The Cu II Spectrum

Abstract

New wavelength measurements in the vacuum ultraviolet (VUV), ultraviolet and visible spectral regions have been combined with available literature data to refine and extend the description of the spectrum of singly ionized copper (Cu II). In the VUV region, we measured 401 lines using a concave grating spectrograph and photographic plates. In the UV and visible regions, we measured 276 lines using a Fourier-transform spectrometer. These new measurements were combined with previously unpublished data from the thesis of Ross, with accurate VUV grating measurements of Kaufman and Ward, and with less accurate older measurements of Shenstone to construct a comprehensive list of ≈2440 observed lines, from which we derived a revised set of 379 optimized energy levels, complemented with 89 additional levels obtained using series formulas. Among the 379 experimental levels, 29 are new. Intensities of all lines observed in different experiments have been reduced to the same uniform scale by using newly calculated transition probabilities (A-values). We combined our calculations with published measured and calculated A-values to provide a set of 555 critically evaluated transition probabilities with estimated uncertainties, 162 of which are less than 20%.

Development of NIST Atomic Databases and Online Tools

“…Sometimes it requires making new measurements and/or theoretical calculations. A typical example is the recent critical compilation of Cu II spectral data [ 11 ], which took several years to complete. As a result, most of the data sets in ASD are missing the latest new determinations.…”

A New Test of Copper and Zinc Abundances in Late-type Stars Using Ultraviolet Cu ii and Zn ii Lines*

“…Roederer & Lawler (2012) evaluated the quality of oscillator strengths available for seven Cu ii lines. Kramida et al (2017a) have released an updated critical compilation of Cu ii oscillator strengths, which are in-cluded in the most recent NIST ASD update. The two sets of oscillator strengths agree to within their stated uncertainties, and we simply adopt the values recommended by Roederer & Lawler. Four of these lines, listed in Table 4, are detected in most of our spectra.…”

Response to Referee #1

“…The ions and free electrons are not observed in the mass spectrometer because their life time is far too short to reach the detector. For example, the transition probability of the ionization state represented by the copper emission line at 775.40 nm is 9 × 10 6 /s (Kramida et al, 2017). Thus, the mean lifetime of this ion is 1/(9 × 10 6 ) ≈ 0.1s.…”