Graphene Molecule Compared With Fullerene C60 As Circumstellar Carbon
  Dust Of Planetary Nebula
  It had been understood that astronomically observed infrared spectrum of
carbon rich planetary nebula as like Tc 1 and Lin 49 comes from fullerene
(C60). Also, it is well known that graphene is a raw material for synthesizing
fullerene. This study seeks some capability of graphene based on the
quantum-chemical DFT calculation. It was demonstrated that graphene plays major
role rather than fullerene. We applied two astrophysical conditions, which are
void creation by high speed proton and photo-ionization by the central star.
Model molecule was ionized void-graphene (C23) having one carbon pentagon
combined with hexagons. By molecular vibrational analysis, we could reproduce
six major bands from 6 to 9 micrometer, large peak at 12.8, and largest peak at
19.0. Also, many minor bands could be reproduced from 6 to 38 micrometer. Also,
deeply void induced molecules (C22) and (C21) could support observed bands.
