ABSOLUTE REACTIVE CROSS-SECTION FOR H-ATOM FORMATION IN THE REACTION OF TRANSLATIONALLY ENERGETIC O(D-1) ATOMS WITH METHANE

The dynamics of the H atom formation channel in the reaction of metast able oxygen atoms O(D-1) with methane were studied in the gas phase us ing the pulsed laser photolysis/vacuum-UV laser-induced fluorescence ' 'pump-and-probe'' technique. Translationally energetic O(D-1) atoms wi th an average collision energy of 37 kJ/mol in the O(D-1)-CH4 center-o f-mass system were generated by laser photolysis of N2O at 193 nm. Nas cent H atoms produced in reactive collisions of O(D-1) with room-tempe rature CH4 molecules were detected with sub-Doppler resolution via (2p (2)P - 1s(2)S) laser-induced fluorescence. An absolute reaction cross section of sigma(H)(37 kJ/mol) = 1.4 +/- 0.5 Angstrom(2) was determine d for the H atom formation channel by means of a calibration method. F rom the Il atom Doppler profiles measured under single-collision condi tions the product translational energy release was determined.