nist_asd_2026#

A. Kramida, Yu. Ralchenko, J. Reader and NIST ASD Team, NIST Atomic Spectra Database (version 5.12), https://physics.nist.gov/asd, ionization energies (queried 2026-09-26) and levels of Ne II, Ar II, Kr II and Xe II (queried 2026-09-28) and of He I, Ne I, Ar I, Kr I and Xe I (queried 2026-10-07); Y. Ralchenko and A. Kramida, Atoms 8, 56 (2020)

Source record · Catalogue · Review register

DOI: 10.18434/T4W30F

Source kind: database

Recorded technique: The evaluated ionisation energies of the NIST Atomic Spectra Database (ionization-energies form, CSV output, eV). Each value comes from the literature references NIST lists by bibliographic key; the database’s help page says that values in square brackets are semi-empirical (interpolation or extrapolation) and values in parentheses ab initio or otherwise not from evaluated experimental data, and that the uncertainties of eV output include the cm^-1 to eV conversion (CODATA). The evaluated energy levels of the ions Ne II, Ar II, Kr II and Xe II (levels form, tab-delimited output, cm^-1 above the ion’s ground level).

Materials in structured entries: Ar, Ar+, He, He+, Kr, Kr+, Ne, Ne+, Xe, Xe+

Dataset quantities: ionization_energy, level_energy

Contents: 33 datasets; 0 formulas.

Curation notes#

The file as returned is data/external/nist_asd/ionization_energies.csv (PROVENANCE.md there, with the query); the inline points below are its strings, checked against it by tests/test_nist_asd.py. The confidence level of NIST’s uncertainties is not stated on the output or the help page: recorded as ‘not stated’. The first ionisation energy of a noble gas is to the ion’s 2P3/2 ground level; for an atom the adiabatic and vertical energies coincide (kind = adiabatic). The cations’ ionisation energies (the atoms’ second) are recorded as the ions’ own (materials He+ ... Xe+), for double ionisation later; nothing here uses them yet (TC-443).

LEVELS (queried 2026-09-28). The files as returned are data/external/nist_asd/<Ne, Ar, Kr, Xe>_II_levels.tsv (PROVENANCE.md there, with the query and the sha256 of each). The datasets level_<ion>_2P12 hold the second row of each file, the np5 2P*<1/2> level of the ion’s ground term above its 2P*<3/2> ground level: the fine-structure splitting of the ion, which added to the atom’s first ionisation energy is the atom’s second ionisation threshold. The strings are NIST’s (value and uncertainty, cm^-1), checked against the files by tests/test_nist_asd.py. NIST gives no uncertainty for the level of Kr II and of Xe II (the cell is empty: no uncertainty is recorded, and none is to be read from the number of digits), and no bibliographic key for that of Kr II. The returned files do not name the database version; it was not checked again on 2026-09-28.

NEUTRAL LINES BEYOND THE RESONANCE LINES (queried 2026-10-09). The files as returned are data/external/nist_asd/<Ne, Ar, Kr, Xe>_I_lines_nir.tsv (PROVENANCE.md there, with the query, the windows and the sha256 of each): the transitions among excited levels, with NIST’s transition probabilities and accuracy grades, in vacuum wavelengths at every wavelength (show_av=3). No dataset holds them yet; they are inputs to the sums over intermediate states of two-photon amplitudes (OEP 6, Q9; TC-983). The first query used show_av=1, which gives wavenumbers above 1000 nm, written by NIST as minus the wavenumber times 1e-9 in the nm columns; the files were replaced the same day (TC-985).

NEUTRAL LEVELS (queried 2026-10-07). The files as returned are data/external/nist_asd/<He, Ne, Ar, Kr, Xe>_I_levels.tsv (PROVENANCE.md there, with the query and the sha256 of each). The datasets level_<atom>_* hold, per atom, the levels that bound where the third-order response is off resonance: the lowest odd-parity J = 1 level (one- and three-photon) and the lowest even-parity levels of J = 0, 2 and 1 (two-photon); for helium, whose levels are LS-coupled, the singlets 1s.2p 1P*, 1s.3p 1P* and 1s.2s 1S, the triplets below them being spin-forbidden. The strings are NIST’s, checked against the files by tests/test_nist_asd.py. NIST brackets every helium level (semi-empirical): those datasets are checks. Where NIST gives no uncertainty or no bibliographic key the cell is empty (TC-862).