Introduction
These pages are based on the final report for the Engineering and Physical Sciences Research Council (EPSRC) grant GR/M70841/01 "Identification and Determination of Carbon Containing Transient Species"
The key advance made possible with this grant is in understanding one of the key absorptions found in carbon rich flames and plasmas, the A – X absorption of C3. This strong and extensive absorption in the UV has been known since the 19th century but detailed analysis has proved elusive. Using a combination of experimental measurements, high level ab initio calculations and exact calculations of rovibronic energy levels a quantitative description of the upper electronic state has been obtained for the first time and the detailed analysis of the ground state has been greatly extended.