1
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Zhang G, Lu D, Cheng M, Guo H, Gao H. Frustrated charge transfer in vibrationally inelastic Ar ++N 2 collisions via hard collision glory scattering. Nat Commun 2024; 15:8177. [PMID: 39289362 PMCID: PMC11408667 DOI: 10.1038/s41467-024-52530-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2024] [Accepted: 09/10/2024] [Indexed: 09/19/2024] Open
Abstract
Vibrational energy transfer in collisions between ions and neutrals is a fundamental process in interstellar media, planetary atmospheres, and plasmas. The conventional wisdom is that glancing collisions with large impact parameters are forward-scattered with low vibrational excitation, while hard collisions with small impact parameters are sideway- or backward-scattered with relatively high vibrational excitation. Here, we report experimental observations with a three-dimensional velocity-map imaging crossed-beam apparatus in the inelastic scattering process Ar++N2(v'' = 0, J'')→Ar++N2(v', J'), where all the vibrationally excited N2 products are dominated by forward scattering, contradicting the textbook model. Trajectory surface hopping calculations not only reproduced the experimental observation qualitatively, but also revealed that the vibrational excitation mainly occurs through a transient charge-transfer process. The hard collision glory mechanism, which has so far only been observed in inelastic rotational energy transfer between neutrals, is shown to play a major role for vibrational excitation in the inelastic Ar++N2 collision, via the frustrated charge transfer process.
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Affiliation(s)
- Guodong Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dandan Lu
- Department of Chemistry and Chemical Biology, Center for Computational Chemistry, University of New Mexico, Albuquerque, NM, USA
| | - Min Cheng
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, Center for Computational Chemistry, University of New Mexico, Albuquerque, NM, USA.
| | - Hong Gao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
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2
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Yang D, Guo H, Xie D. Recent advances in quantum theory on ro-vibrationally inelastic scattering. Phys Chem Chem Phys 2023; 25:3577-3594. [PMID: 36602236 DOI: 10.1039/d2cp05069b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Molecular collisions are of fundamental importance in understanding intermolecular interaction and dynamics. Its importance is accentuated in cold and ultra-cold collisions because of the dominant quantum mechanical nature of the scattering. We review recent advances in the time-independent approach to quantum mechanical characterization of non-reactive scattering in tetratomic systems, which is ideally suited for large collisional de Broglie wavelengths characteristic in cold and ultracold conditions. We discuss quantum scattering algorithms between two diatoms and between a triatom and an atom and their implementation, as well as various approximate schemes. They not only enable the characterization of collision dynamics in realistic systems but also serve as benchmarks for developing more approximate methods.
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Affiliation(s)
- Dongzheng Yang
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
| | - Daiqian Xie
- Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China. .,Hefei National Laboratory, Hefei 230088, China
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3
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Perera CA, Zuo J, Guo H, Suits AG. Differential Cross Sections for Cold, State-to-State Spin-Orbit Changing Collisions of NO( v = 10) with Neon. J Phys Chem A 2022; 126:3338-3346. [PMID: 35605132 DOI: 10.1021/acs.jpca.2c02698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Inelastic scattering processes have proven a powerful means of investigating molecular interactions, and much current effort is focused on the cold and ultracold regime where quantum phenomena are clearly manifested. Studies of collisions of the open shell nitric oxide (NO) molecule have been central in this effort since the pioneering work of Houston and co-workers in the early 1990s. State-to-state scattering of vibrationally excited molecules in the cold regime introduces challenges that test the suitability of current theoretical methods for ab initio determination of intermolecular potentials, and concomitant electronically nonadiabatic processes raise the bar further. Here we report measurements of differential cross sections for state-to-state spin-orbit changing collisions of NO (v = 10, Ω″ = 1.5, and j″ = 1.5) with neon from 2.3 to 3.5 cm-1 collision energy using our recently developed near-copropagating beam technique. The experimental results are compared with those obtained from quantum scattering calculations on a high-level set of coupled cluster potential energy surfaces and are shown to be in good agreement. The theoretical results suggest that distinct backscattering in the 2.3 cm-1 case arises from overlapping resonances.
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Affiliation(s)
- Chatura A Perera
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Junxiang Zuo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Arthur G Suits
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
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4
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Leng JG, Sharples TR, McKendrick KG, Costen ML. Stereodynamics of rotational energy transfer in NO( A2Σ +) + Kr collisions. Phys Chem Chem Phys 2022; 24:6525-6534. [PMID: 35257129 DOI: 10.1039/d1cp05960b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A crossed molecular beam, velocity-map ion imaging apparatus has been used to determine differential cross sections (DCSs) and angle-resolved rotational angular momentum alignment moments for the state-resolved rotationally inelastic scattering of NO(A2Σ+, v = 0, j = 0.5 f1) with Kr at an average collision energy of 785 cm-1. The experimental results are compared to close-coupled quantum scattering (QS) calculations performed on a literature ab initio potential energy surface (J. Kłos et al., J. Chem. Phys., 2008, 129, 244303). DCSs are very strongly forward scattered, with weaker side and backward scattered peaks becoming progressively more important at higher-N'. Good agreement is found between experimental and QS DCSs, indicating that the PES is an accurate reflection of the NO(A)-Kr interaction energies. Partial wave analysis of the QS DCSs isolates multiple scattering mechanisms contributing to the DCSs, including L-type rainbows and Fraunhofer diffraction. Measured alignment moments are not well described by a hard-shell kinematic apse scattering model, showing deviations in the forward scattering hemisphere that are in agreement with QS calculations and arise from attractive regions of the PES. These discrepancies emphasise that established scattering mechanisms for molecules such as NO with lighter noble gases cannot be extrapolated safely to heavier, more polarisable members of the series.
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Affiliation(s)
- Joseph G Leng
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK.
| | - Thomas R Sharples
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK.
| | | | - Matthew L Costen
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK.
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5
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de Jongh T, Besemer M, Shuai Q, Karman T, van der Avoird A, Groenenboom GC, van de Meerakker SYT. Imaging the onset of the resonance regime in low-energy NO-He collisions. Science 2020; 368:626-630. [DOI: 10.1126/science.aba3990] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 03/19/2020] [Indexed: 11/02/2022]
Affiliation(s)
- Tim de Jongh
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, Netherlands
| | - Matthieu Besemer
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, Netherlands
| | - Quan Shuai
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, Netherlands
| | - Tijs Karman
- Institute for Theoretical Atomic Molecular and Optical Physics, Center For Astrophysics, Harvard and Smithsonian, Cambridge, MA 02138, USA
| | - Ad van der Avoird
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, Netherlands
| | - Gerrit C. Groenenboom
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, Netherlands
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6
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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.
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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
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7
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Perreault WE, Mukherjee N, Zare RN. HD (v = 1, j = 2, m) orientation controls HD-He rotationally inelastic scattering near 1 K. J Chem Phys 2019; 150:174301. [PMID: 31067864 DOI: 10.1063/1.5096531] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
To investigate how molecular orientations affect low energy scattering, we have studied the rotational relaxation of HD (v = 1, j = 2, m) → (v' = 1, j' = 0) by collision with ground-state He, where v, j, and m designate the vibrational, rotational, and magnetic quantum numbers, respectively. We experimentally probed different collision geometries by preparing three specific m sublevels, including an m entangled sublevel, belonging to a single rovibrational (v = 1, j = 2) energy level within the ground electronic state of HD using Stark-induced adiabatic Raman passage. Low collision energies (0-5 K) were achieved by coexpanding a 1:19 HD:He mixture in a highly collimated supersonic beam, which has defined the direction of the collision velocity and restricted the incoming orbital angular momentum states, defined by the quantum number l, to l ≤ 2. Partial wave analysis of experimental data shows that a single l = 2 input orbital dominates the scattered angular distribution, implying the presence of a collisional resonance. The differential scattering angular distribution exhibits a greater than fourfold stereodynamic preference for the m = 0 input state vs m = ±2, when the quantization axis is oriented parallel to the collision velocity.
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Affiliation(s)
- William E Perreault
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Nandini Mukherjee
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Richard N Zare
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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8
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Quantum scattering theory for collisional energy transfer. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/b978-0-444-64207-3.00002-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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9
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Orr BJ. Collision-induced rovibrational energy transfer in small polyatomic molecules: the role of intramolecular perturbations. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1490463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Brian J. Orr
- Department of Physics and Astronomy, MQ Photonics Research Centre, Macquarie University, Sydney, Australia
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10
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Onvlee J, Vogels SN, van de Meerakker SYT. Unraveling Cold Molecular Collisions: Stark Decelerators in Crossed-Beam Experiments. Chemphyschem 2016; 17:3583-3595. [PMID: 27471830 DOI: 10.1002/cphc.201600604] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Indexed: 11/11/2022]
Abstract
In the last two decades, enormous progress has been made in the manipulation of molecular beams. In particular, molecular decelerators have been developed with which advanced control over neutral molecules in a beam can be achieved. By using arrays of inhomogeneous and time-varying electric (or magnetic) fields, bunches of molecules can be produced with a tunable velocity, narrow velocity spreads, and almost perfect quantum-state purity. These monochromatic or "tamed" molecular beams are ideally suited to be used in crossed-molecular-beam scattering experiments. Here, we review the first generation of these "cold and controlled" scattering experiments that have been conducted in the last decade and discuss the prospects for this emerging field of research in the years to come.
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Affiliation(s)
- Jolijn Onvlee
- Radboud University, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
| | - Sjoerd N Vogels
- Radboud University, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
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11
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Luxford TFM, Sharples TR, McKendrick KG, Costen ML. Experimental testing of ab initio potential energy surfaces: Stereodynamics of NO(A 2Σ +) + Ne inelastic scattering at multiple collision energies. J Chem Phys 2016; 145:174304. [PMID: 27825214 DOI: 10.1063/1.4966688] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a crossed molecular beam velocity-map ion imaging study of state-to-state rotational energy transfer of NO(A2Σ+, v = 0, N = 0, j = 0.5) in collisions with Ne atoms. From these measurements, we report differential cross sections and angle-resolved rotational angular momentum alignment moments for product states N' = 3 and 5-10 for collisions at an average energy of 523 cm-1, and N' = 3 and 5-14 for collisions at an average energy of 1309 cm-1, respectively. The experimental results are compared to the results of close-coupled quantum scattering calculations on two literature ab initio potential energy surfaces (PESs) [Pajón-Suárez et al., Chem. Phys. Lett. 429, 389 (2006) and Cybulski and Fernández, J. Phys. Chem. A 116, 7319 (2012)]. The differential cross sections from both experiment and theory show clear rotational rainbow structures at both collision energies, and comparison of the angles observed for the rainbow peaks leads to the conclusion that Cybulski and Fernández PES better represents the NO(A2Σ+)-Ne interaction at the collision energies used here. Sharp, forward scattered (<10°), peaks are observed in the experimental differential cross sections for a wide range of N' at both collision energies, which are not reproduced by theory on either PES. We identify these as L-type rainbows, characteristic of attractive interactions, and consistent with a shallow well in the collinear Ne-N-O geometry, similar to that calculated for the NO(A2Σ+)-Ar surface [Kłos et al., J. Chem. Phys. 129, 244303 (2008)], but absent from both of the NO(A2Σ+)-Ne surfaces tested here. The angle-resolved alignment moments calculated by quantum scattering theory are generally in good agreement with the experimental results, but both experiment and quantum scattering theories are dramatically different to the predictions of a classical rigid-shell, kinematic-apse conservation model. Strong oscillations are resolved in the experimental alignment moments as a function of scattering angle, confirming and extending the preliminary report of this behavior [Steill et al., J. Phys. Chem. A 117, 8163 (2013)]. These oscillations are correlated with structure in the differential cross section, suggesting an interference effect is responsible for their appearance.
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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
| | - 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
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12
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Imaging quantum stereodynamics through Fraunhofer scattering of NO radicals with rare-gas atoms. Nat Chem 2016; 9:226-233. [DOI: 10.1038/nchem.2640] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 09/08/2016] [Indexed: 11/08/2022]
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13
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Murray MJ, Ogden HM, Toro C, Liu Q, Mullin AS. Impulsive Collision Dynamics of CO Super Rotors from an Optical Centrifuge. Chemphyschem 2016; 17:3692-3700. [DOI: 10.1002/cphc.201600871] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 09/28/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Matthew J. Murray
- Department of Chemistry and Biochemistry University of Maryland College Park MD USA
| | - Hannah M. Ogden
- Department of Chemistry and Biochemistry University of Maryland College Park MD USA
| | - Carlos Toro
- Department of Chemistry and Biochemistry University of Maryland College Park MD USA
| | - Qingnan Liu
- National Institute of Standards and Technology 100 Bureau Drive, Stop 8320 Gaithersburg MD 20899 USA
| | - Amy S. Mullin
- Department of Chemistry and Biochemistry University of Maryland College Park MD USA
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14
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Beutner V, Zhang SG, Meyer H, Kłos J. The near-IR spectrum of NO(X̃ 2Π)-He detected through excitation into the Ã-state continuum: A joint experimental and theoretical study. J Chem Phys 2016; 145:124318. [PMID: 27782644 DOI: 10.1063/1.4963228] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present the first measurement of a bound-state spectrum of the NO-He complex. The recorded spectrum is associated with the first overtone transition of the NO moiety. The IR absorption is detected by exciting the vibrationally excited complex to the Ã-state dissociation continuum. The resulting NO(A) fragment is subsequently ionized in the same laser pulse. We recorded two bands centered around the NO monomer rotational lines, Q11(0.5) and R11(0.5), consistent with an almost free rotation of the NO fragment within the complex. The origin of the spectrum is found at 3724.06 cm-1 blue shifted by 0.21 cm-1 from the corresponding NO monomer origin. The rotational structures of the spectrum are found to be in very good agreement with calculated spectra based on bound states derived from a set of high level ab initio potential energy surfaces [Kłos et al. J. Chem. Phys. 112, 2195 (2000)].
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Affiliation(s)
- V Beutner
- Department of Physics and Astronomy, The University of Georgia, Athens, Georgia 30602-2451, USA
| | - S G Zhang
- Department of Physics and Astronomy, The University of Georgia, Athens, Georgia 30602-2451, USA
| | - H Meyer
- Department of Physics and Astronomy, The University of Georgia, Athens, Georgia 30602-2451, USA
| | - J Kłos
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742-2021, USA
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15
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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.
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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
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16
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Murray MJ, Ogden HM, Toro C, Liu Q, Burns DA, Alexander MH, Mullin AS. State-Specific Collision Dynamics of Molecular Super Rotors with Oriented Angular Momentum. J Phys Chem A 2015; 119:12471-9. [DOI: 10.1021/acs.jpca.5b07941] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew J. Murray
- Department
of Chemistry and
Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Hannah M. Ogden
- Department
of Chemistry and
Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Carlos Toro
- Department
of Chemistry and
Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Qingnan Liu
- Department
of Chemistry and
Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - David A. Burns
- Department
of Chemistry and
Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Millard H. Alexander
- Department
of Chemistry and
Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Amy S. Mullin
- Department
of Chemistry and
Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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17
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Steill JD, Jasper AW, Chandler DW. Determination of the collisional energy transfer distribution responsible for the collision-induced dissociation of NO2 with Ar. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.06.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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18
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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
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19
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McGurk SJ, Halpern JB, McKendrick KG, Costen ML. Parity-dependent rotational energy transfer in CN(A(2)Π, ν = 4, j F(1)ε) + N2, O2, and CO2 collisions. J Phys Chem A 2014; 118:2007-17. [PMID: 24552624 PMCID: PMC4004332 DOI: 10.1021/jp4123503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report state-resolved total removal cross sections and state-to-state rotational energy transfer (RET) cross sections for collisions of CN(A(2)Π, ν = 4, j F1ε) with N2, O2, and CO2. CN(X(2)Σ(+)) was produced by 266 nm photolysis of ICN in a thermal bath (296 K) of the collider gas. A circularly polarized pulse from a dye laser prepared CN(A(2)Π, ν = 4) in a range of F1e rotational states, j = 2.5, 3.5, 6.5, 11.5, 13.5, and 18.5. These prepared states were monitored using the circularly polarized output of an external cavity diode laser by frequency-modulated (FM) spectroscopy on the CN(A-X)(4,2) band. The FM Doppler profiles were analyzed as a function of pump-probe delay to determine the time dependence of the population of the initially prepared states. Kinetic analysis of the resulting time dependences was used to determine total removal cross sections from the initially prepared levels. In addition, a range of j' F1e and j' F2f product states resulting from rotational energy transfer out of the j = 6.5 F1e initial state were probed, from which state-to-state RET cross sections were measured. The total removal cross sections lie in the order CO2 > N2 > O2, with evidence for substantial cross sections for electronic and/or reactive quenching of CN(A, ν = 4) to unobserved products with CO2 and O2. This is supported by the magnitude of the state-to-state RET cross sections, where a deficit of transferred population is apparent for CO2 and O2. A strong propensity for conservation of rotational parity in RET is observed for all three colliders. Spin-orbit-changing cross sections are approximately half of those of the respective conserving cross sections. These results are in marked disagreement with previous experimental observations with N2 as a collider but are in good agreement with quantum scattering calculations from the same study ( Khachatrian et al. J. Phys. Chem. A 2009 , 113 , 3922 ). Our results with CO2 as a collider are similarly in strong disagreement with a related experimental study ( Khachatrian et al. J. Phys. Chem. A 2009 , 113 , 13390 ). We therefore propose that the previous experiments substantially underestimated the spin-orbit-changing cross sections for collisions with both N2 and CO2, suggesting that even approximate quantum scattering calculations may be more successful for such molecule-molecule systems than was previously concluded.
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Affiliation(s)
- Stephen J McGurk
- Institute of Chemical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
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Roueff E, Lique F. Molecular Excitation in the Interstellar Medium: Recent Advances in Collisional, Radiative, and Chemical Processes. Chem Rev 2013; 113:8906-38. [DOI: 10.1021/cr400145a] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Evelyne Roueff
- Laboratoire
Univers et Théories, Observatoire de Paris, 92190 Meudon, France
| | - François Lique
- LOMC - UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 540, 76058 Le Havre, France
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21
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McGurk SJ, McKendrick KG, Costen ML, Alexander MH, Dagdigian PJ. Parity-dependent oscillations in collisional polarization transfer: CN(A²Π, v = 4) + Ar. J Chem Phys 2013; 139:124304. [PMID: 24089764 DOI: 10.1063/1.4821602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report the first systematic experimental and theoretical study of the state-to-state transfer of rotational angular momentum orientation in a (2)Π-rare gas system. CN(X(2)Σ(+)) was produced by pulsed 266 nm photolysis of ICN in a thermal bath (296 K) of Ar collider gas. A pulsed circularly polarized tunable dye laser prepared CN(A(2)Π, v = 4) in two fully state-selected initial levels, j = 6.5 F1e and j = 10.5 F2f, with a known laboratory-frame orientation. Both the prepared levels and a range of product levels, j' F1e and j' F2f, were monitored using the circular polarized output of a tunable diode laser via cw frequency-modulated (FM) spectroscopy in stimulated emission on the CN(A-X) (4,2) band. The FM Doppler lineshapes for co-rotating and counter-rotating pump-and-probe geometries reveal the time-dependence of the populations and orientations. Kinetic fitting was used to extract the state-to-state population transfer rate constants and orientation multipole transfer efficiencies (MTEs), which quantify the degree of conservation of initially prepared orientation in the product level. Complementary full quantum scattering (QS) calculations were carried out on recently computed ab initio potential energy surfaces. Collision-energy-dependent tensor cross sections for ranks K = 0 and 1 were computed for transitions from both initial levels to all final levels. These quantities were integrated over the thermal collision energy distribution to yield predictions of the experimentally observed state-to-state population transfer rate constants and MTEs. Excellent agreement between experiment and theory is observed for both measured quantities. Dramatic oscillations in the MTEs are observed, up to and including changes in the sign of the orientation, as a function of even/odd Δj within a particular spin-orbit and e/f manifold. These oscillations, along with those also observed in the state-to-state rate constants, reflect the rotational parity of the final level. In general, parity-conserving collisions conserve rotational orientation, while parity-changing collisions result in large changes in the orientation. The QS calculations show that the dynamics of the collisions leading to these different outcomes are fundamentally different. We propose that the origin of this behavior lies in interferences between collisions that sample the even and odd-λ terms in the angular expansions of the PESs.
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Affiliation(s)
- S J McGurk
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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22
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Kirste M, Haak H, Meijer G, van de Meerakker SYT. A compact hexapole state-selector for NO radicals. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:073113. [PMID: 23902050 DOI: 10.1063/1.4812267] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Focusing of molecular beams using an electrostatic hexapole is a mature technique to produce samples of state-selected molecules. The ability to efficiently focus molecules depends on the properties of the molecular species of interest, the length of the hexapole state selector, as well as on the maximum electric field strength that can be achieved in these devices. In particular for species with a small effective dipole moment such as nitric oxide (NO), hexapole state selectors of several meters in length are required to focus the beam. We report on a novel design for an electrostatic hexapole state-selector that allows for a maximum electric field strength of 260 kV/cm, reducing significantly the length of the hexapole that is required to focus the beam. We demonstrate the focusing of a molecular beam of NO radicals (X (2)Π1∕2, v = 0, J = 1∕2, f) using a hexapole of only 30 cm length. A beamstop is integrated inside the hexapole at the geometric center of the device where the molecular trajectories have the largest deviation from the beam axis, effectively blocking the carrier gas of the molecular beam at minimum loss of NO density. The performance of the hexapole state-selector is investigated by state-selective laser induced fluorescence detection, as well as by two-dimensional imaging of the focused packet of NO radicals. The resulting packet of NO radicals has a density of 9 ± 3 × 10(10) cm(-3) and a state purity of 99%.
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Affiliation(s)
- Moritz Kirste
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
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23
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Dagdigian PJ. Theoretical investigation of collisional energy transfer in polyatomic intermediates. INT REV PHYS CHEM 2013. [DOI: 10.1080/0144235x.2012.758543] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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24
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Dagdigian PJ, Alexander MH. Exact quantum scattering calculations of transport properties: CH2(X̃3B1, ã1A1)–helium. J Chem Phys 2013; 138:164305. [DOI: 10.1063/1.4801789] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Tkáč O, Sage AG, Greaves SJ, Orr-Ewing AJ, Dagdigian PJ, Ma Q, Alexander MH. Rotationally inelastic scattering of CD3 and CH3 with He: comparison of velocity map-imaging data with quantum scattering calculations. Chem Sci 2013. [DOI: 10.1039/c3sc52002a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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26
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Ajili Y, Hammami K, Jaidane NE, Lanza M, Kalugina YN, Lique F, Hochlaf M. On the accuracy of explicitly correlated methods to generate potential energy surfaces for scattering calculations and clustering: application to the HCl–He complex. Phys Chem Chem Phys 2013; 15:10062-70. [DOI: 10.1039/c3cp44708a] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Kirste M, Wang X, Schewe HC, Meijer G, Liu K, van der Avoird A, Janssen LMC, Gubbels KB, Groenenboom GC, van de Meerakker SYT. Quantum-State Resolved Bimolecular Collisions of Velocity-Controlled OH with NO Radicals. Science 2012. [DOI: 10.1126/science.1229549] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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28
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Dagdigian PJ, Alexander MH. Exact quantum scattering calculation of transport properties for free radicals: OH(X2Π)–helium. J Chem Phys 2012; 137:094306. [DOI: 10.1063/1.4748141] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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29
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Kay JJ, Steill JD, Kłos J, Paterson G, Costen ML, Strecker KE, McKendrick KG, Alexander MH, Chandler DW. Collisions of electronically excited molecules: differential cross-sections for rotationally inelastic scattering of NO(A2Σ+) with Ar and He. Mol Phys 2012. [DOI: 10.1080/00268976.2012.670283] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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30
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McGurk SJ, McKendrick KG, Costen ML, Bennett DIG, Kłos J, Alexander MH, Dagdigian PJ. Depolarization of rotational angular momentum in CN(A2Π, v = 4) + Ar collisions. J Chem Phys 2012; 136:164306. [PMID: 22559481 DOI: 10.1063/1.4705118] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Angular momentum depolarization and population transfer in CN(A(2)Π, v = 4, j, F(1)e) + Ar collisions have been investigated both experimentally and theoretically. Ground-state CN(X(2)Σ(+)) molecules were generated by pulsed 266-nm laser photolysis of ICN in a thermal (nominally 298 K) bath of the Ar collision partner at a range of pressures. The translationally thermalized CN(X) radicals were optically pumped to selected unique CN(A(2)Π, v = 4, j = 2.5, 3.5, 6.5, 11.5, 13.5, and 18.5, F(1)e) levels on the A-X (4,0) band by a pulsed tunable dye laser. The prepared level was monitored in a collinear geometry by cw frequency-modulated (FM) spectroscopy in stimulated emission on the CN(A-X) (4,2) band. The FM lineshapes for co- and counter-rotating circular pump and probe polarizations were analyzed to extract the time dependence of the population and (to a good approximation) orientation (tensor rank K = 1 polarization). The corresponding parallel and perpendicular linear polarizations yielded population and alignment (K = 2). The combined population and polarization measurements at each Ar pressure were fitted to a 3-level kinetic model, the minimum complexity necessary to reproduce the qualitative features of the data. Rate constants were extracted for the total loss of population and of elastic depolarization of ranks K = 1 and 2. Elastic depolarization is concluded to be a relatively minor process in this system. Complementary full quantum scattering (QS) calculations were carried out on the best previous and a new set of ab initio potential energy surfaces for CN(A)-Ar. Collision-energy-dependent elastic tensor and depolarization cross sections for ranks K = 1 and 2 were computed for CN(A(2)Π, v = 4, j = 1.5-10.5, F(1)e) rotational/fine-structure levels. In addition, integral cross sections for rotationally inelastic transitions out of these levels were computed and summed to yield total population transfer cross sections. These quantities were integrated over a thermal collision-energy distribution to yield the corresponding rate constants. A complete master-equation simulation using the QS results for the selected initial level j = 6.5 gave close, but not perfect, agreement with the near-exponential experimental population decays, and successfully reproduced the observed multimodal character of the polarization decays. On average, the QS population removal rate constants were consistently 10%-15% higher than those derived from the 3-level fit to the experimental data. The QS and experimental depolarization rate constants agree within the experimental uncertainties at low j, but the QS predictions decline more rapidly with j than the observations. In addition to providing a sensitive test of the achievable level of agreement between state-of-the art experiment and theory, these results highlight the importance of multiple collisions in contributing to phenomenological depolarization using any method sensitive to both polarized and unpolarized molecules in the observed level.
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Affiliation(s)
- S J McGurk
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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31
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Paterson G, Costen ML, McKendrick KG. Collisional depolarisation of rotational angular momentum: influence of the potential energy surface on the collision dynamics? INT REV PHYS CHEM 2012. [DOI: 10.1080/0144235x.2012.659046] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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32
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Paterson G, Relf A, Costen ML, McKendrick KG, Alexander MH, Dagdigian PJ. Rotationally elastic and inelastic dynamics of NO(X2Π, v = 0) in collisions with Ar. J Chem Phys 2011; 135:234304. [PMID: 22191872 DOI: 10.1063/1.3665135] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A combined theoretical and experimental study of the depolarization of selected NO(X(2)Π, v = 0, j, F, ɛ) levels in collisions with a thermal bath of Ar has been carried out. Rate constants for elastic depolarization of rank K = 1 (orientation) and K = 2 (alignment) were extracted from collision-energy-dependent quantum scattering calculations, along with those for inelastic population transfer to discrete product levels. The rate constants for total loss of polarization of selected initial levels, which are the sum of elastic depolarization and population transfer contributions, were measured using a two-color polarization spectroscopy technique. Theory and experiment agree qualitatively that the rate constants for total loss of polarization decline modestly with j, but the absolute values differ by significantly more than the statistical uncertainties in the measurements. The reasons for this discrepancy are as yet unclear. The lack of a significant K dependence in the experimental data is, however, consistent with the theoretical prediction that elastic depolarization makes only a modest contribution to the total loss of polarization. This supports a previous conclusion that elastic depolarization for NO(X(2)Π) + Ar is significantly less efficient than for the electronically closely related system OH(X(2)Π) + Ar [P. J. Dagdigian and M. H. Alexander, J. Chem. Phys. 130, 204304 (2009)].
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Affiliation(s)
- G Paterson
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, United Kingdom
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33
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Paterson G, Costen ML, McKendrick KG. Collisional depolarization of rotational angular momentum: what are the observables and how can they be measured? Mol Phys 2011. [DOI: 10.1080/00268976.2011.621901] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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34
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Dagdigian PJ, Alexander MH. Theoretical investigation of rotationally inelastic collisions of the methyl radical with helium. J Chem Phys 2011; 135:064306. [DOI: 10.1063/1.3624525] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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35
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Ma L, Alexander MH, Dagdigian PJ. Theoretical investigation of rotationally inelastic collisions of CH2(ã) with helium. J Chem Phys 2011; 134:154307. [DOI: 10.1063/1.3575200] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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36
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Kay JJ, Paterson G, Costen ML, Strecker KE, McKendrick KG, Chandler DW. Communication: direct angle-resolved measurements of collision dynamics with electronically excited molecules: NO(A2Σ+) + Ar. J Chem Phys 2011; 134:091101. [PMID: 21384942 DOI: 10.1063/1.3563016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We report direct doubly differential (quantum state and angle-resolved) scattering measurements involving short-lived electronically excited molecules using crossed molecular beams. In our experiment, supersonic beams of nitric oxide and argon atoms collide at 90°. In the crossing region, NO molecules are excited to the A(2)Σ(+)state by a pulsed nanosecond laser, undergo rotationally inelastic collisions with Ar atoms, and are then detected 400 ns later (approximately twice the radiative lifetime of the A(2)Σ(+)state) by 1 + 1(') multiphoton ionization via the E(2)Σ(+) state. The velocity distributions of the scattered molecules are recorded using velocity-mapped ion imaging. The resulting images provide a direct measurement of the state-to-state differential scattering cross sections. These results demonstrate that sufficient scattering events occur during the short lifetimes typical of molecular excited states (∼200 ns, in this case) to allow spectroscopically detected quantum-state-resolved measurements of products of excited-state collisions.
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Affiliation(s)
- Jeffrey J Kay
- Sandia National Laboratories, Livermore, California 94550, USA
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37
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Doménech JL, Martínez RZ, Ramos A, Bermejo D. Direct determination of state-to-state rotational energy transfer rate constants via a Raman-Raman double resonance technique: ortho-acetylene in v(2)=1 at 155 K. J Chem Phys 2010; 132:154303. [PMID: 20423177 DOI: 10.1063/1.3374031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A new technique for the direct determination of state-to-state rotational energy transfer rate constants in the gas phase is presented. It is based on two sequential stimulated Raman processes: the first one prepares the sample in a single rotational state of an excited vibrational level, and the second one, using the high resolution quasi-continuous stimulated Raman-loss technique, monitors the transfer of population to other rotational states of the same vibrational level as a function of the delay between the pump and the probe stages. The technique is applied to the odd-J rotational states of v(2)=1 acetylene at 155 K. The experimental layout, data acquisition, retrieval procedures, and numerical treatment are described. The quantity and quality of the data are high enough to allow a direct determination of the state-to-state rate constant matrix from a fit of the experimental data, with the only conditions of detailed balance and of a closed number of states. The matrix obtained from this direct fit is also compared with those obtained using some common fitting and scaling laws.
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Affiliation(s)
- José L Doménech
- Instituto de Estructura de la Materia (CSIC), Serrano 123, E-28006 Madrid, Spain.
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38
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Ballingall I, Rutherford MF, McKendrick KG, Costen ML. Elastic depolarization and polarization transfer in CN(A2Π,v= 4)+Ar collisions. Mol Phys 2010. [DOI: 10.1080/00268970903476670] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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39
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40
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Lemeshko M, Friedrich B. Model Analysis of Rotationally Inelastic Ar + H2O Scattering in an Electric Field. J Phys Chem A 2009; 113:15055-63. [DOI: 10.1021/jp9051598] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mikhail Lemeshko
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Bretislav Friedrich
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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41
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Dagdigian PJ, Alexander MH. Tensor cross sections and collisional depolarization of OH(X 2Π) in collisions with helium. J Chem Phys 2009; 130:164315. [DOI: 10.1063/1.3119978] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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42
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Dagdigian PJ, Alexander MH. Tensor cross sections and the collisional evolution of state multipoles: OH(XΠ2)–Ar. J Chem Phys 2009; 130:094303. [DOI: 10.1063/1.3078386] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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43
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Paterson G, Marinakis S, Kłos J, Costen ML, McKendrick KG. Depolarisation of rotational orientation and alignment in OH (X2Π) + Xe collisions. Phys Chem Chem Phys 2009; 11:8804-12. [DOI: 10.1039/b909050a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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44
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Paterson G, Marinakis S, Costen ML, McKendrick KG. Depolarisation of rotational orientation and alignment of OH (X2Π) in collisions with molecular partners: N2 and O2. Phys Chem Chem Phys 2009; 11:8813-20. [DOI: 10.1039/b909051g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Paterson G, Marinakis S, Costen ML, McKendrick KG, Kłos J, Toboła R. Orientation and alignment depolarization in OH(X Π2)+Ar/He collisions. J Chem Phys 2008; 129:074304. [DOI: 10.1063/1.2967861] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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46
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Costen ML, Marinakis S, McKendrick KG. Do vectors point the way to understanding energy transfer in molecular collisions? Chem Soc Rev 2008; 37:732-43. [DOI: 10.1039/b618070c] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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47
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Alagappan A, Ballingall I, Costen ML, McKendrick KG. Differential scattering cross-sections for CNA2Π+Ar. J Chem Phys 2007; 126:041103. [PMID: 17286454 DOI: 10.1063/1.2437164] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present the first results from a novel experimental approach to the measurement of state-to-state differential scattering cross-sections for inelastic scattering of electronically excited CN A(2)Pi with Ar. Photodissociation of ICN with linearly polarized 266 nm radiation generates CN X(2)Sigma(+) (upsilon(")=0,J(")) with a near mono-energetic speed distribution and large anisotropy. Saturated optical pumping of the nascent CN X(2)Sigma(+) transfers this speed distribution without distortion to selected rotational quantum states of the A(2)Pi (upsilon(')=4) level. The products of rotational energy transfer within the A(2)Pi (upsilon(')=4) level into the J(')=0.5, F(2), f, state are probed using frequency modulated stimulated emission spectroscopy on the A-X (4,2) band with a single frequency external cavity tunable diode laser. Doppler profiles of transitions from individual rotational, spin-orbit and lambda doublet specific levels are acquired for different geometrical arrangements of photolysis polarization and probe propagation directions. The resulting Doppler profiles, which for this J(')=0.5 state cannot display a rotational angular momentum alignment, are combined to yield composite Doppler profiles depending on speed and translational anisotropy, which are analyzed to determine fully state-to-state resolved differential scattering cross-sections.
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Affiliation(s)
- Azhagammai Alagappan
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
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48
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Marinakis S, Paterson G, Kłos J, Costen ML, McKendrick KG. Inelastic scattering of OH(X 2Π) with Ar and He: a combined polarization spectroscopy and quantum scattering study. Phys Chem Chem Phys 2007; 9:4414-26. [PMID: 17687488 DOI: 10.1039/b703909c] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
One-colour polarization spectroscopy (PS) on the OH A (2)Sigma(+)- X (2)Pi(0,0) band has been used to measure the removal of bulk rotational angular momentum alignment of ground-state OH(X (2)Pi) in collisions with He and Ar. Pseudo-first-order PS signal decays at different collider partial pressures were used to determine second-order decay rate constants for the X (2)Pi(3/2), J = 1.5-6.5, e states. The PS signal decay rate constant, k(PS), is sensitive to all processes that remove population and destroy polarization. The contribution to k(PS) from pure (elastic) alignment depolarization within the initial level, k(DEP), can be extracted by subtracting the independently measured or predicted sum of the rate constants for total rotational energy transfer (RET), k(RET), and for Lambda-doublet changing, k(Lambda), collisions from k(PS). Literature values of k(RET) and k(Lambda) are available from experiments with He and Ar, and from quantum scattering calculations for Ar only. We therefore also present the results of new, exact, fully quantum mechanical calculations of k(RET) and k(Lambda) on the most recent ab initio OH(X)-He potential energy surface of Lee et al. [J. Chem. Phys. 2000, 113, 5736]. The results for k(DEP) from this subtraction for He are found to be modest, around 0.4 x 10(-10) cm(3) s(-1), whereas for Ar k(DEP) is found to range between 0.6 +/- 0.2 x 10(-10) cm(3) s(-1) and 1.7 +/- 0.3 x 10(-10) cm(3) s(-1), comparable to total population removal rate constants. The differences between k(DEP) for the two colliders are most likely explained by the presence of a substantially deeper attractive well for Ar than for He. The measurement of k(DEP) may provide a useful new tool that is more sensitive to the form of the long-range part of the intermolecular potential than rotational state-changing collisions.
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Affiliation(s)
- Sarantos Marinakis
- School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, UK
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Alagappan A, Ballingall I, Costen ML, McKendrick KG, Paterson G. Efficiencies of state and velocity-changing collisions of superthermal CN A2Π with He, Ar, N2and O2. Phys Chem Chem Phys 2007; 9:747-54. [PMID: 17268687 DOI: 10.1039/b614965k] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Polarized laser photolysis of ICN is combined with saturated optical pumping to prepare state-selected CN Alpha(2)Pi (nu' = 4, J = 0.5, F(2), f) with a well-defined anisotropic superthermal speed distribution. The collisional evolution of the prepared state is observed by Doppler-resolved Frequency Modulated (FM) spectroscopy via stimulated emission on the CN Alpha(2)Pi-Chi(2)Sigma(+) (4,2) band. The phenomenological rate constants for removal of the prepared state in collisions with He, Ar, N(2) and O(2) are reported. The observed collision cross-sections are consistent with attractive forces contributing significantly for all the colliders with the exception of He. The collisional evolution of the prepared velocity distribution demonstrates that no significant back-transfer into the prepared level occurs, and that any elastic scattering is strongly in the forward hemisphere.
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Affiliation(s)
- Azhagammai Alagappan
- School of Engineering and Physical Sciences, William H Perkin Building, Heriot-Watt University, Edinburgh, UK
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Clegg SM, Parmenter CS. Inelastic scattering from glyoxal: collision kinematics rather than the interaction potential dominates rotational channel selection. J Chem Phys 2006; 125:133110. [PMID: 17029436 DOI: 10.1063/1.2336222] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Relative cross sections have been obtained for the rotationally and rovibrationally inelastic scattering of S1 trans-glyoxal (CHO-CHO) in its zero point level with K' = 0 from the target gases H2, D2, and He. Emphasis is placed on using crossed molecular beam conditions that provide several choices of collision kinematics (center-of-mass collision energy, relative velocity, center-of-mass collision momentum) for each collision pair. The cross sections define the state-to-state competition among numerous rotational channels involving destination states with DeltaK' ranging from 1 to >15 for collisions with each target gas and under every kinematic condition. They also resolve a similar rotational competition among rovibrational channels where the torsion nu7' is collisionally excited. The cross section sets also allow the relative overall magnitudes of the two types of scattering to be compared. The primary motivation of these experiments concerns the rotationally inelastic scattering. Earlier studies with rare gases and fixed kinematics demonstrated that the distribution of rotational cross sections is remarkably similar from one collision pair to another. The new data show that the competition among rotational channels actually has a small but distinct dependence on kinematic conditions. Data analysis shows that the dependence is a systematic function of the available collision momentum and entirely unrelated to the identity of the target gases, including the heavier rare gases used in earlier studies. The competition among the rotational energy transfer channels and its kinematic heritage is discussed in the context of a classical hard ellipse model of linear momentum to angular momentum conversion much used with room temperature systems. When adapted to our beam conditions, the resulting account of the rotational scattering is accurate and provides insight into the collisional details.
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Affiliation(s)
- Samuel M Clegg
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
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