INTRAMOLECULAR ENERGY RELAXATION. BUTYL RADICAL DECOMPOSITION AT HIGH RESSURE,

A study of the gas phase decomposition of chemically activated 2-butyl radicals, produced by addition of H atoms to cis-butene-2, has been made over a wide range of pressures at 304 K. Together with earlier work below 5 mm at 300 K, the study of this reaction now embraces the range 0.0016 mm to 115 atm. The observed rate constant for decomposition is invariant within experimental error over the range 0.036-115 atm. The assumption of radomization of internal energy, common to the RRK and RRKM theories of unimolecular reactions, is strongly validated by the present results for complex molecules on a time scale of about 10 to the -13th power sec. Reasons are discussed why the assumption may hold for small molecules also. It appears that the RRKM treatment may be applied as a working theory to all polyatomic molecules under virtually all experimental conditions that might be encountered for ground electronic state species. Author