LABORATORY STUDIES OF POLYCYCLIC AROMATIC-HYDROCARBONS, FULLERENES AND LINEAR CARBON CHAINS IN AN ASTROPHYSICAL CONTEXT

The spectroscopic and photophysical properties of a number of molecula r species that have been proposed as carriers of particular features o f the interstellar extinction curve are discussed. Neutral and ionic p olycyclic aromatic hydrocarbons (PAHs), fullerenes and the carbon chai n species C-n, polyenes, polyynes and polyynyl radicals, are reviewed in this context. No difinitive assignments are given for the 220 nm in terstellar peak or the diffuse interstellar band (DIB) carriers, but t he spectral analysis concernign current data on the contending propose d carriers favours a recent suggestion that some of DIBs are due to po lyynyl radicals CnH. From the observed profiles and widths of the DIBs , it is concluded that their molecular carriers must contain more than 10-15 atoms.