Oxygen energy level diagram

Energy levels and transitions of neutral oxygen (O I): the 79 strongest classified lines below 2 µm from the NIST Atomic Spectra Database and the 43 levels they connect, each line with its vacuum wavelength, frequency and, for 73 of them, the reduced dipole matrix element derived from the NIST transition rate. Measured lifetimes, transition rates, hyperfine constants and isotope shifts from the literature are included, each with its citation.

Hover a line or a level to isolate it, click to keep it selected. Scroll to zoom, drag to move.

Download: diagram (PDF) diagram (SVG) transitions (CSV) levels (CSV) source code

Key transitions of oxygen

λ, ν from NIST level energies unless a measured frequency for this isotope is available. A: measured value or NIST. Γ/2π: natural linewidth of the upper level, 1/(2πτ).

¹⁷O hyperfine structure (I = 5/2)

Measured A, B constants; sources in the data file.

Closed and nearly closed transitions of oxygen

A transition is closed when its upper level can decay only to the level it was excited from, so the atom keeps scattering photons. “closed”: among the levels NIST lists, no other level below the upper level has the opposite parity and |ΔJ| ≤ 1, so no other electric-dipole decay exists. Otherwise the leak is the sum of the branching ratios of the other decay lines of the upper level (or 1 − branching ratio where that of the line itself has been measured), and the number of photons is 1 / leak. “≥” and “≤”: at least one possible decay path has no listed rate, so the leak is a lower limit. These numbers are derived from the branching ratios, lifetimes and rates of this page, not measured as such; the tag names the weakest of the inputs, * marks theory and ≈ a model or semi-empirical calculation. Listed: lines that start on the ground level or on a metastable level and leak at most 10 %, unless more than three possible decay paths have no listed rate. Fine-structure levels only: hyperfine and Zeeman dark states and forbidden decays without a listed rate are not considered. Select a line in the diagram for the full list of its leak channels.

Listed O transitions below 2 µm

Reduced dipole matrix elements follow the convention A = ω³|d|²/(3πε₀ħc³(2J′+1)), with J′ the upper level. Tags show where a number comes from: measured, NIST compilation, high-accuracy theory, a semi-empirical calculation (Kurucz line list, used only where no measurement or NIST value exists; typically within a factor 2), or a model calculation.

O energy levels

O⁺ ionisation limit 109837.02 cm⁻¹ = 13.61805 eV (91.044 nm)

Sources

• Harvey, Proc. R. Soc. Lond. A 285, 581 (1965), abstract (paramagnetic resonance)
• Jennerich & Tate, Phys. Rev. A 62, 042506 (2000) (Doppler-free saturated absorption near …
• Kroell, Lundberg, Persson, Svanberg, Phys. Rev. Lett. 55, 284 (1985), Table I (two-photon…
• Kurucz, R. L., Can. J. Phys. 89, 417 (2011); semi-empirical line list gf0800.pos of 2013-…
• NIST ASD
• NIST ASD O I lines table with forbidden lines (145.5 um M1, accuracy A). Note: derived: 1…
• NIST ASD O I lines table with forbidden lines (557.7, 297.2, 295.8 nm, accuracy B+). Note…
• NIST ASD O I lines table with forbidden lines (63.2 um M1, accuracy A). Note: derived: 1/…
• NIST ASD O I lines table with forbidden lines (630.0/636.4/639.2 nm, accuracy B+). Note: …
• NIST ASD level energies
• NIST ASD lines table with forbidden lines enabled; NIST gives no measurement for this lin…

Level energies are NIST ASD values. Hyperfine constants refer to 17O (I = 5/2); 16O and 18O have I = 0. Kroell et al. label their states only by term (e.g. "2p3 5s 3S", "2p3 3p 3P"); they are triplet states built on the 4S° core. NIST lists the three 5d 3D° levels at one energy (105409.008 cm^-1): the J values distinguish them. TALIF: O(2p4 3P2) + 2 x 225.65 nm -> 3p 3P, fluorescence 844.6 nm to 3s 3S°1; quenching measured by ps-TALIF in arXiv:2004.01558: k(H2O) = 1.1e-9 cm^3 s^-1 and k(He) = 0.032e-10 cm^3 s^-1 for O(3p 3P), effective lifetime 9.6 ns in atmospheric-pressure He. Forbidden-line A values are NIST critically evaluated calculations (not in the cached data/nist line file); M1 and E2 entries at the same wavelength are the two multipole parts of one line. Sources were located through arXiv/DataCite, CORE, HAL, Crossref and publisher abstract pages; the web-search quota of the session was exhausted, so coverage is limited to what those indexes exposed.

Atoms with measured data

• Lithium-632 levels, 85 lines
• Lithium-732 levels, 85 lines
• Beryllium-917 levels, 26 lines
• Sodium-2336 levels, 106 lines
• Magnesium-2418 levels, 61 lines
• Magnesium-2518 levels, 61 lines
• Potassium-3934 levels, 84 lines
• Potassium-4034 levels, 84 lines
• Potassium-4134 levels, 84 lines
• Calcium-4035 levels, 61 lines
• Calcium-4335 levels, 61 lines
• Chromium-5256 levels, 87 lines
• Chromium-5356 levels, 87 lines
• Rubidium-8536 levels, 94 lines
• Rubidium-8736 levels, 94 lines
• Strontium-8440 levels, 70 lines
• Strontium-8640 levels, 70 lines
• Strontium-8740 levels, 70 lines
• Strontium-8840 levels, 70 lines
• Cadmium-11115 levels, 21 lines
• Cadmium-11315 levels, 21 lines
• Cadmium-11415 levels, 21 lines
• Caesium-13331 levels, 79 lines
• Barium-13744 levels, 89 lines
• Barium-13844 levels, 89 lines
• Dysprosium-16139 levels, 55 lines
• Dysprosium-16239 levels, 55 lines
• Dysprosium-16339 levels, 55 lines
• Dysprosium-16439 levels, 55 lines
• Erbium-16673 levels, 90 lines
• Erbium-16773 levels, 90 lines
• Erbium-16873 levels, 90 lines
• Thulium-16972 levels, 73 lines
• Ytterbium-17118 levels, 26 lines
• Ytterbium-17318 levels, 26 lines
• Ytterbium-17418 levels, 26 lines
• Mercury-19927 levels, 47 lines
• Mercury-20127 levels, 47 lines
• Mercury-20227 levels, 47 lines

All elements: periodic table