REACTIONS OF N(2 D-2) WITH METHANE AND DEUTERATED METHANES

NH radicals and H atoms were identified as products in the reaction of N(D-2) with CH4. The absolute yields of NH and H were determined to b e 0.3+/-0.1 and 0.8+/-0.2, respectively. The rotational state distribu tions of NH (upsilon''=0) for CH4 and partially deuterated methanes, C HnD4-n (n = 1-3), are single modal and peak at N''=13+/-2, while the v ibrational population ratios, NH (upsilon''=1)/NH (upsilon''=0), are 0 .6. The rotational energy distribution of ND (upsilon''=0) from CD, is similar to that for NH (upsilon''=0). The ND (upsilon''=1)/ND (upsilo n''=0) ratio is 0.6. Doppler profiles of H and D atoms were measured t o evaluate the energy released to the translational mode. it was betwe en 72 and 85 kJ mol(-1), suggesting the following H atom product-ion m echanism: N(D-2)+CH4-->H+CH2NH. The H+CH3N channel is minor. In the re actions with partially deuterated methanes, the isotopic ratios, [H]/[ D] and [NH]/[ND], are larger than the stoichiometric ratios in the rea ctant methanes. These results suggest that C-H bonds are more reactive to N(D-2) than C-D bonds, while H atoms are ejected more preferential ly than D atoms. (C) 1998 American Institute of Physics.