Abstract: By means of the spin trapping-ESR technique, the influence of the tube diameters and moisture content in the sample on the radicals produced in the microwave discharge of fatty ether at low pressure has been studied systematically. The results show that:the smaller the diameter of the tube, the faster the formative speed of carbon black, as well as the shorter the lifetime of H atom. With the increase of moisture content, the extent of carbonization becomes more serious. According to the mechanism of discharge, the reasons of the carbonization are discussed.

Key words: Spin trapping, ESR, Microwave discharge, Free radical