Rotationally inelastic scattering and potential calculations for Ne + CH<sub>4</sub>

Buck, U.; Kohlhase, A.; Secrest, Don; Phillips, Timothy R.; Scoles, G.; Grein, Friedrich

doi:10.1080/00268978500102001

Cited by 45 publications

(24 citation statements)

References 40 publications

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“…Previous investigation showed that after such an expansion, 31 % of the methane molecules were in jCH4=0, 56% in jCH4=1 and 13% in jCH4=2. 45 In addition, it has been reported that the rotational temperature of CH4 molecules in a neat methane molecular beam was estimated to be about 9 K from the measured speed distribution. 32,46 Because of the crossing timescale of several microseconds in the intersection region of the two molecular beams, the detection efficiency of the scattered products depended on their speeds in the laboratory frame.…”

Section: Experimental Methodsmentioning

confidence: 99%

Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH₄

et al. 2019

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Using a combination of velocity-map imaging and resonance-enhanced multi-photon 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 (j′NO) and spin-orbit () 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 j′NO =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 anti-correlation in this bimolecular scattering.

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Section: Experimental Methodsmentioning

confidence: 99%

Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH₄

et al. 2019

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“…The first interaction potentials for the Ne-CH 4 complex were proposed about twenty years ago by Udo Buck et al 21 and Michael J. O'Loughlin et al 22 These latter authors proposed an effective spherical potential for the complex, with a well depth of 209 AE 13 mE h at the C-Ne internuclear separation of 6.95 bohr, fitted by inversion of differential rotationally inelastic cross sections (DCS) obtained from crossed beam experiments. Buck et al 21 combined theoretical computations and available experimental data to define a potential-from now on referred to as BUCK-which includes also two anisotropy terms. They defined an analytical expression of the PES with a single adjustable parameter, fitted such as to maximize the agreement between measured rotational cross sections at 88 meV and coupled states computations.…”

Section: The Ne-ch 4 Systemmentioning

confidence: 99%

“…This article is organized as follows: in the next section we report a summarized overview on the literature concerning the Ne-CH 4 system; we then present an exhaustive survey of the MO-VB approach, describe the details of our theoretical computations, and report on the fitting of the resulting data to define the analytical potentials. The features of the PES are then discussed and compared to the one originally proposed by Buck et al 21 The last section contains conclusions and perspectives.…”

Section: Introductionmentioning

confidence: 99%

Application of valence-bond techniques to the study of weakly bound complexes. The potential energy surface of the Ne–CH₄system

Cargnoni

Mella

Raimondi

2007

Phys. Chem. Chem. Phys.

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We present a comprehensive survey of the Molecular Orbital-Valence Bond (MO-VB) method, a theoretical scheme developed within the framework of the Valence Bond theory to deal with weakly bound intermolecular complexes. According to the MO-VB, the wavefunction of the system is expressed as a truncated non-orthogonal Configuration Interaction expansion, which is size extensive and a priori free of basis set superposition error. We report on the recent developments of the method, which extend the range of application of the MO-VB to intermolecular complexes with a quite large number of correlated electrons, showing that VB-based methods are nowadays a valid alternative to Molecular Orbital approaches also in this field. The MO-VB has been applied to study extensively the Ne-CH(4) complex, and compared with the more standard MP4 and CCSD(T) results. We determined two analytical Potential Energy Surfaces (PES) for this system, computed at MO-VB and MP4 level, which represent the first ones coming entirely from ab initio computations. The features of our potentials are discussed, and compared to the single analytical potential which includes the anisotropy available in the literature, determined about twenty years ago by Udo Buck and co-workers using a semiempirical approach [U. Buck, A. Kolhase, D. Secrest, T. Phillips, G. Scoles and F. Grein, Mol. Phys., 1985, 55, 1233]. The differences among the three PES are quite relevant, and are due to play a relevant role in the theoretical simulations of the dynamical properties of the Ne-CH(4) system.

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“…The first scattering measurements for the spherical top CH4 + He, Ne, and Ar were performed by Buck and coworkers [127][128][129]176, 1771 in a similar experimental arrangement. For CHI + He, the final statesjfare partially resolved in the time-of-flight mass spectrometer, enabling the extraction of state-to-state cross-sections for some jf.…”

Section: Diflerential Cross-section Measurementsmentioning

confidence: 99%

Experimental measurements of state resolved, rotationally inelastic energy transfer

Schiffman

Chandler

1995

International Reviews in Physical Chemistry

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A great deal of experimental effort has been put toward measurements of integral and differential, state-to-state cross-sections for rotationally inelastic energy transfer. Throughout the years measurements in thermal gas cells, and in crossed molecular beams, have been performed at increasingly impressive levels of quantum state detail. Because the term 'rotational energy transfer' can include collisional interchange among nuclear rotational states, magnetic sublevels, electron spin and orbital quantum levels, and vibrational angular momentum states, and can also include rotation-translationhibration energy transfer, the field is an expansive one. In this review an array of experimental studies is encapsulated, including discussion of quantum-state propensities, their known or speculative physical origins, and the success or failure of simple energy transfer models. Discussion of progress toward the development of accurate, jntermolecular potential energy surfaces, and the results of classical or quantum scattering calculations, accompanies the overview of experimental work.

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Rotationally inelastic scattering and potential calculations for Ne + CH₄

Cited by 45 publications

References 40 publications

Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH₄

Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH₄

Application of valence-bond techniques to the study of weakly bound complexes. The potential energy surface of the Ne–CH₄system

Experimental measurements of state resolved, rotationally inelastic energy transfer

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Rotationally inelastic scattering and potential calculations for Ne + CH4

Cited by 45 publications

References 40 publications

Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH4

Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH4

Application of valence-bond techniques to the study of weakly bound complexes. The potential energy surface of the Ne–CH4system

Experimental measurements of state resolved, rotationally inelastic energy transfer

Contact Info

Product

Resources

About

Rotationally inelastic scattering and potential calculations for Ne + CH₄

Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH₄

Observation of Rainbows in the Rotationally Inelastic Scattering of NO with CH₄

Application of valence-bond techniques to the study of weakly bound complexes. The potential energy surface of the Ne–CH₄system