Open AccessEffective collision strengths for forbidden transitions among the 3s 2 3p 3 fine‐structure levels of Cl III III
Author(s) -
Ramsbottom C. A.,
Bell K. L.,
Keenan F. P.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02648.x
Subject(s) - physics , collision , atomic physics , coupling (piping) , electron , ground state , excitation , range (aeronautics) , eigenvalues and eigenvectors , state (computer science) , matrix (chemical analysis) , quantum mechanics , algorithm , computer security , computer science , mechanical engineering , materials science , engineering , composite material
Effective collision strengths for the 10 astrophysically important fine‐structure forbidden transitions among the 4 S o , 2 D o and 2 P o levels in the 3s 2 3p 3 configuration of Cl iii are presented. The calculation employs the multichannel R‐matrix method to compute the electron‐impact excitation collision strengths in a close‐coupling expansion, which incorporates the lowest 23 LS target eigenstates of Cl iii . These states are formed from the 3s 2 3p 3 , 3s3p 4 , 3s 2 3p 2 3d and 3s 2 3p 2 4s configurations. The Maxwellian‐averaged effective collision strengths are presented graphically for all 10 fine‐structure transitions over a wide range of electron temperatures appropriate for astrophysical applications [log T (K)=3.3−log T (K)=5.9]. Comparisons are made with the earlier seven‐state close‐coupling calculation of Butler & Zeippen, and in general excellent agreement is found in the low‐temperature region where a comparison is possible [log T (K)=3.3−log T (K)=4.7]. However, discrepancies of up to 30 per cent are found to occur for the forbidden transitions which involve the 4 S o ground state level, particularly for the lowest temperatures considered. At the higher temperatures, the present data are the only reliable results currently available.