Differential cross sections for H + D_2 -> HD (v' = 2,J' = 0,3,5) + D at 1.55 eV

摘要

The photoloc technique with core extraction of the nascent product laboratory speed distribution in a Wiley-McLaren time-of-flight spectrometer has been used to measure differential cross sections for the reaction H + D_2 -> HD (v' = 2,J' = 0,3,5) + D at collision energies approx 1.55 eV. We find that the peak of each angular distribution shifts from complete backward scattering toward side scattering as the rotational excitation of the product increases. We found the same trend in our previous study of H + D_2 -> HD (v' = 1,J' = 1,5,8) + D at approx 1.70 eV. We conclude that the same type of correlation exists between impact parameter and rotational quantum number in both product vibrational manifolds. Further analysis of the HD (v' = 2,J') differential cross section data reveals, however, a clear tendency of this vibrational manifold to scatter sideways at lower J' than HD(v' = 1,J'). Within the framework of a line-of-centers model with nearly elastic specular scattering, this result implies that smaller impact parameters lead to more vibrationally excited products.