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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, June 6]. National Institute of Standards and Technology, Gaithersburg, MD. DOI: https://doi.org/10.18434/T4W30F
BibTex Citation (new window)
 

 Ionization  Energy 
 (eV) 
  4.0727411              
  [22.4]                   
  [33.5]                   
  (39.1)                   
  (50.0)                   
  (67.0)                   
  (80.0)                   
  (106.0)                   
  (120.0)                   
  (179.0)                   
  (200.0)                   
  (222.1)                   
  (245)                     
  (269)                     
  (293)                     
  (324)                     
  (349)                     
  (375)                     
  (400)                     
  (530)                     
  (560)                     
  (590)                     
  (620)                     
  (690)                     
  (720)                     
  (810)                     
  (850)                     
  (910)                     
  (980)                     
  (1 040)                     
  (1 110)                     
  (1 180)                     
  (1 250)                     
  (1 320)                     
  (1 380)                     
  (1 460)                     
  (1 530)                     
  (1 600)                     
  (1 670)                     
  (1 740)                     
  (1 810)                     
  (2 119)                     
  (2 182)                     
  (2 247)                     
  (2 317)                     
  (2 384)                     
  (2 450)                     
  (2 564)                     
  (2 631)                     
  (2 706)                     
  (2 774)                     
  (3 049)                     
  (3 115)                     
  (3 190)                     
  (3 257)                     
  (3 556)                     
  (3 635)                     
  (3 828)                     
  [3 907]                     
  (6 365)                     
  (6 516)                     
  (6 678)                     
  (6 849)                     
  (7 013)                     
  (7 172)                     
  (7 500)                     
  (7 670)                     
  (7 850)                     
  (8 020)                     
  (8 500)                     
  (8 640)                     
  (8 800)                     
  (8 950)                     
  (9 890)                     
  (10 070)                     
  (10 420)                     
  (10 590)                     
  (22 330)                     
  (22 730)                     
  (23 170)                     
  (23 570)                     
  (27 060)                     
  (27 590)                     
  (28 260)                     
  (28 683.4)                   
  (113 821.9)                   
  (115 857.5)                   
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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