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

The photoloc technique with core extraction of the nascent product laborato ry speed distribution in a Wiley-McLaren time-of-flight spectrometer has be en used to measure differential cross sections for the reaction H+D-2--> HD (v(')=2, J(')=0,3,5)+D at collision energies similar to 1.55 eV. We find t hat the peak of each angular distribution shifts from complete backward sca ttering 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 similar to 1.70 eV. We conclude that the same type o f 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 o f 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 elast ic specular scattering, this result implies that smaller impact parameters lead to more vibrationally excited products. (C) 1999 American Institute of Physics. [S0021-9606(99)01130-7].