title: Imaging the reaction dynamics of OH + CD4. 3. Isotope effects.
abstract: Isotope effects in the reaction of hydroxyl radical with methane are investigated in a crossed-beam experiment. By exploiting different combinations of OH/OD + CH4/CD4/CHD3, a total of eight isotopically variant reactions are examined to decipher the dynamical consequence of both primary and secondary isotope effects. The most prominent observation is from isotopic substitution of the transferred atom (primary isotope effect), which yields more stretch-excited water product for the D atom case than H atom. The opposite is found, however, for excitations in bending and combination modes. The secondary isotope effects, from either substituted hydroxyl radical or the three H atoms that are not being abstracted, are relatively minor and manifest themselves in spreading the vibrational distribution of the water coproducts.
authors.affiliation: Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 10617.
authors.forename: Bailin
authors.initials: B
authors.lastname: Zhang
authors.forename: Weicheng
authors.initials: W
authors.lastname: Shiu
authors.forename: Kopin
authors.initials: K
authors.lastname: Liu