eprintid: 10064 rev_number: 56 eprint_status: archive userid: 599 dir: disk0/00/01/00/64 datestamp: 2008-09-11 11:41:10 lastmod: 2021-10-10 23:19:00 status_changed: 2008-09-11 11:41:10 type: article metadata_visibility: show item_issues_count: 0 creators_name: Storey, PJ creators_name: Del Zanna, G creators_name: Mason, HE creators_name: Zeippen, CJ title: Atomic data from the IRON project - LVIII. Electron impact excitation of Fe XII subjects: 11200 subjects: 11000 divisions: UCL divisions: B04 divisions: C06 divisions: F60 keywords: atomic data, Sun : corona, techniques : spectroscopic, EXTREME-ULTRAVIOLET SPECTRUM, FINE-STRUCTURE TRANSITIONS, LINE INTENSITY RATIOS, SOLAR ACTIVE-REGION, GROUND CONFIGURATION, CROSS-SECTIONS, IDENTIFICATIONS, ASTROPHYSICS, SERTS-95, CORONA abstract: 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. date: 2005-04 publisher: E D P SCIENCES vfaculties: VMPS rae2008: 19 oa_status: green primo: open primo_central: open_green article_type_text: Article verified: verified_batch elements_source: Web of Science elements_id: 22876 doi: 10.1051/0004-6361:20041771 lyricists_name: Storey, Peter lyricists_id: PJSTO59 full_text_status: public publication: ASTRON ASTROPHYS volume: 433 number: 2 pagerange: 717 - 730 refereed: TRUE issn: 0004-6361 citation: Storey, PJ; Del Zanna, G; Mason, HE; Zeippen, CJ; (2005) Atomic data from the IRON project - LVIII. Electron impact excitation of Fe XII. ASTRON ASTROPHYS , 433 (2) 717 - 730. 10.1051/0004-6361:20041771 <https://doi.org/10.1051/0004-6361%3A20041771>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10064/1/10064.pdf