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National Institute of Standards and Technology NIST Physical Measurement Laboratory
NIST Atomic Spectra Database
Ionization Energies Data

As (all spectra)
33 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 [2026, October 26]. National Institute of Standards and Technology, Gaithersburg, MD. DOI: https://doi.org/10.18434/T4W30F
BibTex Citation (new window)
 

 Ionization  Energy 
 (cm-1) 
  78 950          
  149 932          
  228 650          
  404 500          
  506 250          
  977 500          
  (1 186 000)         
  (1 452 000)         
  (1 718 000)         
  (1 992 000)         
  (2 387 000)         
  (2 686 000)         
  (3 025 000)         
  (3 371 000)         
  (3 710 000)         
  [4 739 700]         
  [5 071 800]         
  [5 427 300]         
  [5 879 000]         
  [6 242 700]         
  [6 562 000]         
  [7 353 700]         
  [7 717 040]         
  [19 010 000]         
  [20 047 000]         
  [21 178 000]         
  [22 312 000]         
  [23 694 700]         
  [24 907 000]         
  [26 508 500]         
  (27 516 760)         
  (116 528 397)         
  (121 216 456)         
Notes:
a Uncertainty of the listed value is unknown.

If you did not find the data you need, please inform the ASD Team.

[ASD Home][Lines Query][Levels Query][List of Spectra][Ground States and Ionization Energies][Bibliography][Help] NIST Physical Measurement Laboratory