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NIST Atomic Spectra Database Lines Data

He II: 13 Lines of Data Found
Z = 2, H isoelectronic sequence 
Example of how to reference these results:
Kramida, A., Ralchenko, Yu., Reader, J., and NIST ASD Team (2023). NIST Atomic Spectra Database (ver. 5.11), [Online]. Available: https://physics.nist.gov/asd [2024, April 19]. National Institute of Standards and Technology, Gaithersburg, MD. DOI: https://doi.org/10.18434/T4W30F
BibTex Citation (new window)
 
Wavelength range: 400 - 500 nm
λ in: vacuum below 200 nm, air between 200 and 2000 nm, vacuum above 2000 nm
Some data for neutral and singly-charged ions are available in the Handbook of Basic Atomic Spectroscopic Data

Primary data sources
Query NIST Bibliographic Databases for
He II (new window)
Energy Levels:  Yerokhin & Shabaev 2015, Erickson 1977     The data refer to the isotope 4He. Erickson's theoretical values of ionization energies were scaled to the CODATA-2018 values of the fundamental constants and then subtracted from the ground-state ionization energy given by Yerokhin & Shabaev 2015 . Additional corrections were applied to the nS levels, as described by Kramida et al. 2008 . The n = 2 energy levels were taken directly from Yerokhin & Shabaev 2015 . Their uncertainties are given for excitation energies from the ground state; for the rest of the levels, uncertainties are given for separations from the ionization limit. The present data set was prepared by A. Kramida (unpublished) for the release of ASD v. 5.10 in September 2022. He II Energy Levels
Lines:  Yerokhin & Shabaev 2015, Erickson 1977     Wavelengths were calculated from the energy levels. He II Line Wavelengths and Classification
Transition Probabilities:  Jitrik & Bunge 2004     The data of Jitrik & Bunge 2004 have been scaled to the CODATA-2018 values of the fundamental constants by A. Kramida for the release of ASD v. 5.10 in October 2022. He II Transition Probabilities

 Observed 
 Wavelength 
 Air (nm) 		  Ritz 
 Wavelength 
 Air (nm) 		  Unc. 
 (nm) 		  Rel. 
 Int. 
(?) 		 Aki
 (s−1) 		  Acc.   Ei 
 (cm−1) 		    Ek 
 (cm−1) 		  Lower Level 
 Conf., Term, J 		  Upper Level 
 Conf., Term, J 		  Type   TP
Ref.		  Line
Ref.
                                   
  468.5376850   0.0000024     9.3899e+07    AA (390 140.8249696)   -  (411 477.853680)    3p   2P°   1/2   4d   2D   3/2  T7771  
  468.5407226   0.0000023     4.9070e+07    AA (390 140.964517)    -  (411 477.8548989)   3s   2S   1/2   4p   2P°   3/2  T7771  
  468.5524404   0.0000023     9.7968e+06    AA (390 140.8249696)   -  (411 477.1817529)   3p   2P°   1/2   4s   2S   1/2  T7771  
  468.5568006   0.0000023     4.9080e+07    AA (390 140.964517)    -  (411 477.1227550)   3s   2S   1/2   4p   2P°   1/2  T7771  
  468.5703850   0.0000023     2.0605e+08    AA (390 142.55757536)  -  (411 478.097267)    3d   2D   3/2   4f   2F°   5/2  T7771  
                                   
  468.5704380   0.0000024     1.1268e+08    AA (390 142.5604306)   -  (411 478.097707)    3p   2P°   3/2   4d   2D   5/2  T7771  
  468.5757080   0.0000023     5.5646e+05    AA (390 142.55757536)  -  (411 477.8548989)   3d   2D   3/2   4p   2P°   3/2  T7771  
  468.5757975   0.0000024     1.8780e+07    AA (390 142.5604306)   -  (411 477.853680)    3p   2P°   3/2   4d   2D   3/2  T7771  
  468.5804092   0.0000023     2.2076e+08    AA (390 143.13600712)  -  (411 478.219277)    3d   2D   5/2   4f   2F°   7/2  T7771  
  468.5830890   0.0000023     1.4717e+07    AA (390 143.13600712)  -  (411 478.097267)    3d   2D   5/2   4f   2F°   5/2  T7771  
                                   
  468.5884123   0.0000023     5.0091e+06    AA (390 143.13600712)  -  (411 477.8548989)   3d   2D   5/2   4p   2P°   3/2  T7771  
  468.5905553   0.0000023     1.9602e+07    AA (390 142.5604306)   -  (411 477.1817529)   3p   2P°   3/2   4s   2S   1/2  T7771  
  468.5917885   0.0000023     5.5680e+06    AA (390 142.55757536)  -  (411 477.1227550)   3d   2D   3/2   4p   2P°   1/2  T7771  

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