G. Pascoli et J. Leclercq, SOME THEORETICAL CONSIDERATIONS ABOUT THE ORIGIN OF THE 220 NM INTERSTELLAR HUMP, Astrophysics and space science, 235(2), 1996, pp. 233-243
The density of state (sigma and pi) of a small graphite-like planar cl
uster is computed using a tight binding approach. We point out a possi
ble correlation between the presence of surface levels, dependent on t
he cluster size and localized near the middle of the sigma band gap, a
nd the origin of the 220 nm interstellar hump. The influence of sp(3)
sites - or impurities - randomly distributed throughout the cluster, i
s also discussed.