A mixture of hydrogenated amorphous carbon grains and PAH molecules: a candidate for the unidentified infrared bands?

Transmission spectra of hydrogenated amorphous carbon (HAC) and different PAH collections have been measured in the laboratory to study the question of whether or not they can account for unidentified IR bands. It is found that transmission spectra of mixtures composed by HAC and PAH collections match the astronomical observations, although they do not fit the entire family of unidentified IR bands. The laboratory data are used in emission to simulate the spectrum of the planetary nebula NGC 7027, showing good agreement. 36 references.