The Spectrum of Thorium from 250 nm to 5500 nm: Ritz Wavelengths and Optimized Energy Levels

Published

February 6, 2014

Author(s)

Stephen L. Redman, Gillian Nave, Craig J. Sansonetti

Abstract

We have made precise new observations of the spectrum emitted by a thorium-argon hollow cathode lamp in the region 350 nm to 1175 nm using a high-resolution Fourier transform spectrometer. Our measurements are combined with results from seven previously published thorium line lists (Giacchetti et al. 1974; Zalubas & Corliss 1974; Zalubas 1976; Palmer & Engleman 1983; Engleman et al. 2003; Lovis & Pepe 2007; Kerber et al. 2008) to re-optimize the energy levels of neutral, singly-, and doubly-ionized thorium (Th I, Th II, and Th III). Using the optimized level values, we calculate accurate Ritz wavelengths for 19646 thorium lines between 250 nm and 5 500 nm (40000 cm−1 to 1800 cm−1). We have also found 102 new thorium energy levels. A systematic analysis of previous measurements in light of our new results allows us to identify and propose corrections for systematic errors in Palmer & Engleman (1983) and typographical errors and incorrect classifications in Kerber et al. (2008). We also found a large scatter in the thorium line list of Lovis & Pepe (2007). We anticipate that our Ritz wavelengths will lead to improved measurement accuracy for current and future spectrographs that make use of thorium-argon or thorium-neon lamps as calibration standards.

Citation

Astrophysical Journal Supplement Series

Pub Type

Journals

Download Paper

https://doi.org/10.1088/0067-0049/211/1/4

Keywords

atomic spectra, energy levels, near infrared, optical, Ritz wavelengths, thorium, wavelengths

Citation

Redman, S. , Nave, G. and Sansonetti, C. (2014), The Spectrum of Thorium from 250 nm to 5500 nm: Ritz Wavelengths and Optimized Energy Levels, Astrophysical Journal Supplement Series, [online], https://doi.org/10.1088/0067-0049/211/1/4 (Accessed October 9, 2025)