Role of potential structure in the collisional excitation of metastable O(1D) atoms

This paper considers the collisional excitation of O${(}^1$D) modeled by the crossing of two valence 1 ${}_{}{}^3{}_{}{}^{}\mathrm{\Pi }_{\mathit{g}}^{}{}_{}{}^{}$ curves dissociating to O${(}^3$P)+O${(}^3$P) [${\mathit{V}}_{11}$(R)] and O${(}^3$P)+O${(}^1$D) [${\mathit{V}}_{22}$(R)] which in turn are further crossed by the ${}_{}{}^3{}_{}{}^{}\mathrm{\Pi }_{\mathrm{g}}^{}{}_{}{}^{}$ Rydberg curve dissociating to O${(}^3$P)+O${(}^5$S) [${\mathit{V}}_{33}$(R)]. The role of structure in the potential curves and coupling matrix elements is quantitatively probed by the first-order functional-sensitivity densities δ ln${\mathrm{\sigma }}_{12}$(E)/δ ln${\mathit{V}}_{\mathit{i}\mathit{j}}$(R) of the excitation cross section ${\mathrm{\sigma }}_{12}$(E) obtained from close-coupling calculations. The results reveal that, in spite of the well-separated nature of the crossing between the two valence curves from their crossings with the Rydberg potential curve, the excitation cross section ${\mathrm{\sigma }}_{12}$ displays considerable sensitivity to the Rydberg curve ${\mathit{V}}_{33}$(R) at all energies in the range 3.0–9.0 eV. For relative collisional energies corresponding to the higher closely spaced vibrational energy levels of the Rydberg state, the excitation cross section is found to be much more sensitive to the Rydberg state than to the two valence states themselves.