THE ORIGIN OF INFRARED-ABSORPTION BANDS OF SOOT IN THE REGION 750 TO 900 CM-1

Bands which showed isotopic shifts upon regenerating soot functionalities with **1**8O//2 in the 1700 cm** minus **1 and 1200 cm** minus **1 regions were assigned to ketone-like carbonyl and ether-like groups on the surface, while the 1590 cm** minus **1 band, which fails to show any isotopic shift upon the reoxidation of soot with **1**8O//2 at high temperature, has been assigned to a carbonyl group conjugated with aromatic ring segments. Bands in the 800 cm** minus **1 were given no definite assignments. Logical origins of these bands could be the C-H out-of-plane bending of highly substituted aromatic compounds or stretching modes of peroxides or hydroperoxides. An attempt is made in this work to substantiate the origin of these bands.