NIST Physical Measurement Laboratory Handbook of Basic Atomic Spectroscopic Data

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Atomic Data for Helium (He)

Atomic Number = 2

Atomic Weight = 4.002602

Reference E95

  Isotope   Mass   Abundance   Spin   Mag Moment 


The spectroscopic data below are for the isotope 4He.

He I  Ground State 1s2 1S0
       Ionization energy  198310.669 cm-1 (24.587387 eV)   Ref. M02

He II Ground State 1s 2S1/2
       Ionization energy  438908.8789 cm-1 (54.417760 eV)   Ref. MK00b