Electronic spectroscopy of carbon chains and relevance to astrophysics
Abstract
Laboratory measurements of electronic transitions in carbon chains are presented. Guided by the results found in neon matrices, gas-phase spectra have been obtained with two different experimental approaches. Electronic transitions of neutral carbon chains are detected in a supersonic slit jet plasma by cavity ring-down (CRD) spectroscopy, and those of mass-selected anions are probed by resonant two-colour electron photodetachment. The successful combination of matrix and gas-phase experiments is demonstrated for the examples of C6H and C14H-. These, and other previous measure-ments on electronic transitions of long carbon chains in the gas phase, arecompared with the tabulated wavelengths of the diffuse interstellar bands. In the case of the A2Πu–X2Πg transition of C7- the origin and three intense bands in the gas-phase spectrum match, within ±0.2 nm error limits, diffuse interstellar bands which have comparable FWHMs and equivalent widths.