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Electronic spectra of cold, large interstellar ions (ElecSpecIons)
Date du début: 1 mai 2010, Date de fin: 30 avr. 2015 PROJET  TERMINÉ 

The purpose of this project is to measure for the first time gas-phase spectra of large carbon containing cations, at low temperatures, which are of astrophysical importance. Knowledge of electronic spectroscopy of such molecules is also of pertinence in a number of areas of chemistry and physics, enabling their identification in planetary atmospheres, flames and plasmas and as intermediates in chemical reaction dynamics. This project is interdisciplinary, bridging the areas of chemistry, physics, and astrophysics. It encompasses state of the art techniques of chemical physics and aims at obtaining information to solve the long standing enigma in observational astronomy, the identification of some of the molecules causing absorption of starlight in diffuse interstellar clouds. The project uses ion trapping technology, whereby mass-selected species are held in a radio-frequency field and the vibrations and rotations are relaxed by collisions with cold helium to typical interstellar temperatures of 10-30 K. The electronic spectra of a number of cations, selected on the basis of their special properties including those of bare carbon chains, rings and fullerenes, polycyclic aromatic hydrocarbon cations and their protonated forms will be measured using new detection schemes. The first approach is based on photo-induced charge transfer which is turned on upon laser excitation and the second uses the possibility of rare-gas complexation in the ground but not excited state.