Sign of the state-to-state steric asymmetry of rotationally inelastic atom–molecule collisions

Gijsbertsen, A.; Lange, M.J.L. de; Wiskerke, A.E.; Linnartz, H.; Drabbels, Marcel; Kłos, Jacek; Stolte, S.

doi:10.1016/j.chemphys.2004.02.003

Cited by 15 publications

(21 citation statements)

References 33 publications

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“…The calculated integral cross sections from these scattering amplitudes for collisions of oriented NO molecules are used to define the steric asymmetry for the transition from initial state i to final state f: 23,24 S i→ f ϭ He→NO Ϫ He→ON He→NO ϩ He→ON . ͑9͒…”

Section: ͑7͒mentioning

confidence: 99%

“…The comparison of the sign of the experimental steric effect with calculated steric effects remains somewhat open to question. 24 The sign of the experimental steric effect SA is fixed by directly measuring the applied voltages and spectroscopically establishing that the low-field seeking ⌳-doublet state is preserved in the scattering center. 24 The sign of the steric asymmetry S i→ f in the calculations depends on the definition of the coordi- nates of the collision frame.…”

Section: B Steric Effects and ⌳-Doublet Propensities For F 1 \F 1 Trmentioning

confidence: 99%

“…[19][20][21] The steric asymmetry for spin-orbit conserving scattering of NO-Ar shows striking oscillations with ⌬ j; for ⌬ j even, collisions with the N end of the molecule are preferred, and for ⌬ j odd, collisions with the O end are more effective. 5,6 Although it is reproduced in quantum scattering calculations 5,22,23 ͑to within the overall sign of the effect 24 ͒, there is at present no simple physical picture of the source of this alternation. Examination of the T-matrix description of the collision process shows that the difference between scattering from the N and O end of the molecule is dependent on interference terms between transitions from e and f initial ⌳-doublet levels.…”

Section: Introductionmentioning

confidence: 99%

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Steric asymmetry and lambda-doublet propensities in state-to-state rotationally inelastic scattering of NO(2Π1/2) with He

Lange

Stolte

Taatjes

et al. 2004

The Journal of Chemical Physics

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Relative integrated cross sections are measured for rotationally inelastic scattering of NO(2Pi(1/2)),hexapole selected in the upper lambda-doublet level of the ground rotational state (j = 0.5), in collisions with He at a nominal energy of 514 cm(-1). Application of a static electric field E in the scattering region, directed parallel or antiparallel to the relative velocity vector v, allows the state-selected NO molecule to be oriented with either the N end or the O end towards the incoming He atom. Laser-induced fluorescence detection of the final state of the NO molecule is used to determine the experimental steric asymmetry, [formula: see text], which is equal to within a factor of (- 1) to the molecular steric effect, S(i-->f) is identical with (sigma(He-->NO) - (sigma(He-->ON))/(sigma(He-->NO) + sigma(He-->ON)). The dependence of the integral inelastic cross section on the incoming lambda-doublet component is also observed as a function of the final rotational (j'), spin-orbit (omega'), and lambda-doublet (epsilon') state. The measured steric asymmetries are significantly larger than previously observed for NO-Ar scattering, supporting earlier proposals that the repulsive part of the interaction potential is responsible for the steric asymmetry. In contrast to the case of scattering with Ar, the steric asymmetry of NO-He collisions is not very sensitive to the value of omega'. However, the lambda-doublet propensities are very different for [omega=0.5(F1)-->omega'= 1.5(F2)] and [omega=0.5(F1)-->omega'=0.5(F1)] transitions. Spin-orbit manifold conserving collisions exhibit a propensity for parity conservation at low deltaj, but spin-orbit manifold changing collisions do not show this propensity. In conjunction with the experiments, state-to-state cross sections for scattering of oriented NO(2Pi) molecules with He atoms are predicted from close-coupling calculations on restricted coupled-cluster methods including single, double, and noniterated triple excitations [J. Klos, G. Chalasinski, M. T. Berry, R.Bukowski, and S. M. Cybulski, J. Chem. Phys. 112, 2195 (2000)] and correlated electron-pair approximation [M. Yang and M. H. Alexander, J. Chem. Phys. 103, 6973 (1995)] potential energy surfaces. The calculated steric asymmetry S(i-->f) of the inelastic cross sections at Etr= 514 cm(-1) is in reasonable agreement with that derived from the present experimental measurements for both spin-manifold conserving (F1-->Fl) and spin-manifold changing (F1 --F2) collisions, except that the overall sign of the effect is opposite. Additionally, calculated field-free integral cross sections for collisions at Etr = 508 cm(-1) are compared to the experimental data of Joswig et al. [J. Chem. Phys.85, 1904 (1986)]. Finally, the calculated differential cross section for collision energy Etr= 491 cm(-1) is compared to experimental data of Westley et al. [J. Chem. Phys. 114, 2669 (2001)] for the spin-orbit conserving transition F1 (j = 0.5) -F1f (j' = 3.5).

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Section: ͑7͒mentioning

confidence: 99%

Section: B Steric Effects and ⌳-Doublet Propensities For F 1 \F 1 Trmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Steric asymmetry and lambda-doublet propensities in state-to-state rotationally inelastic scattering of NO(2Π1/2) with He

Lange

Stolte

Taatjes

et al. 2004

The Journal of Chemical Physics

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“…The methodology of scattering of the structureless partner with an open shell diatomic was described in detail before. 4,21,27,[32][33][34][35][36] We refer the reader to these references for details. The close-coupling calculations at a collision energy E col = 508.13 cm −1 employed all partial waves up to a total angular momentum quantum number J max = 101.5 and NO rotational levels up to jЈ = 17.5.…”

Section: Close-coupling Calculations Of Differential Cross Sectionsmentioning

confidence: 99%

Differential cross sections for collisions of hexapole state-selected NO with He

Gijsbertsen

Linnartz

Rus

et al. 2005

The Journal of Chemical Physics

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The first measurements of differential inelastic collision cross sections of fully state-selected NO ͑j =1/2, ⍀ =1/2, ⑀ =−1͒ with He are presented. Full state selection is achieved by a 2 m long hexapole, which allows for a systematic study of the effect of parity conservation and breaking on the differential cross section. The collisionally excited NO molecules are detected using a resonant ͑1+1Ј͒ REMPI ionization scheme in combination with the velocity-mapped, ion-imaging technique. The current experimental configuration minimizes the contribution of noncolliding NO molecules in other rotational states j , ⍀ , ⑀ -that contaminates images-and allows for study of the collision process at an unprecedented level of detail. A simple method to correct ion images for collision-induced alignment is presented as well and its performance is demonstrated. The present results show a significant difference between differential cross sections for scattering into the upper and lower component of the ⌳-doublet of NO. This result cannot be due to the energy splitting between these components.

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“…Using the directly measured orientation of the applied static field and the sign of the dipole moment from ab initio calculations, N δ-O δ+ , 14 and assuming no long-range collision-induced reorientation would yield SA = S iff in eq 1. As discussed elsewhere, 9,11,12,20 this assignment results in a disagreement of a factor of -1 between theory and experiment.…”

Section: Experimentmentioning

confidence: 87%

Measurements and Quasi-Quantum Modeling of the Steric Asymmetry and Parity Propensities in State-to-State Rotationally Inelastic Scattering of NO (²Π_1/2) with D₂

et al. 2007

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Relative integrated cross sections are measured for spin-orbit-conserving, rotationally inelastic scattering of NO (2Pi1/2), hexapole-selected in the upper Lambda-doublet level of the ground rotational state (j = 0.5), in collisions with D2 at a nominal energy of 551 cm-1. The final state of the NO molecule is detected by laser-induced fluorescence (LIF). The state-selected NO molecule is oriented with either the N end or the O end toward the incoming D2 molecule by application of a static electric field E in the scattering region. This field is directed parallel or antiparallel to the relative velocity vector v. Comparison of signals taken for the different applied field directions gives the experimental steric asymmetry SA, defined by SA = (sigma v upward arrow downward arrow E - sigma v upward arrow upward arrow E)/(sigma v upward arrow downward arrow E + sigma v upward arrow upward arrow E), which is equal to within a factor of -1 to the molecular steric effect, Si-->f identical with (sigmaD2-->NO - sigmaD2-->ON)/(sigmaD2-->NO + sigmaD2-->ON). The dependence of the integral inelastic cross section on the incoming Lambda-doublet component is also measured as a function of the final rotational (jfinal) and Lambda-doublet (epsilonfinal) state. The measured steric asymmetries are similar to those previously observed for NO-He scattering. Spin-orbit manifold-conserving collisions exhibit a larger propensity for parity conservation than their NO-He counterparts. The results are interpreted in the context of the recently developed quasi-quantum treatment (QQT) of rotationally inelastic scattering [Gijsbertsen, A.; Linnartz, H.; Taatjes, C. A.; Stolte, S. J. Am. Chem. Soc. 2006, 128, 8777]. The QQT predictions can be inverted to obtain a fitted hard-shell potential that reproduces the experimental steric asymmetry; this fitted potential gives an empirical estimate of the anisotropy of the repulsive interaction between NO and D2. QQT computation of the differential cross section using this simple model potential shows reasonable agreement with the measured differential cross sections.

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Sign of the state-to-state steric asymmetry of rotationally inelastic atom–molecule collisions

Cited by 15 publications

References 33 publications

Steric asymmetry and lambda-doublet propensities in state-to-state rotationally inelastic scattering of NO(2Π1/2) with He

Steric asymmetry and lambda-doublet propensities in state-to-state rotationally inelastic scattering of NO(2Π1/2) with He

Differential cross sections for collisions of hexapole state-selected NO with He

Measurements and Quasi-Quantum Modeling of the Steric Asymmetry and Parity Propensities in State-to-State Rotationally Inelastic Scattering of NO (²Π_1/2) with D₂

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Sign of the state-to-state steric asymmetry of rotationally inelastic atom–molecule collisions

Cited by 15 publications

References 33 publications

Steric asymmetry and lambda-doublet propensities in state-to-state rotationally inelastic scattering of NO(2Π1/2) with He

Steric asymmetry and lambda-doublet propensities in state-to-state rotationally inelastic scattering of NO(2Π1/2) with He

Differential cross sections for collisions of hexapole state-selected NO with He

Measurements and Quasi-Quantum Modeling of the Steric Asymmetry and Parity Propensities in State-to-State Rotationally Inelastic Scattering of NO (2Π1/2) with D2

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Measurements and Quasi-Quantum Modeling of the Steric Asymmetry and Parity Propensities in State-to-State Rotationally Inelastic Scattering of NO (²Π_1/2) with D₂