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NIST Atomic Spectra Database Lines Data

He I: 18 Lines of Data Found
Z = 2, He 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, May 18]. National Institute of Standards and Technology, Gaithersburg, MD. DOI: https://doi.org/10.18434/T4W30F
BibTex Citation (new window)
 
Showing results for transitions involving level 1s10p 1P°1 at 24.451678459372 eV only.
λ in: vacuum
Highest relative intensity: 10
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 I (new window)
Energy Levels:  Drake 2023, Kandula et al. 2010, Martin 1973     The energy level data refer to the isotope 4He. The excitation energies of the 1snl levels with n ≤ 10 were determined here by subtracting the theoretical ionization energy listed by Drake 2023 from the experimental ionization energy of the ground level reported by Kandula et al. 2010 . The energies of the higher levels below the ionization limit were determined by fitting the extended Ritz quantum-defect expansion formula (Eq. 12.54 of Drake 2023 ) to the adjusted theoretical energies of the same 1snl SLJ series listed here as prescribed by Eqs. (12.55) through (12.57) of Drake 2023 . Uncertainties are specified relative to the ionization limit. To find uncertainties of excitation energies, combine the given uncertainties in quadrature with the uncertainty of the ground level. The 1s2p 3P° levels are given with excessive number of decimal figures required to reproduce the splittings between them, which are known very precisely. The current values of these splittings are from the calculations of Pachucki et al. 2017 . There exist many experimental reports on these splittings. No attempt has been made here to evaluate them. The doubly-excited levels above the ionization limit require a significant update. Those given here are quoted from the old compilation of Martin 1973 . There are 364 papers on energy levels of He I published between 1974 and October 2023. About half of them are devoted to core-excited levels. NIST lacks the workforce required to process such a large number of publications. The present data set was prepared by A. Kramida for the release of ASD v.5.11 in October, 2023. He I Energy Levels
Lines:  Martin 1960  He I Line Wavelengths and Classification
Transition Probabilities:  Wiese and Fuhr 2009  He I Transition Probabilities

 Observed 
 Wavelength 
 Vac (nm) 		  Unc. 
 (nm) 		  Ritz 
 Wavelength 
 Vac (nm) 		  Unc. 
 (nm) 		  Rel. 
 Int. 
(?) 		 Aki
 (s−1) 		  Acc.   Ei 
 (eV) 		    Ek 
 (eV) 		  Lower Level 
 Conf., Term, J 		  Upper Level 
 Conf., Term, J 		  Type   TP
Ref.		  Line
Ref.
                                     
50.708       0.002   50.7058027   0.0000003    10  1.5929e+07    AAA [0.00000000]       -  [24.451678459372]   1s2   1S   0   1s10p   1P°   1  T8636c73 L14922
323.2199      0.0010  323.22031567  0.00000005   0  5.1015e+05    AAA [20.615774823]      -  [24.451678459372]   1s2s   1S   0   1s10p   1P°   1  T8636c73 L14924
    809.6339811   0.0000020      1.3791e+05    AAA [22.920317359]      -  [24.451678459372]   1s3s   1S   0   1s10p   1P°   1  T8636c73  
    899.99904827  0.00000007     1.2389e+04    AAA [23.07407479777]    -  [24.451678459372]   1s3d   1D   2   1s10p   1P°   1  T8636c73  
    1 593.406304    0.000005       5.7048e+04    AAA [23.673570590]      -  [24.451678459372]   1s4s   1S   0   1s10p   1P°   1  T8636c73  
                                     
    1 733.21224844  0.00000021     1.4055e+04    AAA [23.73633503536]    -  [24.451678459372]   1s4d   1D   2   1s10p   1P°   1  T8636c73  
    2 814.857689    0.000008       2.9201e+04    AAA [24.0112149898]     -  [24.451678459372]   1s5s   1S   0   1s10p   1P°   1  T8636c73  
    3 032.3248941   0.0000006      1.3169e+04    AAA [24.042803412125]   -  [24.451678459372]   1s5d   1D   2   1s10p   1P°   1  T8636c73  
    4 759.137978    0.000016       1.3169e+04    AAA [24.1911602752]     -  [24.451678459372]   1s6s   1S   0   1s10p   1P°   1  T8636c73  
    5 114.2548766   0.0000018      1.1910e+04    AAA [24.209249793955]   -  [24.451678459372]   1s6d   1D   2   1s10p   1P°   1  T8636c73  
                                     
    8 082.804249    0.000020       1.0590e+04    AAA [24.2982859057]     -  [24.451678459372]   1s7s   1S   0   1s10p   1P°   1  T8636c73  
    8 726.299105    0.000005       1.0833e+04    AAA [24.309597381304]   -  [24.451678459372]   1s7d   1D   2   1s10p   1P°   1  T8636c73  
    14 672.96723     0.00005        6.7967e+03    AAA [24.3671800778]     -  [24.451678459372]   1s8s   1S   0   1s10p   1P°   1  T8636c73  
    16 110.440052    0.000018       1.0063e+04    AAA [24.374719544511]   -  [24.451678459372]   1s8d   1D   2   1s10p   1P°   1  T8636c73  
    32 982.95793     0.00020        3.9092e+03    AAA [24.41408807749]    -  [24.451678459372]   1s9s   1S   0   1s10p   1P°   1  T8636c73  
                                     
    38 366.97692     0.00010        9.4429e+03    AAA [24.419363117280]   -  [24.451678459372]   1s9d   1D   2   1s10p   1P°   1  T8636c73  
    293 910.048       0.010          5.6127e+02    AAA [24.44746001910]    -  [24.451678459372]   1s10s   1S   0   1s10p   1P°   1  T8636c73  
    3 225 773.7         0.7            8.5959e-01    AAA [24.4512941044573]  -  [24.451678459372]   1s10d   1D   2   1s10p   1P°   1  T8636c73  

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