Adiabatic and Nonadiabatic Effects in the Transition States of State to State Autoionization Processes

General treatment for stereo-dynamics of state-to-state chemi-ionization reactions

“…Such results suggest that at short distances, where the molecular Λ character is more pronounced, the coupling terms A Σ-Σ and A Π-Π become dominant, while at long range, where the molecular character is mixed by SO and other electronic arrangements operate, the indirect couplings terms, A Σ-Π and A Π-Σ , become prevalent in determining the Γ strength. Therefore, the electronic mechanisms, which drive the reaction at small and high collision energy, appear to vary substantially being preferentially triggered in the different ranges of probed R. Moreover, the Γ term, evaluated in previous studies and showing only a radial dependence 45 , must be related to the weighted average of state-to-state Γ components 27,28 .…”

“…On this ground, two different and complementary mechanisms have been also recently proposed 27,28 , that are so classified:…”

“…Therefore, the indirect mechanism contributions also include presumably possible contributions from radiative effects 44,45 generated by metastable atomic states perturbed within the weakly interacting complex. This mechanism involves two possible coupling terms, A Σ-Π and A Π-Σ , identified again on the basis of the symmetry of the initial and final states and exhibiting a less pronounced dependence on R respect to A Σ-Σ and A Π-Π 27,28 .…”

“…All experimental data, investigated in this paper, have been measured in gas phase with the molecular beam (MB) technique applied under single collision and high resolution conditions 8,[30][31][32][33][34] . A schematic view of MB apparatus available in our laboratory and extensively described elsewhere 27,28,35 , is given in the Supplementary Methods and Supplementary Fig. 1.…”

“…Moreover, the imaginary part formulation is fully discussed in the previous section (see, in particular, Eqs. [22][23][24][25][26][27][28][29][30][31][32][33]. Points represent peak area ratios with their relative error bars extracted from the analysis of Ne * -Kr PIESs measured as a function of the collision energy, where the contributions of four reaction channels, associated to two different spin-orbit states J of Ne * neutral reactant (J i = 2, 0) and of Kr + ( 2 P J ) ionic product (J f = 3/2, 1/2), have been resolved (see text and Supplementary Fig.…”