Astron. Astrophys. Suppl. Ser. 141, 149-156

Infrared spectral sequence of quenched carbonaceous composite subjected to thermal annealing

M. Goto ¹ - T. Maihara ¹ - H. Terada ¹ - C. Kaito ² - S. Kimura ² - S. Wada ³

Send offprint request: M. Goto

Correspondence to: mgoto@cr.scphys.kyoto-u.ac.jp

1 - Department of Physics, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo, Kyoto 606-8502, Japan
e-mail: mgoto@cr.scphys.kyoto-u.ac.jp
2 - Department of Physics, University of Ritsumeikan, Nojicho, Kusatsu, Shiga 525-8577, Japan
3 - Department of Chemistry, University of Electro-Communications, Chofugaoka, Chofu-shi, Tokyo 182-8585, Japan

Received August 30; accepted October 4, 1999

Abstract:

We investigate the spectroscopic alteration through thermal annealing on the quenched carbonaceous composite (QCC) produced from hydrocarbon plasma. The emission and absorption spectra of QCC samples annealed at various temperatures indicate that the proportion of aliphatic C-H bonds in QCC decreases relative to aromatic C-H bonds with increase of annealing temperature. By comparing the spectra of annealed QCC with observed emission spectra of proto-planetary nebulae, similarity between the spectral sequence obtained in the laboratory and that in the observational data is clearly noticed. On this basis, we discuss a simple evolutional scenario of carbon dust in circumstellar environment around cool evolved stars.

Key words: (stars:) circumstellar matter -- stars: individual (IRAS 05341+0852) -- stars: AGB and post-AGB -- (ISM:) dust, extinction -- infrared: ISM: lines and bands -- methods: laboratory