The primary goal of the present study was to map out the changes in reaction mechanism as the collision energy is varied from 0.4 eV to 0.15 eV for the SN2 reaction
Cl- + CH3I→ClCH3 + I- in gas phase.
Probability of direct versus indirect mechanism at different collisional energies for impact parameter b = 0. Data points: green squares: fraction of direct product channels; red circles: fraction of indirect product channels. Error bars are calculated for each data point. Dotted lines represent best fitted curves.
Distribution of velocity scattering angles (cos θ) of products at two different collisional energies, e. g. 0.40 eV at impact parameter b=0; 0.15, 0.25 and 0.40 eV at impact parameter b = 1