NIST Atomic Ionization Energies Output

NIST Atomic Spectra Database Ionization Energies Data Ar (all spectra) 18 Data Rows Found	Example of how to reference these results: Kramida, A., Ralchenko, Yu., Reader, J., and NIST ASD Team (2024). NIST Atomic Spectra Database (ver. 5.12), [Online]. Available: https://physics.nist.gov/asd [2025, November 17]. National Institute of Standards and Technology, Gaithersburg, MD. DOI: https://doi.org/10.18434/T4W30F BibTex Citation (new window)

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At. num | El. Name | Isoel. Seq. | Ground Shells (a) | Ground Level |        Ionization Energy (eV)        |   Uncertainty (eV)   | References
--------|----------|-------------|-------------------|--------------|--------------------------------------|----------------------|-----------
     18 | Argon    | Ar          | [Ne].3s2.3p6      | 1S0          |            15.7596119                |          0.0000005   |     L9217
     18 | Argon    | Cl          | [Ne].3s2.3p5      | 2P*<3/2>     |            27.62967                  |          0.00012     |     L8844
     18 | Argon    | S           | [Ne].3s2.3p4      | 3P<2>        |           [40.735]                   |          0.012       |     L8114
     18 | Argon    | P           | [Ne].3s2.3p3      | 4S*<3/2>     |           [59.58]                    |          0.18        |    L11770
     18 | Argon    | Si          | [Ne].3s2.3p2      | 3P0          |           [74.84]                    |          0.17        |    L11770
     18 | Argon    | Al          | [Ne].3s2.3p       | 2P*<1/2>     |            91.290                    |          0.010       |    L12277
     18 | Argon    | Mg          | [Ne].3s2          | 1S0          |          [124.41]                    |          0.06        |    L11770
     18 | Argon    | Na          | [Ne].3s           | 2S<1/2>      |          [143.4567]                  |          0.0012      |     L4344
     18 | Argon    | Ne          | 1s2.2s2.2p6       | 1S0          |          [422.60]                    |          0.06        |    L11770
     18 | Argon    | F           | 1s2.2s2.2p5       | 2P*<3/2>     |          [479.76]                    |          0.12        | L11242c99
     18 | Argon    | O           | 1s2.2s2.2p4       | 3P<2>        |          [540.4]                     |          0.6         |    L11770
     18 | Argon    | N           | 1s2.2s2.2p3       | 4S*<3/2>     |          [619.0]                     |          0.4         |    L11770
     18 | Argon    | C           | 1s2.2s2.2p2       | 3P0          |          [685.5]                     |          0.3         |    L11770
     18 | Argon    | B           | 1s2.2s2.2p        | 2P*<1/2>     |          [755.13]                    |          0.22        |    L11770
     18 | Argon    | Be          | 1s2.2s2           | 1S0          |          [855.5]                     |          0.3         |    L11770
     18 | Argon    | Li          | 1s2.2s            | 2S<1/2>      |          (918.375)                   |          0.007       | L16264c99
     18 | Argon    | He          | 1s2               | 1S0          |         (4120.66559)                 |          0.00022     |    L21139
     18 | Argon    | H           | 1s                | 2S<1/2>      |         (4426.22407)                 |          0.00004     |    L19200
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Notes:
(a) Designations used in the ground shell lists:
     [Ne] = 1s2.2s2.2p6

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