-resolutio n Fourier transform spectroscopy for this purpose, and we now report measur ements on some ultraviolet resonance lines of Zn II (2062 and 2026 Angstrom ), Cr II (2066, 2062 and 2056 Angstrom) and Ni II (1751, 1741, 1709 and 170 3 Angstrom). Apart from the last line, which is very weak, the uncertainty of these measurements is 0.002 cm(-1) (0.08 m Angstrom) for the lines aroun d 2000 Angstrom and 0.004 cm(-1) (0.12 m Angstrom) for the lines around 170 0 Angstrom.