Atomic energy level diagrams

Interactive site: https://muuuun.github.io/atom-energy-levels/

Interactive Grotrian diagrams for the periodic table. The landing page is a clickable periodic table: 90 elements have a page built from the NIST Atomic Spectra Database (strongest classified lines below 2 µm, with wavelengths and dipole matrix elements derived from NIST transition rates). Twelve elements used in cold-atom, tweezer, clock and ion-trap labs (Li, Be, Na, Mg, K, Ca, Rb, Sr, Cs, Ba, Yb, Dy; 22 isotopes) additionally carry measured lifetimes, transition rates, hyperfine constants and isotope shifts with citations. On every page: hover a line or a level to isolate it, click to pin, filter by transition type (E1, intercombination, M1, E2, M2, Rydberg).

Pipeline

python3 fetch_all.py       # download / cache the NIST ASD tables of every neutral atom
python3 compute.py all     # (or: curated | auto | <key> ...)  NIST ASD + data/literature/*.json (+ ARC, pairinteraction for alkalis) -> data/<key>/atom.json, *.csv
python3 plot.py all        # -> docs/<slug>/diagram.svg|pdf, preview.png, data.json
python3 build_site.py      # -> docs/**/index.html, sitemap.xml
python3 stats.py           # -> data/provenance.md  (which source supplied how many numbers)

species.py lists the curated species; every other element gets an automatic NIST-only entry. Adding a curated one is a dictionary entry: kind="nist" needs only the element symbol, an energy cut and the isotope; kind="alkali" additionally uses ARC so that every E1-allowed pair gets a matrix element.

Where the numbers come from

Priority for every number: measurement (data/literature/<El>.json, each value with citation and URL) > NIST ASD > high-accuracy theory quoted in the literature > ARC model potential (alkalis only). Each value carries its tier in the CSV files and on the site (measured, NIST, theory, model calc.); on the diagrams * marks theory and ≈ a model value.

Quantity	Source
Level energies, wavelengths, frequencies	NIST ASD level energies; measured isotope-specific frequencies where available
Transition rates, matrix elements	measured > NIST ASD > all-order theory (UDel portal, Safronova et al.) > ARC
Lifetimes	measured > theory > ARC sum of rates (alkalis)
Hyperfine constants, isotope shifts	measurements (Allegrini et al. 2022 survey, Steck, original papers)
Rydberg term energies	pairinteraction (Rb); ARC quantum defects hung from the NIST ionisation limit (other alkalis)

Current counts are in data/provenance.md; per-species cross-checks in data/<key>/validation.txt.

Known caveats: NIST level energies refer to the natural isotope mixture, so wavelengths of minority isotopes are off by the isotope shift (listed where measured); conflicts between sources are recorded in the notes / conflicts fields of the literature files; some old lifetime measurements (Cs n ≥ 8) are probably less accurate than modern theory but are kept as primary.