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Interference structures in the differential cross-sections for inelastic scattering of NO by Ar


Inelastic scattering is a fundamental collisional process that plays an important role in many areas of chemistry, and its detailed study can provide valuable insight into more complex chemical systems. Here, we report the measurement of differential cross-sections for the rotationally inelastic scattering of NO(X2Π1/2, v = 0, j = 0.5, f) by Ar at a collision energy of 530 cm−1 in unprecedented detail, with full Λ-doublet (hence total NO parity) resolution in both the initial and final rotational quantum states. The observed differential cross-sections depend sensitively on the change in total NO parity on collision. Differential cross-sections for total parity-conserving and changing collisions have distinct, novel quantum-mechanical interference structures, reflecting different sensitivities to specific homonuclear and heteronuclear terms in the interaction potential. The experimental data agree remarkably well with rigorous quantum-mechanical scattering calculations, and reveal the role played by total parity in acting as a potential energy landscape filter.

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Figure 1: Experimental and fitted ion images.
Figure 2: Experimental versus quantum-mechanically calculated DCSs.
Figure 3: An illustration of the blurring effect of averaging over the initial NO Λ-doublet states.
Figure 4: Illustration of the four limiting paths used in the hard shell calculations.
Figure 5: Comparison of DCSs from the hard shell model with those from CC QM and QQT theory.


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Support was provided by the UK EPSRC (to M.B. via programme grant no. EP/G00224X/1), the EU (to M.B. via FP7 EU People ITN project 238671), Consolider Ingenio 2010 (grant CSD2009-00038) and the Spanish Ministry of Science and Innovation (grant CTQ2008-02578/BQU). J.K. acknowledges financial support from the US National Science Foundation (grant no. CHE-0848110 to M.H. Alexander (Department of Chemistry and Biochemistry, University of Maryland, USA)) and the University Complutense de Madrid/Grupo Santander (under the ‘Movilidad de Investigadores Extranjeros’ programme). The support of the LASERLAB EUROPE is also gratefully acknowledged. Finally, the authors thank D.H. Parker and G. McBane for valuable discussions, and A. Ballast for help with collecting some of the data reported here.

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The research project was conceived by M.B., F.J.A. and S.S., and the experiments were performed by C.J.E., C.-H.Y., A.G., A.E.W. and S.S. Calculations were performed by C.J.E., A.G., J.K., F.J.A. and S.S., and the paper was written by M.B. and C.J.E. All authors contributed to discussions about the content of the paper.

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Correspondence to M. Brouard.

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Eyles, C., Brouard, M., Yang, CH. et al. Interference structures in the differential cross-sections for inelastic scattering of NO by Ar. Nature Chem 3, 597–602 (2011).

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