blike_jl96#c1j.dat

• Spontaneous Emission: C⁺¹(i) → C⁺¹(j) + hv
• Electron Impact Excitation: C⁺¹(i) + e → C⁺¹(j) + e

 + 1         6         2    196664.7
-----------------------------------------------------------------------------
 FILE: blike_jl96#c1.dat

 ENERGY LEVELS and IONISATION POTENTIAL  
 These are taken from the book 'Tables of Spectra of H, C, N and O 
 Atoms and Ions', C. E. Moore , ed. J. W. Gallagher (CRC Press).
 The energy levels  differ by less than one cm-1 from those given in 
 the NIST data discs. The levels up to 14 inclusive are the 14 lowest 
 energy levels. The levels are ordered by increasing energy. Only levels 
 with n=2 or n=3 below the first ionisation potential are included. 
 The work of Edlen (Physica Scripta, 28, 483, 1983) did not include CII.

 
 TRANSITION PROBABILITIES 
 For allowed transitions, Yan, Taylor and Seaton (J Phys B, 20, 6399, 
 987) have published calculations done for the Opacity Project using 
 the Opacity Project close-coupling method. They point out that 
 Nussbaumer and Storey (Astron. Astrophys. 96,91 1981) used the same 
 formalism as the UCL method. All results obtained are in good 
 agreement with each other. That and other comparisons give confidence 
 that the results are unlikely to be in error due coding mistakes or 
 numerical problems. Since Yan et al do not give fine structure 
 resolved results but Nussbaumer and Storey do, the results of 
 Nussbaumer and Storey are adopted here. One small difference is that 
 the fine-structure resolved results from Nussbaumer and Storey are 
 only obtained in the SuperStructure (SS) case. Comparisons of the gf 
 values from both these calculations for transitions involving n=2 
 levels are given below. Also included are results from the earlier 
 (not so comprehensive for this ion) work  of Dankwort and Treffetz 
 (Astron. Astrophys. 65, 93, 1978) and from two more recent 
 calculations by Lennon et al (Astrophy. J 294, 200, 1985, CIV3 code)
 and Froese-Fischer (Physica Scripta 49, 323, 1994, MCHF in Breit-
 Pauli approx.).
 
 2s22p - 2s2p2   Exp       D+T    FF     Lennon  Yan    N+S(CC) (SS)
  2P       2D    0.762     0.773  0.816  0.758   0.768  0.759   0.779
  2P       2S    0.732(5%) 0.769  0.696  0.750   0.750  0.742   0.748
  2P       2P    2.94(4%)  2.908  2.994  3.063   3.06   3.028   3.085
 
 2s2p2 - 2p3     D+T    FF     Yan    N+S(CC)  (SS)
  4P      4S     2.116  2.076  2.124  2.095    2.158
  2D      2D     1.325         1.270  1.251
  2D      2P                   1.68   1.664
  2S      2P                          4.688-3
  2P      2D     0.609         0.504  0.5079
  2P      2P                   0.872  0.851
 
 The highest transition for which Nussbaumer and Storey give transition 
 probabilities is 11-14. Their data are used for the following
 1-7, 1-8, 1-9, 1-10, 2-6, 2-7, 2-8, 2-9, 2-10, 3-4, 3-5, 3-11, 3-12,
 3-14, 4-5, 4-11, 4-12, 4-14, 5-12, 5-14, 6-13, 6-14, 7-12, 7-13, 7-14,
 8-12, 8-13, 8-14, 9-11, 9-12, 9-13, 9-14, 10-11, 10-12, 10-13, 10-14, 
 11-12, 11-13, 11-14.
 Note that this list includes some intercombination lines as well as 
 values for transitions within the 2s2 2p 4P term.
 
 For the remaining allowed transitions the data from the NIST discs were 
 used. These data for the half dozen values cross checked appear to be 
 from Wiese, Smith and Glennon (NSRDS NBS 4, 1966) and are given on the
 discs as having accuracy C or worse (25% or worse).
 Their data are used for the following:
 1-11, 1-15, 2-11, 6-15, 6-16, 6-18, 7-15, 7-16, 7-17, 7-18, 
 9-16, 10-15, 10-16.
 
 Considering now the forbidden transitions, for the transition 1-2, 
 between the 1/2 and 3/2 levels of the ground 2P term, Nussbaumer and 
 Storey give a value of 2.29-6 s-1 while more recently Froese Fischer
 (J Phys B, 16, 157, 1983) has published a value of 2.049-6 s-1 from a 
 multi-configuration Hartree-Fock Breit-Pauli calculation. The latter 
 value is used here. Note that Keenan et al (Astron. Astroph. 300, 534, 
 1995) say they used the result from Lennon et al to help predict a 
 value for Ne VI but Lennon et al don't actually quote a value.   
 
 A values for the intercombination 2s2 2p2P - 2s 2p2 4P transition have 
 been published by Dankwort and Treffetz, Nussbaumer and Storey, Lennon
 et al and Froese Fischer whose 1994 paper was written after the 
 publication of measurements of the decay rates (Fang et al, Phys. Rev. 
 48A, 114, 1993). 
 The following is an adaptation of a table from the Froese Fischer paper.
 
 Decay rates (s-1) of 2s2p2 4P levels
 
                     4P1/2            4P3/2            4P5/2
 Fang et al          146.4+8.3/-9.2   11.6+0.08/-1.7   51.2+2.6/-3.5
 
 Froese Fischer      132.2            10.9             46.1
 Lennon et al        152.2            14.1             53.9
 Nussbaumer+Storey   120.8             6.95            43.2
 Dankwort+Treffetz    82.7             9.12            34.4
 
 Using agreement with experiment as a criterion, the Lennon et al values 
 are adopted for the decay of the 4P1/2 (ie 1-3 and 2-3 transitions) and 
 for the decay of the 4P5/2 (2-5 transition) while the Froese Fischer 
 value is adopted for the decay of the 2P3/2 level (1-4 and 2-4 
 transitions).

 
 EFFECTIVE COLLISION STRENGTHS
 For collisions involving transitions between the 18 levels comprising 
 the 14 lowest levels and levels 17, 18, 22 and 23 the results of Blum
 and Pradhan (Astrophys. J. SS 80, 425, 1992) are adopted. These were
 scanned into a file which was then processed into ADF04 format. 
 At an assessment meeting (Sampson, Zhang and Fontes, ADNDT 44, 97, 1994)
 there was no consensus whether the Blum and Pradhan results were more 
 accurate than the results of Lennon et al which only included 2s2 2p and 
 2s 2p2 terms. However, it was agreed that they were certainly not less 
 accurate.
 The transitions 8-14 and 11-14 are given as having 0 effective collision 
 strength.
 
 
  J Lang
  A C Lanzafame            March 1996 


  Original data set energy level reduced to include only these with collision
  rate coefficients.  Level indexing and annotation modified accordingly.

  H P Summers              12 June 1996 
-----------------------------------------------------------------------------
---------------------------------------------------------------------------------
---------------------------------------------------------------------------------

Contributors

• Jim Lang
• K P Dere
• Hong Zhang
• Douglas Sampson
• Alessandro Lanzafame
• Hugh Summers