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. 2016 Jan 1;7(1):642-649.
doi: 10.1039/c5sc03373j. Epub 2015 Oct 5.

Effects of Reagent Rotation on Interferences in the Product Angular Distributions of Chemical Reactions

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Free PMC article

Effects of Reagent Rotation on Interferences in the Product Angular Distributions of Chemical Reactions

P G Jambrina et al. Chem Sci. .
Free PMC article

Erratum in

Abstract

Differential cross sections (DSCs) of the HD(v', j') product for the reaction of H atoms with supersonically cooled D2 molecules in a small number of initial rotational states have been measured at a collision energy of 1.97 eV. These DCSs show an oscillatory pattern that results from interferences caused by different dynamical scattering mechanisms leading to products scattered into the same solid angle. The interferences depend on the initial rotational state j of the D2(v = 0, j) reagent and diminish in strength with increasing rotation. We present here a detailed explanation for this behavior and how each dynamical scattering mechanism has a dependence on the helicity Ω, the projection of the initial rotational angular momentum j of the D2 reagent on the approach direction. Each helicity corresponds to a different internuclear axis distribution, with the consequence that the dependence on Ω reveals the preference of the different quasiclassical mechanisms as a function of approach direction. We believe that these results are general and will appear in any reaction for which several mechanisms are operative.

Figures

Fig. 1
Fig. 1. Comparison between the experimental angular distributions (blue solid circles) and their theoretically simulated counterparts (continuous black line) for four HD(v′, j′) rovibrational states at 1.97 eV mean collision energy. The simulation implies the averaging of the differential cross sections (multiplied by sin θ) over the experimental collision energy distribution and angular resolution. The simulation also implies consideration of the weighted contributions from the reaction with D2 in the rotational states populated under the experimental conditions. The corresponding contributions are indicated in each panel by the red line (j = 0), the blue line (j = 1) and the green line (j = 2) such that their sum yields the black line.
Fig. 2
Fig. 2. Angular distributions and deflection functions for the H + D2(v = 0, j = 0–2) → D + HD(v′ = 1, j′ = 0) reaction at 1.97 eV collision energy. The top panels show the QM angular distributions for the three rotational states populated in the experiment. The bottom panel shows the state-to-state quasiclassical deflection functions, D r(J, θ). Although the oscillation pattern is clearly affected by the initial rotational state, the QCT deflection functions are remarkably similar. The quasiclassical mechanisms are labelled in the figure as 1 (ear), 2, 3, 3′ and 4 (the last three form the spiral)., The spiral mechanism displays a clear correlation between J and θ that extends over the whole range of scattering angles. The sketches of the mechanisms that correspond to the labelled regions of D r(J, θ) are displayed in Fig. S1, ESI.
Fig. 3
Fig. 3. QM DCS(|Ω|) for the H + D2(v = 0, j = 1 and 2) → D + HD(v′ = 1, j′) reactions. The interference pattern, partially blurred as j increases, clearly reappears when the contributions due to the different |v, j, Ω states are separated.
Fig. 4
Fig. 4. Origin of multiple peaks in backward scattering of HD(v′ = 1, j′ = 0, Ω) products for initial j = 2. The top panels show the joint QCT Jθ deflection function resolved in Ω, (2J + 1) P r(J, θ; Ω) sin θ, analogous to that displayed in panel (b) of Fig. 1. The bottom panels show the decomposition of the QM angular distributions from the contributions of various sets of J. The notation DCS(J 1J 2) means that the DCS is constructed by including partial waves in the range [J 1, J 2] including the respective cross terms. The global DCS(|Ω|) is depicted as a shaded background.
Fig. 5
Fig. 5. QM DCS(|Ω|) and angular distributions and deflection functions for the H + D2(j = 0–2) → D + HD(v′ = 3, j′ = 0) reaction.

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References

    1. Crease R. P. Phys. World. 2002;15:15–17.
    1. Jöhnsson C. Z. Phys. 1961;161:454.
    1. Steeds P. G. M. J., Pozzi G., Missiroli G. F., Tonomura A. Phys. World. 2003;16:20–21.
    1. Carnal O., Mlynek J. Phys. Rev. Lett. 1991;66:2689–2692. - PubMed
    1. Arndt M., Nairz O., Vos-Andreae J., Keller C., van der Zouw G., Zeilinger A. Nature. 1999;401:680–682. - PubMed
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