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Beek, M. C. van; Berden, Giel; Bethlem, Hendrick L.; Meulen, J. J. ter

doi:10.1103/physrevlett.86.4001

Cited by 36 publications

(28 citation statements)

References 17 publications

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“…They found an intriguing angular, oscillating dependence of the orientation as a function of scattering angle. Van Beck et al 9 observed orientational effects in OH͑X 2 ⌸͒ -Ar rotationally inelastic collisions in a crossed beam experiment, and differential and integral cross sections for reorientation of the molecular axis were determined as a function of the initial orientation. Stolte and co-workers 10,11 investigated the steric asymmetry in rotationally inelastic collisions of NO͑X 2 ⌸͒ with several collision partners.…”

Section: Introductionmentioning

confidence: 99%

Tensor cross sections and the collisional evolution of state multipoles: OH(XΠ2)–Ar

Dagdigian

Alexander

2009

The Journal of Chemical Physics

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By means of a kinetic analysis, we show that the overall rate constant for the collisional loss of orientation or alignment of a rotational level is the sum of the rate constant for elastic depolarization and the sum of the rate constants for all rotationally inelastic transitions out of the level under consideration. An expression for the depolarization cross section is derived in terms of tensor cross sections, and the relationship of depolarization to m-resolved transitions is discussed. We use this formalism in simulations, based on high-quality ab initio potential energy surfaces, of the depolarization of the open-shell molecule OH(X (2)Pi) through collisions with Ar. Good agreement is seen with the results of the two-color polarization spectroscopy experiments of Paterson et al. [J. Chem. Phys. 129, 074304 (2008)]. In addition, we show that the major contribution to elastic collisional depolarization occurs not from weak, glancing collisions but from encounters which probe the inner wall of the potential energy surface.

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Section: Introductionmentioning

confidence: 99%

Tensor cross sections and the collisional evolution of state multipoles: OH(XΠ2)–Ar

Dagdigian

Alexander

2009

The Journal of Chemical Physics

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“…31 The collision induced reorientation of the OH radicals was measured by probing the Stark-split states of the products corresponding to different orientations. 32 Under thermal bulk conditions, the evolution of oriented or aligned OH (X 2 P) radicals was studied in collisions with argon by polarization spectroscopy. 33,34 Detailed information on the OH(X 2 P)-Ar PES has also been obtained from spectroscopic study of the bound states of the OH-Ar van der Waals complex.…”

Section: Introductionmentioning

confidence: 99%

State-to-state inelastic scattering of Stark-decelerated OH radicals with Ar atoms

Scharfenberg

Kłos

Dagdigian

et al. 2010

Phys. Chem. Chem. Phys.

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The Stark deceleration method exploits the concepts of charged particle accelerator physics to produce molecular beams with a tunable velocity. These tamed molecular beams offer interesting perspectives for precise crossed beam scattering studies as a function of the collision energy. The method has advanced sufficiently to compete with state-of-the-art beam methods that are used for scattering studies throughout. This is demonstrated here for the scattering of OH radicals (X 2 P 3/2 , J = 3/2, f) with Ar atoms, a benchmark system for the scattering of open-shell molecules with atoms. Parity-resolved integral state-to-state inelastic scattering cross sections are measured at collision energies between 80 and 800 cm À1 . The threshold behavior and collision energy dependence of 13 inelastic scattering channels is accurately determined. Excellent agreement is obtained with the cross sections predicted by close-coupling scattering calculations based on the most accurate ab initio OH + Ar potential energy surfaces to date.

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“…Further state selection can be achieved by optical preparation of a single quantum state or by purification of the beam with the use of electrostatic or magnetic multipole fields (2,3 ). These methods allow the orientation of the molecules to be controlled before the collision (8,9 ) and the orientation of the scattered products can be measured (10 ).…”

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confidence: 99%

Near-Threshold Inelastic Collisions Using Molecular Beams with a Tunable Velocity

Gilijamse

Hoekstra

Meerakker

et al. 2006

Science

230

268

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Molecular scattering behavior has generally proven difficult to study at low collision energies. We formed a molecular beam of OH radicals with a narrow velocity distribution and a tunable absolute velocity by passing the beam through a Stark decelerator. The transition probabilities for inelastic scattering of the OH radicals with Xe atoms were measured as a function of the collision energy in range of 50 to 400 wavenumber, with an overall energy resolution of about 13 wavenumbers. The behavior of the cross sections for inelastic scattering near the energetic thresholds was accurately measured, and excellent agreement was obtained with cross-sections derived from coupled-channel calculations on ab initio computed potential energy surfaces.The study of collisions between gas-phase atoms and molecules is a well-established method of gathering detailed information about their individual structures and mutual interaction (1 ). The level of detail obtained by these studies depends on the quality of preparation of the collision partners before the collision (2-4 ) and on how accurately the products are analyzed afterward (5-7 ). In recent years, it has become increasingly possible to control the internal and external degrees of freedom of the scattering partners, allowing the potential energy surfaces that govern the molecular collisions to be probed in ever greater detail. The most detailed information is obtained when crossed molecular beams are used to produce intense jets of molecules with a well-defined velocity, confined to only a few internal quantum states. Further state selection can be achieved by optical preparation of a single quantum state or by purification of the beam with the use of electrostatic or magnetic multipole fields (2, 3 ). These methods allow the orientation of the molecules to be controlled before the collision (8, 9 ) and the orientation of the scattered products can be measured (10 ).One of the most important parameters describing a scattering event is the collision energy of the scatterers. However, control over the collision energy has been a difficult experimental task. Since the 1980's, ingenious crossed beam machines have been engineered to vary the crossing angle of the intersecting beams, allowing variation of the collision energy while maintaining particle densities high enough for scattering (11 ). It was thereby possible to measure threshold behavior of rotational energy transfer (12, 13 ), or to tune the collision energy over the reaction barrier for reactive scattering (14, 15 ). These methods led to considerable improvement in the control over collision energy at high energiesfor example to probe short-range interactions. However, a similar level of control over collisions at low energies, which are sensitive probes for long-range interactions, is generally lacking. The angle of the 1

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Molecular Reorientation in Collisions ofOH+Ar

Cited by 36 publications

References 17 publications

Tensor cross sections and the collisional evolution of state multipoles: OH(XΠ2)–Ar

Tensor cross sections and the collisional evolution of state multipoles: OH(XΠ2)–Ar

State-to-state inelastic scattering of Stark-decelerated OH radicals with Ar atoms

Near-Threshold Inelastic Collisions Using Molecular Beams with a Tunable Velocity

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