Critically Evaluated Spectral Data for Neutral Carbon (${\rm{C}}\,{\rm{I}}$)

Abstract

ABSRACT In this critical compilation, all known to us experimental data on the spectrum of neutral carbon were methodically evaluated and supplemented by parametric calculations with Cowan's code. The sources of experimental data vary from laboratory to astrophysical objects and employ different instrumentation from classical grating and Fourier transform spectrometers to precise laser spectroscopy setups and various other modern techniques. This comprehensive evaluation provides accurate atomic data on energy levels and wavelengths (observed and Ritz) with their estimated uncertainties, as well as a uniform description of observed line intensities. In total, 412 energy levels were optimized with the help of selected 1221 best observed lines participating in 1365 transitions in the wavelength region 750 Å to 609.14 µm. In addition, 737 possibly observable transitions are predicted. Critically evaluated transition probabilities for 1616 lines are provided, of which 241 are new. With the accurate energy levels obtained,combined with additional observed data on high Rydberg states, the ionization limit was determined to be 90 820.348(9) cm −1 or 11.2602880(11) eV in fair agreement with the previously recommended value, but more accurate.

Revision of the ionization energy of neutral carbon

“…The fit was performed on a data set that consisted of the measured Rydberg state transition energies added to the intermediate state energy of 60 393.1693(14) cm −1 [1]. The fit with a 4-term modified Ritz formula (see equation (1b) in [12]) yields 90 883.743(9) cm −1 (with levels n=53, 54, and 55 excluded) for the interval between the atomic ground state and the ionic 2 P°3 /2 excited state, where the uncertainty includes the following contributions: the standard deviation of the fit with the given values of energies, 0.005 cm −1 , the standard deviation (0.006 cm −1 ) of 500 fits (of the same Ritz formula) with the level energies randomly varied around their nominal values with normal distributions of a width corresponding to their measurement uncertainties, and a systematic uncertainty in the measured n6 energies, estimated to be 0.003 cm −1 .…”

“…These properties of the species involved include transition energies of both allowed and forbidden transitions, transition probabilities, dissociation energies of molecules, and ionization energies of the neutral and ionic species. A detailed review of the scope and importance of accurate photophysical data on carbon can be found in a recent paper by two of us [1].…”

Carbon-rich (DQ) white dwarfs in the Sloan Digital Sky Survey

“…In the National Institute for Standards and Technology (NIST,Kramida et al 2018) database 3 are only two lines in this range with log g f values published, none with class A quality. The sources areHaris & Kramida (2017) andLuo & Pradhan (1989). In a literature search we found only very few data, 3 https://www.nist.gov/pml/atomic-spectra-database Analysis results for the complete DQ sample.Top panel: log g as a function of T eff for DQ (black crosses), wDQ (red xses), and hDQ (blue squares).…”

Atomic and Molecular Physics. A Primer. By Luciano Colombo. IOP Science, 2019. Ebook, pp. 219. ISBN 978-0-7503-2260-7.

“…It is stated that since the difference in energy between the 2s and 2p states is small, the excited configuration 2s) 1 (2p3 is most likely to be found at room temperature rather than the (2s) 2 (2p) 2 one. Indeed, experimental results (Haris & Kramida, 2017) show that the difference in energy between the lowest-energy terms of these two configurations ( 3 P for the ground state and 5 S for the excited configuration) is about 4.2 eV. If we take the second term of the excited configuration ( 3 D), the energy difference is around 8.0 eV.…”