Infrared spectrum of quenched carbonaceous composite (QCC). II - A new identification of the 7.7 and 8.6 micron unidentified infrared emission bands

Abstract

Infrared spectrum of 'oxidized' quenched carbonaceous composite (QCC) is presented. In addition to the features seen in 'unoxidized' QCC, new features appear at 7.7 and 8.6 microns and the strengths of the features at 6.2, 7.3, and 11.4 microns increase. The infrared features of 'oxidized' QCC are in good agreement with nine of 11 members of the unidentified infrared (UIR) emission bands. The absorption bands of QCC are all broad without fine structure, clearly different from sharp bands of molecules. The 7.7 and 8.6 micron features can be attributed to a 'cross-conjugated ketone' molecular structure. A possible identification of the UIR 7.7 and 8.6 micron bands with this structure is discussed. The present results indicate that oxygen can play an important role in the structures of the UIR emitting material as well as carbon and hydrogen.