The methyl radical combination rate constant as determined by kinetic spectroscopy

The rate constant for the reaction has been determined by means of vacuum ultraviolet flash photolysis and time‐resolved kinetic spectroscopic observations of the 1504‐Å absorption band of CH3. The measurements made using three different sources of methyl radicals (azomethane, dimethylmercury, and ketene‐hydrogen) were in accord and yielded a value for the rate constant of k1 = (9.53 ± 1.17) × 10−11 cc molec−1 sec−1. A detailed error analysis is presented. The f‐value for the 1504‐Å band of CH3 is determined to be (2.5 ± 0.7) × 10−2.