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High-accuracy Wavelengths and Energy Levels of Singly Ionized Nickel (Ni II) Measured using Fourier Transform Spectroscopy

Published

Author(s)

Christian Clear, Juliet Pickering, Gillian Nave, Peter Uylings, Ton Raassen

Abstract

High-resolution spectra of singly ionized nickel (Ni II) have been recorded using Fourier transform spectroscopy in the region 143–5555 nm (1800–70,000 cm−1) with continuous, nickel–helium hollow cathode discharge sources. An extensive analysis of identified Ni II lines resulted in the confirmation and revision of 283 previously reported energy levels, from the ground state up to the 3d8(ML)6s subconfigurations. Typical energy-level uncertainties are a few thousandths of a cm−1, representing at least an order-of-magnitude reduction in uncertainty with respect to previous measurements. Twenty-five new energy levels have now been established and are reported here for the first time. Eigenvector compositions of the energy levels have been calculated using the orthogonal operator method. In total, 159 even and 149 odd energy levels and 1424 classified line wavelengths of Ni II are reported and will enable more accurate and reliable analyses of Ni II in astrophysical spectra.
Citation
Astrophysical Journal Supplement Series
Volume
261

Keywords

atomic data, line: identification, methods: laboratory

Citation

Clear, C. , Pickering, J. , Nave, G. , Uylings, P. and Raassen, T. (2022), High-accuracy Wavelengths and Energy Levels of Singly Ionized Nickel (Ni II) Measured using Fourier Transform Spectroscopy, Astrophysical Journal Supplement Series, [online], https://doi.org/10.3847/1538-4365/ac7f9b, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=934520 (Accessed November 26, 2022)
Created August 4, 2022, Updated September 14, 2022