S IV - VERSION 11.0

The CHIANTI database has the following primary ASCII files for this ion:

s_4.elvlc (energy levels)

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

 
%filename: s_4.elvlc                              
%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

contains wavelengths, gf and A values of the transitions. The wavelengths are based on the experimental energy levels and should be the best available. Wavelengths calculated from the theoretical energies are of an indeterminate accuracy and their values are presented as negative values of the calculated wavelength.

 
%filename: s_4.wgfa
%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%A-values transitions involving levels 17 to 20: Young P.R., unpublished Superstructure calculation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
%File processed with wgfa_tidy by pryoung on  6-Mar-2019
%File processed with wgfa_tidy by pryoung on 31-May-2023

s_4.scups (electron collision data)

contains the effective electron collision strengths scaled according to the rules formulated by Burgess and Tully (1992).

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

s_4.psplups (proton collision data)

contains the spline fits to the scaled proton collision strengths.

 

%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)