Diffusion on a stepped surface: H and D on Rh[lcub]332[rcub]

Hoogers, Gregor; Lesiak-Orlowska, B.; King, David A.

doi:10.1016/0039-6028(94)00825-6

Cited by 20 publications

(9 citation statements)

References 22 publications

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“…The proposed mechanism is based on the assumption that D atoms stick more strongly than H atoms so that their desorption rate is lower. This isotope effect was observed in various experimental situations (Koehler et al 1988;Hoogers 1995;Amiaud et al 2007). As a result, the residence time of D atoms on grains is expected to be longer than that of H atoms.…”

Section: Astrophysical Contextmentioning

confidence: 85%

Incorporation of stochastic chemistry on dust grains in the Meudon PDR code using moment equations

Petit¹,

Barzel

Biham

et al. 2009

A&A

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Context. Unlike gas-phase reactions, chemical reactions taking place on interstellar dust grain surfaces cannot always be modeled by rate equations. Because of the small grain sizes and low flux, these reactions may exhibit large fluctuations and thus require stochastic methods such as the moment equations. Aims. We evaluate the formation rates of H 2 , HD, and D 2 molecules on dust grain surfaces and their abundances in the gas phase under interstellar conditions. Methods. We incorporate the moment equations into the Meudon PDR code and compare the results with those obtained from the rate equations. Results. We find that within the experimental constraints on the energy barriers for both diffusion and desorption and the density of adsorption sites on the grain surface, H 2 , HD and D 2 molecules can be formed efficiently on dust grains. Conclusions. In a wide range of conditions, the moment equation results agree with those obtained from the rate equations. However, for a range of relatively high grain temperatures, there are significant deviations: the rate equations fail, while the moment equations provide accurate results. The incorporation of the moment equations into the PDR code can be extended to other reactions taking place on grain surfaces.

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Section: Astrophysical Contextmentioning

confidence: 85%

Incorporation of stochastic chemistry on dust grains in the Meudon PDR code using moment equations

Petit¹,

Barzel

Biham

et al. 2009

A&A

View full text Add to dashboard Cite

show abstract

“…The mechanism is based on the assumption that D atoms stick to the surface more strongly than H atoms so that their desorption rate is lower. An isotope effect of this type has been observed in various experimental situations (Koehler et al 1988;Hoogers et al 1995).…”

Section: Introductionmentioning

confidence: 89%

Enhanced production of HD and D₂molecules on small dust grains in diffuse clouds

Lipshtat¹,

Biham²,

Herbst³

2004

Monthly Notices of the Royal Astronomical Society

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Motivated by recent observations of deuterated molecules in the interstellar medium, we examine the production of HD and D 2 molecules on dust grain surfaces. A mechanism for the enhanced production of these deuterated molecules is studied. This mechanism applies on grain surfaces on which D atoms stick more strongly than H atoms, under conditions of low flux and within a suitable range of temperatures. It is shown that under these conditions the production rates of HD and D 2 are greatly enhanced (vs. the H 2 production rate) compared with the expected rates based on the adsorption of gas-phase atomic abundances of D and H. The enhancement in the formation rate of HD is comparable with the enhancement due to gas-phase ion-molecule reactions in diffuse clouds.

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“…By applying laserinduced thermal desorption methods, the diffusion parallel and normal to the step direction was measured. The activation energy for diffusion of H on Rh(332) was found [200] to be 16.1 kJ/mol in the direction parallel to the step and 20.9 kJ/mol normally to it. Such values are somewhat higher than for the similar Rh(111) surface and the results were attributed to the additional energy barrier associated with the step (Schwoebel barrier effect).…”

Section: Influence Of Steps On Rotational-translational Energy Convermentioning

confidence: 95%

“…H 2 /Pt(533) [97], it was shown that the presence of steps may influence the adsorption dynamics inducing a non-monotonic dependence on collision energy (S 0 decreases initially with E i and increases again thereafter). Some authors concentrated on the influence of the step on the rotational-translational energy conversion [175,198], others devoted their efforts to unravel the role of steps in adatom diffusion [199,200].…”

Section: Influence Of Steps On Rotational-translational Energy Convermentioning

confidence: 99%

Bridging the structure gap: Chemistry of nanostructured surfaces at well-defined defects

Vattuone

Savio

Rocca

2008

Surface Science Reports

121

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Diffusion on a stepped surface: H and D on Rh[lcub]332[rcub]

Cited by 20 publications

References 22 publications

Incorporation of stochastic chemistry on dust grains in the Meudon PDR code using moment equations

Incorporation of stochastic chemistry on dust grains in the Meudon PDR code using moment equations

Enhanced production of HD and D₂molecules on small dust grains in diffuse clouds

Bridging the structure gap: Chemistry of nanostructured surfaces at well-defined defects

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Diffusion on a stepped surface: H and D on Rh[lcub]332[rcub]

Cited by 20 publications

References 22 publications

Incorporation of stochastic chemistry on dust grains in the Meudon PDR code using moment equations

Incorporation of stochastic chemistry on dust grains in the Meudon PDR code using moment equations

Enhanced production of HD and D2molecules on small dust grains in diffuse clouds

Bridging the structure gap: Chemistry of nanostructured surfaces at well-defined defects

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Enhanced production of HD and D₂molecules on small dust grains in diffuse clouds