Direct measurement of the energy release and final molecular axis orientation in dissociative molecular scattering at surfaces

Rechtien, J.H.; Harder, R.; Herrmann, G.; Nesbitt, A.; Tellioglu, K.; Snowdon, K.J.

doi:10.1016/0039-6028(93)90617-s

Cited by 20 publications

(5 citation statements)

References 19 publications

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“…This approach has recently been extended to gas/ surface scattering, where many studies have focused on the dynamics of inelastic scattering and trapping/desorption processes under thermal conditions. [38][39][40][41][42][43][44][45][46][47] At keV beam energies and glancing incidence angles, Snowdon 48,49 and Los 50 have observed the final relative velocity vector of dissociatively scattered diatoms. This paper describes the first experiment to scatter aligned molecular ions on a well-characterized surface.…”

Section: Introductionmentioning

confidence: 99%

Scattering aligned NO+ on Ag(111): The effect of internuclear-axis direction on NO− and O− product formation

Greeley

Martin

Morris

et al. 1995

The Journal of Chemical Physics

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Hyperthermal energy reactions of NO ϩ with Ag͑111͒ were studied as a function of collision energy and the incident diatom's internuclear-axis direction. Laser photoselection via ͑1ϩ1Ј͒ resonance enhanced multiphoton ionization ͑REMPI͒ prepared an aligned distribution of NO ϩ ͑X 1 ⌺ ϩ , E trans , vϭ0, J͒ prior to the molecules impact with the surface. The emergence of scattered O Ϫ products was enhanced when NO ϩ approached the surface with an ''end-on'' rather than a ''side-on'' orientation. Moreover, the magnitude of the reaction's alignment preference increased with decreasing collision energy. The appearance threshold for O Ϫ was approximately 20 eV. Classical trajectory calculations demonstrated that these results are consistent with a collision-induced dissociation mechanism mediated by both vibrational and rotational excitation upon impact. Reorientation of the internuclear axis during the collision drastically affects the simulated dissociation dynamics. No alignment preference for scattered NO Ϫ emergence could be discerned from the experiments. As a complement, the angular momentum mechanics are provided to predict the internuclear-axis distribution of ions created via two-photon REMPI.

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Section: Introductionmentioning

confidence: 99%

Scattering aligned NO+ on Ag(111): The effect of internuclear-axis direction on NO− and O− product formation

Greeley

Martin

Morris

et al. 1995

The Journal of Chemical Physics

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“…In this context, the known method of generating a supersonic molecular beam 20,21 typically gives hyperthermal H 2 with a kinetic energy and beam current too low for practical selective C-H cleavage. The method of neutralizing a hyperthermal H 2 + beam 22 is also impractical because of its flux limitation due to space-charge-induced spreading of a low energy ion beam as explained earlier. Although collision processes involving H 2 have been studied for many decades, 2,3,8-10,14-16,20-26 these studies have never explored methods for the generation of a high flux of hyperthermal H 2 to treat a practically large sample-area.…”

Section: Engineering Design Of a High Flux Of Hyperthermal Hmentioning

confidence: 99%

Cleaving C–H bonds with hyperthermal H₂: facile chemistry to cross-link organic molecules under low chemical- and energy-loads

et al. 2014

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A facile method for cross-linking organic molecules has been developed by computational modeling, instrumentation design, and experimental research. Briefly, organic molecules are hit by H 2 with controllable kinetic energy in our novel apparatus where a high flux of hyperthermal H 2 is generated. When a C-H bond of the organic molecule is hit by H 2 at about 20 eV, efficient kinematic energy-transfer in the H 2 →H collision facilitates the C-H dissociation with nearly 100% reaction probability. When H 2 hits other atoms which are by nature much heavier than H 2 , mass disparity bars effective energy transfer and this both blocks undesirable bond dissociation and reduces unnecessary energy wastage. The recombination of the carbon radicals generated by the C-H cleavage efficiently completes the production of C-C cross-links at room temperature with no additional energy/chemicals requirements. In addition to these green chemistry merits, this new method is better than other cross-linking techniques which rely on prerequisite reactions to add cross-linkers to the organic molecules or additional reactants and additives.These promising features are validated by several cross-linking trials which demonstrate desirable mechanical, electrical, chemical, and biochemical changes while inducing no undesirable damage of chemical functionalities in the original molecules. † Electronic supplementary information (ESI) available: Additional data to further enrich the following aspects of scientific explanation and discussion: applications of HHIC, methods and materials, estimation of C-H and C-C bond cleavage thresholds and HHIC reaction rate, and spectroscopic data. See

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“…A simulation of scattering from a truly rigid planar surface gives average initial orientations of 60 • and 30 • respectively [86], illustrating that for high surface-parallel velocities and glancing incidence, surfaces appear to lose their atomic structure and become 'flat'. [104,107,108]. The magnitude v of the relative-velocity vector defines the kinetic energy ε = 1 2 µv 2 in the centre of mass of the molecule, where µ is its reduced mass.…”

Section: Collisional Dissociation Mechanismsmentioning

confidence: 99%

“…However, as pointed out by Imke et al [106] and Schins et al [104], the interaction of the fragments with the surface following charge transfer cannot in general be neglected. At particle velocities where a measurement of θ is experimentally feasible using the technique of translational spectroscopy ( [104,107,108] and figure 12), strong dissipative (friction-like) forces significantly modify the particle trajectories (figure 13).…”

Section: Electronic Dissociation Mechanismsmentioning

confidence: 99%

“…Figure 12. A measurement of the mean velocity, impact position, and arrival time difference of the dissociation fragments of a diatomic molecule defines their relative velocity v = v 2 − v 1 to high accuracy[104,107,108]. The magnitude v of the relative-velocity vector defines the kinetic energy ε = 1 2 µv 2 in the centre of mass of the molecule, where µ is its reduced mass.…”

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Orientation in molecule - surface interactions

Heinzmann

Holloway

Kleyn

et al. 1996

J. Phys.: Condens. Matter

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The role of the orientation of a molecule in its interaction with a surface is examined for a number of cases. At first the determination of the static orientation of a molecule at the surface is discussed. A dependence of the orientation on state and coverage is found for O 2 molecules adsorbed on Ag(110). The orientation dependence of NO in chemisorption, displacement reactions, and chemical reactions is discussed. Rotational excitation of NO in collisions with surfaces is shown to exhibit a strong orientation dependence. Dissociative chemisorption of hydrogen molecules is found to depend on the initial orientation of the molecule. Finally, in dissociative collisions of fast molecules with surfaces the role of the initial orientation is examined and the final orientation of the molecular axis is determined. Several mechanisms for molecular dissociation are discussed.

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Direct measurement of the energy release and final molecular axis orientation in dissociative molecular scattering at surfaces

Cited by 20 publications

References 19 publications

Scattering aligned NO+ on Ag(111): The effect of internuclear-axis direction on NO− and O− product formation

Scattering aligned NO+ on Ag(111): The effect of internuclear-axis direction on NO− and O− product formation

Cleaving C–H bonds with hyperthermal H₂: facile chemistry to cross-link organic molecules under low chemical- and energy-loads

Orientation in molecule - surface interactions

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Direct measurement of the energy release and final molecular axis orientation in dissociative molecular scattering at surfaces

Cited by 20 publications

References 19 publications

Scattering aligned NO+ on Ag(111): The effect of internuclear-axis direction on NO− and O− product formation

Scattering aligned NO+ on Ag(111): The effect of internuclear-axis direction on NO− and O− product formation

Cleaving C–H bonds with hyperthermal H2: facile chemistry to cross-link organic molecules under low chemical- and energy-loads

Orientation in molecule - surface interactions

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Cleaving C–H bonds with hyperthermal H₂: facile chemistry to cross-link organic molecules under low chemical- and energy-loads