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

I (all spectra)
53 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) 
  84 294.9         
  154 304.0         
  238 500           
  325 500           
  415 510           
  [599 800]          
  [706 600]          
  1 216 400           
  (1 379 000)          
  (1 589 000)          
  (1 782 000)          
  (1 992 000)          
  (2 250 000)          
  (2 476 000)          
  (2 702 000)          
  (2 944 000)          
  (3 170 000)          
  (4 073 000)          
  (4 315 000)          
  (4 589 000)          
  (4 847 000)          
  (5 235 000)          
  (5 509 000)          
  (6 146 000)          
  [6 458 600]          
  (11 268 000)          
  (11 872 000)          
  (12 526 000)          
  (13 219 000)          
  (13 873 000)          
  (14 615 000)          
  (15 413 000)          
  (16 123 000)          
  (16 881 000)          
  (17 591 000)          
  (19 607 000)          
  (20 245 000)          
  (20 954 000)          
  (21 616 000)          
  (22 874 000)          
  (23 600 000)          
  (24 971 000)          
  [25 693 000]          
  (59 177 000)          
  (61 000 000)          
  (63 000 000)          
  (64 879 000)          
  (69 372 000)          
  (71 517 000)          
  (74 171 000)          
  (75 986 300)          
  (312 273 650)          
  (320 375 900)          
Notes:
a Uncertainty of the listed value is unknown.

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

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