Infrared spectral sequence of quenched carbonaceous composite subjected to thermal annealing

¹ Department of Physics, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo, Kyoto 606-8502, Japan
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

Send offprint request to: M. Goto

Received: 30 August 1999
Accepted: 4 October 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.