>Nightscream: Remove bare external link per WP:NOT/WP:CS, rm "interesting" per WP:TONE/WP:NPOV/WP:NOR.

2020-12-20T20:16:40Z

Remove bare external link per WP:NOT/WP:CS, rm "interesting" per WP:TONE/WP:NPOV/WP:NOR.

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[[File:Nanomesh 3D.JPG|thumb|Perspective view of nanomesh, whose structure ends at the back of the figure. The distance between two pore centers is 3.2nm, and the pores are 0.05nm deep.]]

The '''nanomesh''' is an [[inorganic]] nanostructured two-dimensional material, similar to [[graphene]]. It was discovered in 2003 at the [[University of Zurich]], Switzerland.<ref name="corso04">{{cite journal | author = M. Corso | title = Boron Nitride Nanomesh | journal=Science | volume = 303 |pages = 217–220 |doi = 10.1126/science.1091979 | date = 2004 | pmid = 14716010 | issue = 5655|bibcode = 2004Sci...303..217C | display-authors = 4 | last2 = Auwärter | first2 = Willi | last3 = Muntwiler | first3 = Matthias | last4 = Tamai | first4 = Anna | last5 = Greber | first5 = Thomas | last6 = Osterwalder | first6 = Jürg | s2cid = 11964344 }}</ref>

It consists of a single layer of [[boron]] (B) and [[nitrogen]] (N) atoms, which forms by [[self-assembly]] into a highly regular mesh after high-temperature exposure of a clean [[rhodium]]<ref name="corso04"/> or [[ruthenium]]<ref name="goriachko07">{{cite journal | author = A. Goriachko | title = Self-assembly of a hexagonal boron nitride nanomesh on Ru(0001)| journal=Langmuir | volume = 23 |pages = 2928–2931 |doi = 10.1021/la062990t | date = 2007 | pmid = 17286422 | display-authors = 4 | last2 = He | first2 = Y | last3 = Knapp | first3 = M | last4 = Over | first4 = H | last5 = Corso | first5 = M | last6 = Brugger | first6 = T | last7 = Berner | first7 = S | last8 = Osterwalder | first8 = J | last9 = Greber | first9 = T | issue = 6}}</ref> surface to [[borazine]] under [[ultra-high vacuum]].

The nanomesh looks like an assembly of hexagonal pores<ref name="nomenc">In the literature different words referring to similar concepts can be found. Below is a summary of them:
* ''Pores, apertures, holes:'' areas of the nanomesh laying the closest to the underlying substrate due to a strong attraction. They form depressions, which are 0.05 nm deep and have a hexagonal shape.
* ''Wires:'' areas of the nanomesh referring to the border of the pores, which lay the farer away to the underlying substrate and therefore represent the upper part of the nanomesh.</ref> (see right image) at the [[nanometer]] (nm) scale. The distance between two pore centers is only 3.2 nm, whereas each pore has a diameter of about 2 nm and is 0.05 nm deep. The lowest regions bind strongly to the underlying metal, while the wires<ref name="nomenc"/> (highest regions) are only bound to the surface through strong cohesive forces within the layer itself.

The [[boron nitride]] nanomesh is not only stable under vacuum,<ref name="corso04"/> air<ref name="bunk07">{{cite journal | author = O. Bunk | title = Surface X-ray diffraction study of boron-nitride nanomesh in air | journal=Surf. Sci. | volume = 601 |pages = L7–L10 |doi = 10.1016/j.susc.2006.11.018| date = 2007 | display-authors = 4 | last2 = Corso | first2 = M | last3 = Martoccia | first3 = D | last4 = Herger | first4 = R | last5 = Willmott | first5 = P | last6 = Patterson | first6 = B | last7 = Osterwalder | first7 = J | last8 = Vanderveen | first8 = J | last9 = Greber | first9 = T | issue = 2|bibcode = 2007SurSc.601L...7B | url = https://www.dora.lib4ri.ch/psi/islandora/object/psi%3A18158 }}</ref> and some liquids,<ref name="berner07">{{cite journal | author = S. Berner | author2 = M. Corso | display-authors = etal | title = Boron Nitride Nanomesh: Functionality from a Corrugated Monolayer | journal=Angew. Chem. Int. Ed. | volume = 46 |pages = 5115–5119 |doi = 10.1002/anie.200700234 | date = 2007 | pmid = 17538919 | issue = 27}}</ref><ref name="widmer07">{{cite journal | author = R. Widmer | title = Electrolytic in situ STM investigation of h-BN-Nanomesh | journal=Electrochem. Commun. | volume = 9 |pages = 2484–2488 |doi = 10.1016/j.elecom.2007.07.019| date = 2007 | display-authors = 4 | last2 = Berner | first2 = S | last3 = Groning | first3 = O | last4 = Brugger | first4 = T | last5 = Osterwalder | first5 = J | last6 = Greber | first6 = T | issue = 10}}</ref> but also up to temperatures of 796 °C (1070 K).<ref name="corso04"/> In addition it shows the extraordinary ability to trap [[molecules]]<ref name="berner07"/> and metallic [[cluster (physics)|clusters]],<ref name="goriachko07"/> which have similar sizes to the nanomesh pores, forming a well-ordered array. These characteristics may provide applications of the material in areas like, [[surface functionalisation]], [[spintronics]], [[quantum computing]] and data storage media like [[hard drive]]s.

==Structure==
[[Image:Cross section nanomesh.jpg|thumb|300px|Cross-section of nanomesh on rhodium showing pore and wire regions]]
h-BN nanomesh is a single sheet of [[boron nitride#Hexagonal boron nitride|hexagonal boron nitride]], which forms on substrates like [[rhodium]] Rh[[miller index|(111)]] or [[ruthenium]] Ru[[miller index|(0001)]] [[crystal]]s by a [[self-assembly]] process.

The [[unit cell]] of the h-BN nanomesh consists of 13x13 BN or 12x12 Rh atoms with a [[lattice constant]] of 3.2 nm. In a cross-section it means that 13 boron or nitrogen atoms are sitting on 12 rhodium atoms. This implies a modification of the relative positions of each BN towards the substrate atoms within a unit cell, where some [[chemical bond|bonds]] are more attractive or repulsive than other (site selective bonding), what induces the corrugation of the nanomesh (see right image with pores and wires).

The nanomesh corrugation amplitude of 0.05 nm causes a strong effect on the [[electronic structure]], where two distinct BN regions are observed. They are easily recognized in the lower right image, which is a [[scanning tunneling microscope|scanning tunneling microscopy]] (STM) measurement, as well as in the lower left image representing a theoretical calculation of the same area. A strongly bounded region assigned to the pores is visible in blue in the left image below (center of bright rings in the right image) and a weakly bound region assigned to the wires appears yellow-red in the left image below (area in-between rings in the right image).
{|
|[[Image:BNmodel-2.JPG|400px|Theoretical calculation of nanomesh N height relative to the underlying substrate. The image show a similar spot as the previous STM image.]]
||
   
| style="vertical-align:bottom;"| [[Image:STMnm-2.JPG|177px|Boron Nitride Nanomesh observed by STM at 77K.]]
||
   
|| The right image shows the boron nitride nanomesh measured by STM at 77K, where each "ball" represents one N atom. The center of each ring corresponds to the center of the pores.
The left image is the theoretical calculation of the same area, where the N height relative to the underlying substrate is given. The exact arrangement of Rh, N and B atoms is given for three different areas (blue: pores, yellow-red: wires).
|}

See <ref name="corso04"/><ref name="goriachko07"/><ref name="bunk07"/><ref name="berner07"/><ref name="laskowski07">{{cite journal | author = R. Laskowski | title = Single layer model of the h-BN nanomesh on the Rh(111) surface | journal=Phys. Rev. Lett. | volume = 98 |pages = 106'802 |doi = 10.1103/PhysRevLett.98.106802 | date = 2007 | bibcode=2007PhRvL..98j6802L | issue = 10| last2 = Blaha | first2 = Peter | last3 = Gallauner | first3 = Thomas | last4 = Schwarz | first4 = Karlheinz | pmid = 17358554 }}</ref> for more details.

==Properties==
[[Image:ncNanomesh.gif|thumb|Naphthalocyanine molecules evaporated onto the nanomesh. They only adsorb in pores, forming a well-defined pattern.]]

The nanomesh is stable under a wide range of environments like air, water and [[electrolyte]]s among others. It is also temperature resistant since it does not decompose in temperatures up to 1275K under a vacuum. In addition to these exceptional stabilities, the nanomesh shows the extraordinary ability to act as a scaffold for metallic nano[[cluster (physics)|clusters]] and to trap [[molecule]]s forming a well-ordered array.

In the case of [[gold]] (Au), its evaporation on the nanomesh leads to formation of well-defined round Au nanoparticles, which are centered at the nanomesh pores.

The [[scanning tunneling microscope|STM]] figure on the right shows [[Naphthalocyanine]] (Nc) molecules, which were [[chemical vapor deposition|vapor-deposited]] onto the nanomesh. These planar molecules have a diameter of about 2 nm, whose size is comparable to that of the nanomesh pores (see upper inset). It is spectacularly visible how the molecules form a well-ordered array with the periodicity of the nanomesh (3.22 nm). The lower inset shows a region of this substrate with higher resolution, where individual molecules are trapped inside the pores. In addition, the molecules seem to keep their native [[Chemical structure|conformation]], what means that their functionality is kept, which is nowadays a challenge in [[nanoscience]].

Such systems with wide spacing between individual molecules/clusters and negligible [[chemical bond#Intermolecular bonding|intermolecular interactions]] might be interesting for applications such as [[molecular electronics]] and [[flash memory|memory elements]], in [[photochemistry]] or in optical devices.

See <ref name="goriachko07"/><ref name="berner07"/><ref name="widmer07"/> for more detailed information.

==Preparation and analysis==

[[Image:BorazineDecomp.jpg|thumb|Decomposition of borazine on transition metal surfaces.]]
Well-ordered nanomeshes are grown by [[thermal decomposition]] of [[borazine]] (HBNH)3, a colorless substance that is liquid at room temperature. The nanomesh results after exposing the atomically clean [[rhodium|Rh]][[miller index|(111)]] or [[ruthenium|Ru]][[miller index|(0001)]] surface to borazine by [[chemical vapor deposition]] (CVD).

The substrate is kept at a temperature of 796 °C (1070 K) when borazine is introduced in the vacuum chamber at a dose of about 40 L (1 Langmuir = 10−6 [[Pressure units|torr]] sec). A typical borazine vapor pressure inside the ultrahigh vacuum chamber during the exposure is 3x10−7 [[Pressure units|mbar]].

After cooling down to room temperature, the regular mesh structure is observed using different experimental techniques. [[scanning tunneling microscope|Scanning tunneling microscopy]] (STM) gives a direct look on the local real space structure of the nanomesh, while [[low-energy electron diffraction|low energy electron diffraction]] (LEED) gives information about the surface structures ordered over the whole sample. [[ultra-violet photoelectron spectroscopy|Ultraviolet photoelectron spectroscopy]] (UPS) gives information about the electronic states in the outermost atomic layers of a sample, i.e. electronic information of the top substrate layers and the nanomesh.

== See also ==
{{Portal|Science|Technology}}

==Other forms==
[[chemical vapor deposition|CVD]] of [[borazine]] on other substrates has not led so far to the formation of a corrugated nanomesh. A flat BN layer is observed on [[nickel]]<ref>{{cite journal | author = T. Greber | title = Single layer hexagonal boron nitride films on Ni(110) | journal=E-J. Surf. Sci. Nanotech. | volume = 4 |page = 410 |url = http://joi.jlc.jst.go.jp/JST.JSTAGE/ejssnt/2006.410 | date = 2006 | doi = 10.1380/ejssnt.2006.410 | format = – [https://scholar.google.co.uk/scholar?hl=en&lr=&q=author%3A+intitle%3ASingle+layer+hexagonal+boron+nitride+films+on+Ni%28110%29&as_publication=e-J.+Surf.+Sci.+Nanotech&as_ylo=2006&as_yhi=2006&btnG=Search Scholar search]| display-authors = 4| last2 = Brandenberger | first2 = Louis | last3 = Corso | first3 = Martina | last4 = Tamai | first4 = Anna | last5 = Osterwalder | first5 = Jürg | doi-access = free }}</ref> and [[palladium]],<ref>{{cite journal | author = M. Corso | title = h-BN on Pd(110): a tunable system for selfassembled nanostructures? | journal=Surf. Sci. | volume = 577 |pages = L78 |doi = 10.1016/j.susc.2005.01.015 | date = 2005 | issue = 2–3|bibcode = 2005SurSc.577L..78C | last2 = Greber | first2 = Thomas | last3 = Osterwalder | first3 = Jürg }}</ref><ref>{{cite journal | author = M. Morscher | title = Formation of single layer h-BN on Pd(111) | journal=Surf. Sci. | volume = 600 |pages = 3280–3284 |doi = 10.1016/j.susc.2006.06.016 | date = 2006 | issue = 16|bibcode = 2006SurSc.600.3280M | last2 = Corso | first2 = M. | last3 = Greber | first3 = T. | last4 = Osterwalder | first4 = J. }}</ref> whereas stripped structures appear on [[molybdenum]]<ref>{{cite journal | author = M. Allan | title = Tunable self-assembly of one-dimensional nanostructures with orthogonal directions | journal=Nanoscale Res. Lett. | volume = 2 |pages = 94–99 |doi = 10.1007/s11671-006-9036-2 | date = 2007 | issue=2|bibcode = 2007NRL.....2...94A | display-authors = 4 | last2 = Berner | first2 = Simon | last3 = Corso | first3 = Martina | last4 = Greber | first4 = Thomas | last5 = Osterwalder | first5 = Jürg | pmc = 3245566 }}</ref> instead.

==References and notes==
{{Reflist}}

==Other links==
http://www.nanomesh.ch

http://www.nanomesh.org

[[Category:Two-dimensional nanomaterials]]
[[Category:Self-organization]]
[[Category:Thin films]]
[[Category:Nitrides]]
[[Category:Boron compounds]]
[[Category:III-V compounds]]
[[Category:Transition metals]]
[[Category:NASA spin-off technologies]]

Nanomesh - Revision history

>Nightscream: Remove bare external link per WP:NOT/WP:CS, rm "interesting" per WP:TONE/WP:NPOV/WP:NOR.