atomic data for Be seq

[Gary J. Ferland]

Title:	
R-matrix electron-impact excitation data for the Be-like iso-electronic sequence
Authors:	
Fernández-Menchero, L.; Del Zanna, G.; Badnell, N. R.
Affiliation:	
AA(Department of PhysicsUniversity of Strathclyde, Glasgow, G4 0NG, UK luis.fernandez-menchero@strath.ac.uk ), AB(Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, CB3 0WA, UK), AC(Department of PhysicsUniversity of Strathclyde, Glasgow, G4 0NG, UK luis.fernandez-menchero@strath.ac.uk )
Publication:	
Astronomy & Astrophysics, Volume 566, id.A104, 11 pp. (A&A Homepage)
Publication Date:	
06/2014
Origin:	
EDP Sciences
Astronomy Keywords:	
atomic data, techniques: spectroscopic
DOI:	
10.1051/0004-6361/201423864
Bibliographic Code:	
2014A&A...566A.104F
Abstract


Aims: Emission lines from ions in the Be-like isoelectronic sequence can be used for 
reliable diagnostics of temperature and density of astrophysical and fusion plasmas over a 
wide range of temperatures. Surprisingly, interpolated data is all that is available for a 
number of astrophysically important ions. 

Methods: We have carried out intermediate coupling frame transformation R-matrix 
calculations which include a total of 238 fine-structure levels in both the configuration 
interaction target and close-coupling collision expansions. These arise from the 
configurations 1s2 2 {s, p} nl with n = 3-7, and l = 0-4 for n ? 5 and l = 0-2 for n = 6,7. 

Results: We obtain ordinary collision strengths and Maxwell-averaged effective collision 
strengths for the electron-impact excitation of all the ions of the Be-like sequence, from 
B+ to Zn26+. We compare with previous R-matrix calculations and interpolated values for 
some benchmark ions. We find good agreement for transitions n = 2-2 with previous R-
matrix calculations but some disagreements with interpolated values. We also find good 
agreement for the most intense transitions n = 2-3 which contribute via cascade to the (n 
= 2) diagnostic radiating levels.

These data are made available in the archives of APAP via http://www.apap-network.org 
and OPEN-ADAS via http://open.adas.ac.uk

GJF: Collision rates for some C III lines differ by 2x from previous work.