VACUUM ULTRAVIOLET EXTINCTION MEASUREMENTS ON COSMIC DUST ANALOG CARBON GRAINS

In this paper we present the results of new systematic spectroscopic analyses performed in the vacuum ultraviolet spectral range (110-300 nm) on amorphous carbon grains produced under different and controlled physical conditions and with two different production methods. The results confirm that particles similar to those obtained in the laboratory might reproduce the extinction observed toward a class of stellar sources characterized by an absorption "bump" at around 240 nm. The 220 nm interstellar hump is not reproduced by laboratory particles. However, a form of the same carbonaceous grains, partially modified in the chemical, structural, and/or morphological properties, may be used to simulate the interstellar extinction curve.