Rotationally inelastic collisions of OH(X 2Π)+Ar. I. State-to-state cross sections

Beek, M. C. van; Meulen, J. J. ter; Alexander, M. H.

doi:10.1063/1.481839

Cited by 52 publications

(38 citation statements)

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“…Collisions populating the F 1 (3/2e) level were most likely. Within the F 1 (5/2) level, collisions populating the lower Λ-doublet component of e parity were favored, consistent with findings of other 2 Π-rare gas systems (28,29 ). For the F 1 (3/2e) and the F 1 (5/2e/f ) levels, the transition probabilities were almost constant at higher collision energies.…”

supporting

confidence: 73%

“…In a crossed beam set-up, rotationally inelastic scattering between state-selected OH radicals (X 2 Π 3/2 , v = 0, J = 3/2, f (27 ), referred to hereafter as F 1 (3/2f )) and Xe atoms is studied throughout the 0.14 to 1.14 kcal/mol (50 to 400 cm −1 ) region, with an overall energy resolution of ∼ 0.03 kcal/mol (13 cm −1 ). We chose the OH-rare gas system because, at higher collision energies, rotationally inelastic collisions have been studied for this system in great detail, both experimentally and theoretically; state-to-state cross-sections and the effects of molecular orientation have been determined (28,29 ). The energy range covered in the present study encompassed the energetic thresholds for inelastic scattering down to the lowest rotational levels of OH.…”

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confidence: 99%

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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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confidence: 73%

mentioning

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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“…Early calculations [17,18] on rotationally inelastic scattering of N 2 molecules with He atoms have shown that resonances occur at low collision energies, but the experimental verification of these predictions was not yet possible. Collisions of OH(X 2 Π) with rare gases have emerged as paradigms of scattering of an open-shell molecule with an atom [13,15,[19][20][21][22][23][24]. The OH-rare gas systems are good candidates for the observation and analysis of resonances in rotationally inelastic collisions because the collision energy can be reduced by Stark deceleration of the OH beam.…”

Section: Introductionmentioning

confidence: 99%

Resonances in rotationally inelastic scattering of OH(X2Π) with helium and neon

Gubbels

Alexander

Dagdigian

et al. 2012

The Journal of Chemical Physics

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We present detailed calculations on resonances in rotationally and spin-orbit inelastic scattering of OH (X 2 Π, j = 3/2, F1, f ) radicals with He and Ne atoms. We calculate new ab initio potential energy surfaces for OH-He, and the cross sections derived from these surfaces compare favorably with the recent crossed beam scattering experiment of Kirste et al. [Phys. Rev. A 82, 042717 (2010)]. We identify both shape and Feshbach resonances in the integral and differential state-tostate scattering cross sections, and we discuss the prospects for experimentally observing scattering resonances using Stark decelerated beams of OH radicals.

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“…Previous studies of inelastic scattering with Ar concentrated mostly on NO, [8][9][10][31][32][33][34][35][36][37][38][39] OH, 18,21,22,24 and HCl, 40 although scattering of a polyatomic molecule with Ar has been explored in the case of NH 3 . 41,42 Molecular nitrogen was previously used as a collider in studies of the inelastic scattering of HCl.…”

Section: Introductionmentioning

confidence: 99%

“…6 This body of work extended the scope of inelastic scattering of labile free radicals, which had previously concentrated on collisions of diatomic radicals with atomic species. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] A recent article by Dagdigian reviewed collisional energy transfer calculations for small hydrocarbon intermediates 26 and highlighted computational studies of integral cross sections for collisions of methylene (CH 2 ) 27,28 and methyl radicals. 5,28,29 The methyl radical is also the first polyatomic free radical to be slowed in a Zeeman decelerator using a pulsed magnetic field, 30 opening up new possibilities to study inelastic and reactive scattering at very low collision energies.…”

Section: Introductionmentioning

confidence: 99%

Rotationally inelastic scattering of methyl radicals with Ar and N2

Tkáč

Stei

Orr-Ewing

et al. 2015

The Journal of Chemical Physics

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Articles you may be interested inThe rotationally inelastic scattering of methyl radical with Ar and N 2 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 N 2 collision partners are strongly forward peaked for all spectroscopic lines measured. For scattering angles below 60 • , the theoretical CD 3 -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. C 2015 AIP Publishing LLC. [http://dx

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Rotationally inelastic collisions of OH(X 2Π)+Ar. I. State-to-state cross sections

Cited by 52 publications

References 24 publications

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

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

Resonances in rotationally inelastic scattering of OH(X2Π) with helium and neon

Rotationally inelastic scattering of methyl radicals with Ar and N2

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