S IV - VERSION 5.1

The CHIANTI database consists of 4 primary ASCII files for each ion in the database.

• s_4.elvlc (energy levels)

  contains the energy levels in cm^(-1) It includes both experimental data and theoretical values of the levels energies.

  References:

  %observed energy levels: Fuhr, J.R. et al., "NIST Atomic Spectra Database" Ver. 2.0, March 1999, 
      NIST Physical Reference Data
  %theoretical energy levels: Tayal S.S., 2000, ApJ, 530, 1091
  %produced as part of the Arcetri/Cambridge/NRL 'CHIANTI' atomic data base collaboration
  %
  %  P.R. Young, Feb 2000
  

  
  

• s_4.wgfa (radiative data)

  contains wavelengths, gf and A values for each transition. Wavelengths are based on experimental level energies where available; wavelengths calculated from theoretical energies are less accurate and are given as negative values.

  References:

  %observed energy levels: Fuhr, J.R. et al., "NIST Atomic Spectra Database" Ver. 2.0, March 1999,
      NIST Physical Reference Data
  %A-values all allowed transitions between 3s2.3p and 3s.3p^2, 3s2.3d, 3s2.4s 
      configurations (levels up to 13): Hibbert, A., Brage, T., Fleming, J. 2002, MNRAS 333, 885
  %A-values all other allowed transitions: Tayal S.S., J.Phys.B 32, 5311, 1999
  %A-values ground transition: Johnson C.T., Kingston A.E., Dufton P.L., MNRAS 220, 155, 1986
  %A-values transitions involving levels 17 to 20: Young P.R., unpublished Superstructure calculation
  %comment: An error in Table 7 of Hibbert et al. 2002 has been corrected. The A-value for 
      the 2-6 transition is given as 2.251(+8) when it should be 2.251(+7).
  %comment: Note that Tayal gives f values rather than gf values so I had to multiply his 
      numbers by the stat. weight of the lower level.
  %comment: No A-values are available in the literature for the 4F levels 17 to 20. I've run 
      Superstructure with a model of the ion containing the 10 configurations of Tayal's model. 
      The gf and A-values were computed with observed energy levels.
  %produced as part of the Arcetri/Cambridge/NRL 'CHIANTI' atomic data base collaboration
  %
  %  P.R. Young -  Jan. 2003
  

  
  

• s_4.splups (electron collision data)

  contains the spline fits to the electron collision strengths scaled according to Burgess and Tully (1992). Accurate replication of the temperature averaged collision strength over a wide range of temperatures can be accomplished with the data in this file.

  References:

  
  %filename: s_4.upsdat
  %oscillator strengths: Tayal S.S., 1999, J.Phys.B, 32, 5311
  %effective collision strengths: Tayal S.S., 2000, ApJ, 530, 1091
  %comment: The upsilons provided by Tayal were only given to 3 decimal places 
      and so where the upsilons are small, accuracy is lost.
      I have not fitted the transitions from levels 3 to 5 up to levels 51 
      to 52, as the decimal place problem is particularly bad for these 
      transitions.
      I have fitted all transitions involving levels 1 to 5, and level 20 
      (other than the ones mentioned above). Level 20 is metastable.
      Tayal only tabulates transitions from levels 1 to 10 to higher levels. 
      The transitions from levels 11-52 to level 20 may have a significant 
      affect on the level balance.
      In general, there were no problems in fitting this data-set. However 
      the allowed transitions between levels 3 to 5 and levels 40 to 42 had 
      high temperature limit points that were significantly higher than 
      suggested by the actual upsilons (around a factor 2 higher). 
  %comment: effective collision strengths were provided in the temperature range 4.0 < Log T < 5.6
  %produced as part of the Arcetri/Cambridge/NRL 'CHIANTI' atomic data base collaboration
  %
  % Peter Young, Jul 2000
  

  
  

• s_4.psplups (electron collision data)

  contains the spline fits to the scaled proton collision strengths.

  References:

  
  %filename: s_4.psplups
  %rates: Bely, O., Faucher, P., 1970, A&A 6, 88
  %energies: Observed energies from .elvlc file.
  %produced as part of the Arcetri/Cambridge/NRL 'CHIANTI' atomic data base collaboration
  %
  % Peter Young   8-Jun-2001
  

  
  

  The html table below contains the radiative data of the brightest lines sorted in wavelength

  
  

• s_4_table.html (html table)