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NIST Atomic Spectra Database
Ionization Energies Data

Fr (all spectra)
87 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) 
  32 848.872         
  [181 000]            
  [270 000]            
  (315 000)            
  (403 000)            
  (540 000)            
  (645 000)            
  (855 000)            
  (968 000)            
  (1 444 000)            
  (1 613 000)            
  (1 791 000)            
  (1 976 000)            
  (2 170 000)            
  (2 363 000)            
  (2 613 000)            
  (2 815 000)            
  (3 025 000)            
  (3 226 000)            
  (4 255 000)            
  (4 507 000)            
  (4 760 000)            
  (5 010 000)            
  (5 560 000)            
  (5 830 000)            
  (6 570 000)            
  (6 860 000)            
  (7 320 000)            
  (7 870 000)            
  (8 410 000)            
  (8 969 000)            
  (9 520 000)            
  (10 070 000)            
  (10 610 000)            
  (11 160 000)            
  (11 780 000)            
  (12 340 000)            
  (12 900 000)            
  (13 500 000)            
  (14 000 000)            
  (14 600 000)            
  (17 091 000)            
  (17 599 000)            
  (18 123 000)            
  (18 688 000)            
  (19 228 000)            
  (19 761 000)            
  (20 680 000)            
  (21 220 000)            
  (21 825 000)            
  (22 374 000)            
  (24 592 000)            
  (25 124 000)            
  (25 729 000)            
  (26 269 000)            
  (28 681 000)            
  (29 318 000)            
  (30 875 000)            
  [31 512 800]            
  (51 337 000)            
  (52 555 000)            
  (53 862 000)            
  (55 241 000)            
  (56 564 000)            
  (57 846 000)            
  (60 508 000)            
  (61 855 000)            
  (63 339 000)            
  (64 702 000)            
  (68 525 000)            
  (69 702 000)            
  (71 001 000)            
  (72 203 000)            
  (79 800 000)            
  (81 220 000)            
  (84 027 000)            
  (85 374 000)            
  (180 112 000)            
  (183 322 000)            
  (186 879 000)            
  (190 137 000)            
  (218 286 000)            
  (222 528 000)            
  (227 924 000)            
  (231 347 000)            
  (918 035 500)            
  (934 454 000)            
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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