Quantum-state distributions for the HD product of the direct reaction of H(D)/Cu(111) with D(H) incident from the gas phase

We have determined the internal-state distribution for the HD product of the reaction of gas-phase D atoms with H atoms chemisorbed on Cu(111) and for the corresponding reaction of H atoms with chemisorbed D atoms. In the case of D-on-H, the populations of the vibrational states ν = 0, 1,2, and 3 are comparable, while that for ν = 4 is considerably smaller, giving a mean vibrational energy of ∼0.7 eV. The vibrational state distribution for H-on-D is similar, but in this case there is a clear peak at ν = 1, even less population in ν = 4, and a somewhat smaller mean vibrational energy of ∼0.6 eV. The mean rotational energy falls with increasing ν in both cases, ∼0.5 eV for ν = 0 to <0.2 eV for ν = 4, with an overall mean rotational energy of ∼0.4 eV. The rotational distributions are distinctly narrower for H-on-D than for D-on-H. The maximum internal energy observed is ∼2.3 eV, consistent with the total energy available to the product. Results are consistent with recent calculations. © 1996 American Institute of Physics.