TY  - JOUR
SP  - 717 
N2  - A new calculation of rate coefficients for electron collisional excitation of Fe XII is presented and compared to earlier calculations. Significant differences are found with all earlier work due to the inclusion of resonance processes that have not previously been considered and to the use of the intermediate coupling frame transformation method. The resulting dataset of collision strengths is shown to resolve many of the outstanding discrepancies between theory and solar observations. In particular, density sensitive line ratios in Fe XII now indicate electron densities close to those derived from other ions of comparable ionization potential.
KW  - atomic data
KW  -  Sun : corona
KW  -  techniques : spectroscopic
KW  -  EXTREME-ULTRAVIOLET SPECTRUM
KW  -  FINE-STRUCTURE TRANSITIONS
KW  -  LINE INTENSITY RATIOS
KW  -  SOLAR ACTIVE-REGION
KW  -  GROUND CONFIGURATION
KW  -  CROSS-SECTIONS
KW  -  IDENTIFICATIONS
KW  -  ASTROPHYSICS
KW  -  SERTS-95
KW  -  CORONA
VL  - 433
EP  -  730
UR  - https://discovery.ucl.ac.uk/id/eprint/10064/
AV  - public
TI  - Atomic data from the IRON project - LVIII. Electron impact excitation of Fe XII
ID  - discovery10064
IS  - 2
SN  - 0004-6361
JF  - ASTRON ASTROPHYS
PB  - E D P SCIENCES
A1  - Storey, PJ
A1  - Del Zanna, G
A1  - Mason, HE
A1  - Zeippen, CJ
Y1  - 2005/04//
ER  -