ON THE ROLE OF POTENTIAL FEATURES IN FINE-STRUCTURE TRANSITIONS WITH APPLICATION TO H-2(1(+F(P)2))-]H++F(P-2(3/2))/

The first order functional sensitivity densities delta In sigma(1/2--> 3/2)(E)/delta ln W-\A\(R) are employed to assess the role of structure in potential energy curves W-0(R) and W-0(R) involved in the fine-str ucture transition H+ + F(P-2(1/2))-->H+ + F(P-2(3/2)). The results rev eal that the fine-structure transition cross-section draws on the W-0( (2) Sigma) and W-1((2) Pi) potentials in a highly correlated fashion a nd a measurement of sigma 1/2-->3/2(E) for H+ + F will primarily allow information to be extracted only on the potential function difference W-0(R) - W-1(R) for moderate to large internuclear distances (R great er than or similar to 3 a(0)). While there is a marginal preference fo r the pi alignment in the region where splitting between the (2) Pi an d (2) Sigma curves is equal to the fine-structure transition energy, t he oscillatory nature of the sensitivity densities with respect to R i ndicates that the alignment effects may disappear upon averaging over many impact parameters. The results from both functional sensitivity a nd adiabatic analysis isolate the region of potential energy curves ce ntered at R approximate to 7.8 a(0) where the potential function diffe rence W-0(R) - W-1(R) is equal to the fine-structure splitting, to be of maximum significance to the collisional fine-structure transition i n this system.