1
|
Wang XD, Robertson PA, Cascarini FJJ, Quinn MS, McManus JW, Orr-Ewing AJ. Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH 4. J Phys Chem A 2019; 123:7758-7767. [PMID: 31442046 DOI: 10.1021/acs.jpca.9b06806] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Using a combination of velocity-map imaging and resonance-enhanced multiphoton ionization detection with crossed molecular beam scattering, the dynamics of rotational energy transfer have been examined for NO in collisions with CH4 at a mean collision energy of 700 cm-1. The images of NO scattered into individual rotational (jNO') and spin-orbit (Ω) levels typically exhibit a single broad maximum that gradually shifts from the forward to the backward scattering direction with increasing rotational excitation (i.e., larger ΔjNO). The rotational rainbow angles calculated with a two-dimensional hard ellipse model show reasonable agreement with the observed angles corresponding to the maxima in the differential cross sections extracted from the images for higher ΔjNO transitions, but there are clear discrepancies for lower ΔjNO (in particular, final rotational levels with jNO' = 7.5 and 8.5). The sharply forward scattered angular distributions for these lower ΔjNO transitions better agree with the predictions of an L-type rainbow model. The more highly rotationally excited NO appears to coincide with low rotational excitation of the co-product CH4, indicating a degree of rotational product-pair anticorrelation in this bimolecular scattering.
Collapse
Affiliation(s)
- Xu-Dong Wang
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , United Kingdom
| | - Patrick A Robertson
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , United Kingdom
| | - Frederick J J Cascarini
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , United Kingdom
| | - Mitchell S Quinn
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , United Kingdom
| | - Joseph W McManus
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , United Kingdom
| | - Andrew J Orr-Ewing
- School of Chemistry , University of Bristol , Cantock's Close , Bristol , BS8 1TS , United Kingdom
| |
Collapse
|
2
|
Surin L, Schnell M. Rotational spectrum of the NH 3–He van der Waals complex. EPJ WEB OF CONFERENCES 2017. [DOI: 10.1051/epjconf/201713203045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
3
|
Luxford TFM, Sharples TR, Townsend D, McKendrick KG, Costen ML. Comparative stereodynamics in molecule-atom and molecule-molecule rotational energy transfer: NO(A(2)Σ(+)) + He and D2. J Chem Phys 2016; 145:084312. [PMID: 27586927 DOI: 10.1063/1.4961258] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a crossed molecular beam scattering study, using velocity-map ion-imaging detection, of state-to-state rotational energy transfer for NO(A(2)Σ(+)) in collisions with the kinematically identical colliders He and D2. We report differential cross sections and angle-resolved rotational angular momentum polarization moments for transfer of NO(A, v = 0, N = 0, j = 0.5) to NO(A, v = 0, N' = 3, 5-12) in collisions with He and D2 at respective average collision energies of 670 cm(-1) and 663 cm(-1). Quantum scattering calculations on a literature ab initio potential energy surface for NO(A)-He [J. Kłos et al., J. Chem. Phys. 129, 244303 (2008)] yield near-quantitative agreement with the experimental differential scattering cross sections and good agreement with the rotational polarization moments. This confirms that the Kłos et al. potential is accurate within the experimental collisional energy range. Comparison of the experimental results for NO(A) + D2 and He collisions provides information on the hitherto unknown NO(A)-D2 potential energy surface. The similarities in the measured scattering dynamics of NO(A) imply that the general form of the NO(A)-D2 potential must be similar to that calculated for NO(A)-He. A consistent trend for the rotational rainbow maximum in the differential cross sections for NO(A) + D2 to peak at more forward angles than those for NO(A) + He is consistent with the NO(A)-D2 potential being more anisotropic with respect to NO(A) orientation. No evidence is found in the experimental measurements for coincident rotational excitation of the D2, consistent with the potential having low anisotropy with respect to D2. The NO(A) + He polarization moments deviate systematically from the predictions of a hard-shell, kinematic-apse scattering model, with larger deviations as N' increases, which we attribute to the shallow gradient of the anisotropic repulsive NO(A)-He potential energy surface.
Collapse
Affiliation(s)
- Thomas F M Luxford
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Thomas R Sharples
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Dave Townsend
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - Matthew L Costen
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| |
Collapse
|
4
|
van der Avoird A, Loreau J, Alexander MH, van de Meerakker SYT, Dagdigian PJ. Resonances in rotationally inelastic scattering of NH3 and ND3 with H2. J Chem Phys 2015; 143:044312. [PMID: 26233134 DOI: 10.1063/1.4927074] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ad van der Avoird
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Jérôme Loreau
- Service de Chimie Quantique et Photophysique C. P. 160/09, Université Libre de Bruxelles (ULB), 50 Ave. F. D. Roosevelt, 1050 Brussels, Belgium
| | - Millard H. Alexander
- Department of Chemistry and Biochemistry and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742-2021, USA
| | | | - Paul J. Dagdigian
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218-2685, USA
| |
Collapse
|
5
|
Tkáč O, Saha AK, Loreau J, Ma Q, Dagdigian PJ, Parker DH, van der Avoird A, Orr-Ewing AJ. Rotationally inelastic scattering of ND3with H2as a probe of the intermolecular potential energy surface. Mol Phys 2015. [DOI: 10.1080/00268976.2015.1059958] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
6
|
Tkáč O, Saha AK, Loreau J, Parker DH, van der Avoird A, Orr-Ewing AJ. Rotationally Inelastic Scattering of Quantum-State-Selected ND3 with Ar. J Phys Chem A 2015; 119:5979-87. [PMID: 25532415 DOI: 10.1021/jp5115042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Rotationally inelastic scattering of ND3 with Ar is studied at mean collision energies of 410 and 310 cm(–1). In the experimental component of the study, ND3 molecules are prepared by supersonic expansion and subsequent hexapole state selection in the ground electronic and vibrational levels and in the jk(±) = 1(1) rotational level. A beam of state-selected ND3 molecules is crossed with a beam of Ar, and scattered ND3 molecules are detected in single final j′k′(±) quantum states using resonance enhanced multiphoton ionization spectroscopy. State-to-state differential cross sections for rotational-level changing collisions are obtained by velocity map imaging. The experimental measurements are compared with close-coupling quantum-mechanical scattering calculations performed using an ab initio potential energy surface. The computed DCSs agree well with the experimental measurements, confirming the high quality of the potential energy surface. The angular distributions are dominated by forward scattering for all measured final rotational and vibrational inversion symmetry states. This outcome is in contrast to our recent results for inelastic scattering of ND3 with He, where we observed significant amount of sideways and backward scattering for some final rotational levels of ND3. The differences between He and Ar collision partners are explained by differences in the potential energy surfaces that govern the scattering dynamics.
Collapse
Affiliation(s)
- Ondřej Tkáč
- †Laboratorium für Physikalische Chemie, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Ashim K Saha
- ‡Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 1, 6525ED Nijmegen, The Netherlands
| | - Jérôme Loreau
- §Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles (ULB) CP 160/09, 50 Av. F. D. Roosevelt, 1050 Brussels, Belgium
| | - David H Parker
- ‡Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 1, 6525ED Nijmegen, The Netherlands
| | - Ad van der Avoird
- ‡Institute for Molecules and Materials, Radboud University Nijmegen, Toernooiveld 1, 6525ED Nijmegen, The Netherlands
| | - Andrew J Orr-Ewing
- ∥School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| |
Collapse
|
7
|
Tkáč O, Ma Q, Stei M, Orr-Ewing AJ, Dagdigian PJ. Rotationally inelastic scattering of methyl radicals with Ar and N2. J Chem Phys 2015; 142:014306. [PMID: 25573560 DOI: 10.1063/1.4904901] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The rotationally inelastic scattering of methyl radical with Ar and N2 is examined at collision energies of 330 ± 25 cm(-1) and 425 ± 50 cm(-1), respectively. Differential cross sections (DCSs) were measured for different final n' rotational levels (up to n' = 5) of the methyl radicals, averaged over k' sub-levels, using a crossed molecular beam machine with velocity map imaging. For Ar as a collision partner, we present a newly constructed ab initio potential energy surface and quantum mechanical scattering calculations of state-resolved DCSs. These computed DCSs agree well with the measurements. The DCSs for both Ar and N2 collision partners are strongly forward peaked for all spectroscopic lines measured. For scattering angles below 60°, the theoretical CD3-Ar DCSs show diffraction oscillations that become less pronounced as n' increases, but these oscillations are not resolved experimentally. Comparisons are drawn with our recently reported DCSs for scattering of methyl radicals with He atoms.
Collapse
Affiliation(s)
- Ondřej Tkáč
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Qianli Ma
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218-2685, USA
| | - Martin Stei
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Andrew J Orr-Ewing
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Paul J Dagdigian
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218-2685, USA
| |
Collapse
|
8
|
Tkáč O, Rusher CA, Greaves SJ, Orr-Ewing AJ, Dagdigian PJ. Differential and integral cross sections for the rotationally inelastic scattering of methyl radicals with H2and D2. J Chem Phys 2014; 140:204318. [DOI: 10.1063/1.4879618] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|