FLASH PYROLYSIS NOZZLE FOR GENERATION OF RADICALS IN A SUPERSONIC JET EXPANSION

A method for the high-temperature generation of reactive species in supersonic molecular beams has been developed. Pyrolysis temperatures (25-1800-degrees-C) can be maintained for longer than 100 h for extended experiments. Short contact time (almost-equal-to 10-mu-s) of the seeded (< 1 Torr partial pressure in 2 atm inert carrier gas) precursor molecules suppresses recombination of the product radicals. Number densities for radicals are estimated to be almost-equal-to 10(14) cm-3 at the sonic orifice with radical fluxes of almost-equal-to 10(16) s-1.