Abstract: The technique of the high-temperatufe flash pyrolysis has been used for the generation of jet-cooled methyl free radical beam. The result shows that Di-tert-butyl peroxide (DTBP) starts to decompose obviously at temperature up to 900 K, and reaches the complete decomposition at 1300 K. Short contact time of the seeded precursor molecules (4% mole DTBP in He) suppresses recombination of the methyl radicals. The major fragments for the flash pyrolysis of DTBP are CH₃COCH₃and CH₃·radical.

Key words: Methyl free radical, Flash pyrolysis, Di-t-butyl peroxide