Laboratory measurements on molecules of astrophysical interest

Abstract

The infra-red absorption bands of a representative polycyclic aromatic hydrocarbon (PAH) molecule, coronene, have been examined in the laboratory at various temperatures up to 240 °C. This paper is devoted to a systematic analysis of the temperature variations of the integrated band intensity. A tentative interpretation of the observed behaviour is given in terms of anharmonicity effects. These new laboratory results may be helpful in the context of the attribution of the «unidentified» infra-red band to PAH molecules. In addition, for the first time thermal-emission spectra of three different PAHs recorded at 240 °C are presented.