Detailed Energy Dependences of Cross Sections and Rotational Distributions for the Ne + H₂⁺ → NeH⁺ + H Reaction

Abstract

Detailed energy dependences of state-to-state and state-to-all integral cross sections have been studied by means of exact three-dimensional hyperspherical calculations, for the complex-forming Ne + H 2 + f NeH + + H reaction. Integral cross sections show an outstandingly marked structure as a function of energy. This structure has been characterized analyzing the state-to-state contributions, on one hand, and the partial cross section cumulative sums as a function of the total angular momentum quantum number J, on the other. As expected, the key fact is that strongly bound metastable states lead to peaks in the above quantities narrow enough to avoid an effective quenching of the resulting structure, when summing either over J or over final product states. This feature, which has already been found for other complex-forming reactions, indicates that quantum effects can be more relevant than expected, so as to require their explicit consideration when accurately characterizing a reactive event. Additionally, the implications of the observed behavior for the J-shifting approximation have been analyzed. In particular, it is shown how a clear J-shifting behavior is found for low J, Ω ) 0. However, it is lost as higher J values are considered (for Ω ) 0) or, as it is wellknown, higher Ω projections are included in the calculation. A rationale for this behavior is presented.

A pulsed-field ionization photoelectron secondary ion coincidence study of the H2+(X,υ+=–15,N+=1)+He proton transfer reaction

“…3 In our investigation of the H 2 + + Ne proton transfer system 3 we succeeded in measuring an absolute integral reaction cross section for H 2 + populated in the + = 17, N + = 1 rovibrational level which lies merely 0.03 eV below the dissociation limit. [5][6][7] The calculated cross sections for + Ͼ 0 at low total energies ͑E Ͻ 1 eV͒ were significantly higher than the measured values, suggesting a possible overemphasis of resonances in the theoretical work which again may be attributed to an inaccurate potential. Discrepancies at low total energies were attributed to resonances, which had been observed in numerous quantum scattering studies, 4-7 while at high energies, it was suggested that possibly nonadiabatic effects, or inaccuracies in the applied potential, 8 could explain that QCT appeared to overpredict the competitive effect of the collision-induced dissociation ͑CID͒ channel.…”

Quantum scattering calculation of the O(1D)+HBr reaction

“…Quantum calculation of reactions proceeding without a potential barrier, and typically by complex formation, are very demanding, due both to the presence of a complex region, which causes the wave function oscillate rapidly, and also to the large region of configuration space that is accessible to the reaction. Previous, full dimensionality quantum calculations of such reactions have been reported for HϩO 2 , [22][23][24][25] 26,27 NϩH 2 , 28 and the ion-molecule reaction N ϩ ϩH 2 , 29 Ne ϩH 2 ϩ , 30 H ϩ ϩH 2 , 31,32 and He ϩ ϩH 2 . 33 So this O( 1 D) ϩHBr reaction is especially demanding, and also interesting due to the presence of two products channels.…”

Isotopic effects on the stereodynamics for the reactions

“…State-selected integral cross sections as a function of energy using the coupled-states approximation were reported by Gilibert and co-workers [3,4]. Huarte-Larrañaga et al [5,6] determined the energy dependence of the state-to-state and state-to-all integral cross section using the exact close-coupling hyperspherical. Mayneris et al [7] determined the Ne þ H þ 2 = Ne þ HD þ =Ne þ HT þ reaction probabilities and cross sections over a wide range of collision energy intervals using a time-dependent real-wave-packet (RWP) quantum calculation.…”