The CHIANTI database consists of 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.

 
%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 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.

 
%observed energy levels: Fuhr, J.R. et al., "NIST Atomic Spectra Database" Ver. 2.0, March 1999,
    NIST Physical Reference Data
%A-values (allowed transitions): Tayal S.S., J.Phys.B 32, 5311, 1999
%A-value (ground transition): Johnson C.T., Kingston A.E., Dufton P.L., MNRAS 220, 155, 1986
%A-values (involving levels 17 to 20): Young P.R., unpublished Superstructure calculation
%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, Feb 2000

s_4.splups (electron collision data)

contains the spline fits to the electron collision strengths scaled according the rules formulated by 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.

 

%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 (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

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

s_4_table.html (html table)


Last revised by G. Del Zanna on 4-Sep-2009