A theoretical investigation of the possible detection of C24 in space

Astronomical infrared spectral features at similar to 6.6, 9.8 and 20 mu m have recently been suggested as being due to the planar graphene form of C-24 carbon cluster. Here, we report density functional theory and coupled cluster calculations on wavefunctions stability, relative energies and infrared spectra of four different types of C-24 isomers, including the graphene and fullerene forms. The types of vibrational motions under these bands are also discussed. Among the four isomers, we find that the astronomical data are best approximated by the graphene form of C-24.