Abstract
Wavelengths of absorption lines in the spectra of galaxies along the line-of-sight to distant quasars can be used to probe the variablility of the fine structure constant, α, at high redshifts, provided that the laboratory wavelengths are known to better than 6 parts in 108, corresponding to a radial velocity of ≈ 20 ms−1. For several lines of Si ii, C ii, Fe i, and Ni ii, previously published wavelengths are inadequate for this purpose. Improved wavelengths for these lines were derived by re-analyzing archival Fourier transform (FT) spectra of iron hollow cathode lamps (HCL) and a silicon carbide Penning discharge lamp, and with new spectra of nickel HCLs. By re-optimizing the energy levels of Fe i, the absolute uncertainty of 13 resonance lines has been reduced by over a factor of 2. A similar analysis for Si ii gives improved values for 45 lines with wavelength uncertainties over an order of magnitude smaller than previous measurements. Improved wavelengths for 8 lines of Ni ii were measured and Ritz wavelengths from optimized energy levels determined for an additional 3 lines at shorter wavelengths. Three lines of C ii near 135 nm were observed using FT spectroscopy and the wavelengths confirm previous measurements.
AgNPs@ZnO hybride nanoparticles infused thermoplastic polyester elastomer and their biocide effect
