The first-order functional sensitivity densities δ ln${\mathrm{\sigma }}_{1/2\to 3/2}$(E)/δ ln${\mathit{W}}_{\mathrm{\Vert }\mathrm{\Lambda }\mathrm{\Vert }}$(R) are employed to assess the role of structure in the potential-energy curves ${\mathit{W}}_0$${(}^2$Σ) and ${\mathit{W}}_1$${(}^2$Π) mediating the fine-structure transition Na${(}^2$${\mathit{P}}_{1/2}$)+He→Na${(}^2$${\mathit{P}}_{3/2}$)+He and Na${(}^2$${\mathit{P}}_{1/2}$)+Ar→Na${(}^2$${\mathit{P}}_{3/2}$)+Ar. The sensitivity density profiles δ ln${\mathrm{\sigma }}_{1/2\to 3/2}$(E)/δ ln${\mathit{W}}_{\mathrm{\Vert }\mathrm{\Lambda }\mathrm{\Vert }}$(R) for the two systems reveal that regions of significance differ widely for the ${}_{}{}^2{}_{}{}^{}\mathrm{\Sigma }$ and ${}_{}{}^2{}_{}{}^{}\mathrm{\Pi }$ curves. The results suggest that prevalent mechanistic explanations from adiabatic analyses have limitations in terms of the ultimate significance of the identified kinematic coupling over well demarcated radial and angular coupling regions. The functional sensitivity analysis is shown to permit a full deconvolution of the collision cross section’s dependence on the features in the individual ${}_{}{}^2{}_{}{}^{}\mathrm{\Sigma }$ and ${}_{}{}^2{}_{}{}^{}\mathrm{\Pi }$ curves as opposed to the adiabatic analysis where only the features in [${\mathit{W}}_0$(R)-${\mathit{W}}_1$(R)] are deemed critical to the collisional outcome.

• Received 31 March 1994

DOI:https://doi.org/10.1103/PhysRevA.50.3142