Reply to the Comment on “The ordering of the adsorbed NH3 molecules across the Si dimer rows on the Si(001) surface [Surf. Sci. 602 (2008) L69]”

Koo, Ja−Yong; Kim, Hanchul; Chung, Opti Naguan; Chung, Sukmin

doi:10.1016/j.susc.2008.09.035

Cited by 3 publications

(3 citation statements)

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“…The basic physics would suggest that the NH 2 group would be higher than the H group; the physical height difference in an atomic model matched the measured height difference in STM at −2 V sample bias, and the lone pair on the N atom would appear bright relative to the H atom. However, this interpretation has been disputed [59][60][61].…”

Section: The Appearance In Stmmentioning

confidence: 99%

“…argued [60] that their use of modelling voltages enables the overall contrast between NH 3 fragments and the clean Si to be made correct and that in the −2 V simulations the NH 2 is relatively too bright compared to the Si up atoms. Further, that their assignment of H and NH 2 matches the empty states simulation as well as the filled states.…”

Section: The Appearance In Stmmentioning

confidence: 99%

“…A linear feature without the hydrogen bond is only 0.08 eV worse in energy [52,35] than with one, while the difference between linear and zigzag is around 0.06 eV [69]. Apart from H-bonding interactions, it has been suggested that neighbouring NH 2 groups repel each other, either via steric repulsion, or electrostatic interactions between the lone pair electrons on neighbouring groups [38,59,60]. However, the calculated strengths of these repulsive interactions are probably misleading; the identical positions of the neighbouring NH 2 groups suggests that independent rotation of the two species to a lower-energy structure was not permitted in these calculations.…”

Section: Interactions Between Nh 2 Groups On the Surfacementioning

confidence: 99%

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Competing interactions in molecular adsorption: NH₃on Si(001)

Owen

2009

J. Phys.: Condens. Matter

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Ammonia is a good model system for the study of co-adsorption interactions, including indirect effects such as charge and strain-induced local effects on adsorption sites, and direct interactions such as hydrogen bonding. On the Si(001) surface, it adsorbs molecularly, via a dative bond from the N atom to the down atom of a buckled dimer, and is therefore very sensitive to the local charge conditions. It will then dissociate into -H and -NH(2) groups, adsorbed on the dangling bonds of the Si dimers. The NH(2) groups do not diffuse, so any correlations deriving from interactions during adsorption are preserved, and can be derived by analysis of the arrangements of the NH(2) groups. Hydrogen-bonding interactions are crucial in understanding the behaviour of this system, with significant co-adsorption interactions occurring both along and across rows, outweighing the electrostatic or buckling-related effects. In recent years, there have been several scanning tunnelling microscopy studies and extensive computational modelling of the NH(3) on Si(001) system, attempting to determine a dominant mechanism governing co-adsorption effects. In this review, I will discuss both experimental and theoretical results, make a comparison with similar molecules such as phosphine (PH(3)), and review the different ways in which experimentalists and modellers have approached this complex system.

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Section: The Appearance In Stmmentioning

confidence: 99%

Section: The Appearance In Stmmentioning

confidence: 99%