Identification of the 'unidentified' IR emission features of interstellar dust?
A. Leger, J. L. Puget;
AaA, 1984, 137, L5
ABSTRACT:A consistent explanation for the so-called unidentified IR emission features of interstellar dust is proposed.
Following Sellgren (1984), the
transient heating of very small grains to a peak temperature of about 1000 K by the
absorption of a single UV photon is considered, and the subsequent IR emission is
estimated.
It is shown that graphite is one of the few solids that would not sublime
under such conditions, and that the stretching modes of the CH radicals
resulting from the conditions give an excellent fit to the observed 3.28 micron
emission band.
It is demonstrated that bulk graphite optical constants are
inadequate for small carbon clusters due to a size effect.
The expected emission
of coronene, a medium-sized polycyclic aromatic molecule, heated to an
average temperature of 600 K is computed and the spectral features are found to
be in impressive agreement with most of the observed emission bands.
KEYWORDS: cosmic dust, emission spectra, infrared spectra, interstellar chemistry, carbon, electromagnetic absorption, graphite, hydrogen, transient heating
PERSOKEY:dust, ,
CODE: leger84