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Spectroscopic characterization of carbon radicals, ions, and cluster ions

English title Spectroscopic characterization of carbon radicals, ions, and cluster ions
Applicant Maier John Paul
Number 100019
Funding scheme Project funding
Research institution Physikalische Chemie Departement Chemie Universität Basel
Institution of higher education University of Basel - BS
Main discipline Physical Chemistry
Start/End 01.04.2003 - 31.03.2005
Approved amount 779'618.00
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Keywords (9)

carbon-clusters; radicals; electronic-spectra; ions; interstellar molecules; Spectroscopy; laser-methods; interstellar-chemistry; electronic-structure

Lay Summary (English)

Lay summary
The principle aim of the project is to spectroscopically characterizechemically and astrophysically interesting radicals and ions containingdominantly carbon. A number of techniques is used or being developed tomeasure the electronic spectra in the gas phase. These then provide themeans of identifying the species in terrestrial and space environments,and the details of the spectral features enable information of theconditions in such hostile regions to be inferred as well as thefundamental knowledge on the electronic structure of the molecule. Thespecies of primary focus are carbon chains, rings, fullerenes, theirsimple derivatives including a few hydrogens, nitrogen or such, and ions.The reactive species are prepared in the gas phase by means of plasmasproduced in supersonic free jets, often from simple precursors asacetylene. Sensitive laser methods are used to detect the electronictransitions. Measurements of the electronic spectra in neon matrices withmass-selected beams often provides the basis of the gas phase studies.Some of the recent results are as follows.The electronic spectrum of a non-linear, planar carbon chain radical,C6H4+, could be obtained following its in synthesis in a supersonic plasmadischarge with acetylene as precursor. The identification of the structurewas by a rotational analysis of the spectrum combined with theoreticalcalculations. This constitutes a breakthrough in our studies as we arebeginning to observe and identify the electronic spectra of non-linearchains.The electronic spectra of polyacetylenes, HC2n+1H, n=3-9, could berecorded in the gas phase by a two photon excitation-ionisation scheme,following production in an acetylene plasma. The trends in the wavelengthof the transition with size of the chain enables the bulk properties ofsuch nanowires to be made. They will be semiconductors; terminating theends with sulfur instead of hydrogen leads to conducting nanowires. Thisillustrates the relevance of such spectroscopic studies for nanoscienceapplications.The first spectroscopic characterization of a polyatomic bare carboncation, cyclic and linear C6+, has been carried out in neon matrices at 6Kby means of mass-selection. Electronic and infrared transitions could beobserved and assigned. The C6+ cation was generated from precursors suchas perchlorobenzene in ion sources. This opens the way to gas phasestudies.
Direct link to Lay Summary Last update: 21.02.2013

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Associated projects

Number Title Start Funding scheme
107386 Spectroscopic characterization of carbon radicals, ions, and cluster ions 01.04.2005 Project funding
63459 Spectroscopic characterization of carbon radicals, ions, and cluster ions 01.04.2001 Project funding