Editing Surface science

{{short description|Study of physical and chemical phenomena that occur at the interface of two phases}}
{{for|the journal|Surface Science (journal)}}

[[Image:Selfassembly Organic Semiconductor Trixler LMU.jpg|250px|thumb|[[Scanning tunneling microscope|STM]] image of a [[quinacridone]] [[adsorbate]]. The [[self-assembly|self-assembled]] [[supramolecular]] chains of the [[organic semiconductor]] are adsorbed on a [[graphite]] surface.]]
'''Surface science''' is the study of [[physics|physical]] and [[chemistry|chemical]] phenomena that occur at the [[interface (chemistry)|interface]] of two [[phase (matter)|phases]], including [[solid]]–[[liquid]] interfaces, solid–[[gas]] interfaces, solid–[[vacuum]] interfaces, and [[liquid]]–[[gas]] interfaces. It includes the fields of ''[[surface chemistry]]'' and ''[[surface physics]]''.<ref>{{cite book | last=Prutton | first=Martin | title=Introduction to Surface Physics
| publisher=Oxford University Press | date=1994 | isbn=978-0-19-853476-1 }}</ref> Some related practical applications are classed as [[surface engineering]]. The science encompasses concepts such as [[heterogeneous catalysis]], [[semiconductor device fabrication]], [[fuel cell]]s, [[self-assembled monolayer]]s, and [[adhesive]]s. Surface science is closely related to [[interface and colloid science]].<ref>{{cite book | last=Luklema | first=J. | title=Fundamentals of Interface and Colloid Science | publisher=Academic Press | date=1995–2005 | volume=1–5 }}</ref> Interfacial chemistry and physics are common subjects for both. The methods are different. In addition, interface and colloid science studies [[macroscopic]] [[phenomena]] that occur in [[heterogeneous]] systems due to peculiarities of interfaces.

==History==
The field of surface chemistry started with [[heterogeneous catalysis]] pioneered by [[Paul Sabatier (chemist)|Paul Sabatier]] on [[hydrogenation]] and [[Fritz Haber]] on the [[Haber process]].<ref name=Nobel>{{cite web | last=Wennerström | first=Håkan |author2=Lidin, Sven  | title=''Scientific Background on the Nobel Prize in Chemistry 2007 Chemical Processes on Solid Surfaces''  | url=https://www.nobelprize.org/nobel_prizes/chemistry/laureates/2007/advanced-chemistryprize2007.pdf }}</ref> [[Irving Langmuir]] was also one of the founders of this field, and the scientific journal on surface science, ''[[Langmuir (journal)|Langmuir]]'', bears his name. The [[Langmuir equation|Langmuir adsorption equation]] is used to model monolayer adsorption where all surface adsorption sites have the same affinity for the adsorbing species and do not interact with each other. [[Gerhard Ertl]] in 1974 described for the first time the adsorption of [[hydrogen]] on a [[palladium]] surface using a novel technique called [[Low-energy electron diffraction|LEED]].<ref>{{cite journal | last=Conrad | first=H. | author2=Ertl, G. | author2-link=Gerhard Ertl | author3=Latta, E.E. | title=Adsorption of hydrogen on palladium single crystal surfaces | journal=Surface Science | volume=41 | issue=2 | pages=435–446 | date=February 1974 | doi=10.1016/0039-6028(74)90060-0 |bibcode = 1974SurSc..41..435C }}</ref> Similar studies with [[platinum]],<ref>{{cite journal | last=Christmann | first=K. | author2=Ertl, G. | author2-link=Gerhard Ertl | author3=Pignet, T. | title=Adsorption of hydrogen on a Pt(111) surface | journal=Surface Science | volume=54 | issue=2 | pages=365–392 | date=February 1976 | doi=10.1016/0039-6028(76)90232-6|bibcode = 1976SurSc..54..365C }}</ref> [[nickel]],<ref>{{cite journal | last=Christmann | first=K. | author2=Schober, O. | author3=Ertl, G. | author3-link=Gerhard Ertl | author4=Neumann, M. | title=Adsorption of hydrogen on nickel single crystal surfaces | journal=[[The Journal of Chemical Physics]] | volume=60 | issue=11 | pages=4528–4540  | date=June 1, 1974 | doi=10.1063/1.1680935|bibcode = 1974JChPh..60.4528C }}</ref><ref>{{cite journal | last=Christmann | first=K. | author2=Behm, R. J. | author3=Ertl, G. | author3-link=Gerhard Ertl | author4=Van Hove, M. A. | author5=Weinberg, W. H. | title=Chemisorption geometry of hydrogen on Ni(111): Order and disorder | journal=[[The Journal of Chemical Physics]] | date=May 1, 1979 | volume=70 | issue=9 | pages=4168–4184 | doi=10.1063/1.438041|bibcode = 1979JChPh..70.4168C }}</ref> and [[iron]]<ref>{{cite journal | last=Imbihl | first=R. |author2=Behm, R. J. |author3=Christmann, K. |author4=Ertl, G. |author4-link=Gerhard Ertl |author5=Matsushima, T. 
| title=Phase transitions of a two-dimensional chemisorbed system: H on Fe(110) | journal=Surface Science | volume=117 | issue=1 | date=May 2, 1982 | pages=257–266 |  doi=10.1016/0039-6028(82)90506-4|bibcode = 1982SurSc.117..257I }}</ref> followed. Most recent developments in surface sciences include the 2007 [[Nobel prize of Chemistry]] winner [[Gerhard Ertl]]'s advancements in surface chemistry, specifically
his investigation of the interaction between carbon monoxide molecules and platinum surfaces.

==Chemistry{{anchor|Surface chemistry}}==
Surface chemistry can be roughly defined as the study of chemical reactions at interfaces.  It  is closely related to [[surface engineering]], which aims at modifying the chemical composition of a surface by incorporation of selected elements or [[functional group]]s that produce various desired effects or improvements in the properties of the surface or interface. Surface science is of particular importance to the fields of [[heterogeneous catalysis]], [[electrochemistry]], and [[geochemistry]].

===Catalysis===
The adhesion of gas or liquid molecules to the surface is known as [[adsorption]]. This can be due to either [[chemisorption]] or [[physisorption]], and the strength of molecular adsorption to a catalyst surface is critically important to the catalyst's performance (see [[Sabatier principle]]). However, it is difficult to study these phenomena in real catalyst particles, which have complex structures. Instead, well-defined [[single crystal]] surfaces of catalytically active materials such as [[platinum]] are often used as model catalysts. Multi-component materials systems are used to study interactions between catalytically active metal particles and supporting oxides; these are produced by growing ultra-thin films or particles on a single crystal surface.<ref>{{Cite journal | doi=10.1103/PhysRevB.81.241416| bibcode=2010PhRvB..81x1416F| title=Particle-size dependent heats of adsorption of CO on supported Pd nanoparticles as measured with a single-crystal microcalorimeter| year=2010| last1=Fischer-Wolfarth| first1=Jan-Henrik| last2=Farmer| first2=Jason A.| last3=Flores-Camacho| first3=J. Manuel| last4=Genest| first4=Alexander| last5=Yudanov| first5=Ilya V.| last6=Rösch| first6=Notker| last7=Campbell| first7=Charles T.| last8=Schauermann| first8=Swetlana| last9=Freund| first9=Hans-Joachim| journal=Physical Review B| volume=81| issue=24| pages=241416| hdl=11858/00-001M-0000-0011-29F8-F| hdl-access=free}}</ref>

Relationships between the composition, structure, and chemical behavior of these surfaces are studied using [[ultra-high vacuum]] techniques, including adsorption and [[Thermal desorption spectroscopy|temperature-programmed desorption]] of molecules, [[scanning tunneling microscopy]], [[low energy electron diffraction]], and [[Auger electron spectroscopy]]. Results can be fed into chemical models or used toward the [[rational design]] of new catalysts. Reaction mechanisms can also be clarified due to the atomic-scale precision of surface science measurements.<ref>{{Cite journal |doi = 10.1016/j.cattod.2011.08.033|title = Scanning tunneling microscopy evidence for the Mars-van Krevelen type mechanism of low temperature CO oxidation on an FeO(111) film on Pt(111)|year = 2012|last1 = Lewandowski|first1 = M.|last2 = Groot|first2 = I.M.N.|last3 = Shaikhutdinov|first3 = S.|last4 = Freund|first4 = H.-J.|journal = Catalysis Today|volume = 181|pages = 52–55|hdl = 11858/00-001M-0000-0010-50F9-9|hdl-access = free}}</ref>

===Electrochemistry===
Electrochemistry is the study of processes driven through an applied potential at a solid–liquid or liquid–liquid interface. The behavior of an electrode–electrolyte interface is affected by the distribution of ions in the liquid phase next to the interface forming the [[electrical double layer]]. Adsorption and desorption events can be studied at atomically flat single-crystal surfaces as a function of applied potential, time and solution conditions using [[scanning probe microscopy|spectroscopy, scanning probe microscopy]]<ref>{{Cite journal |doi = 10.1021/cr960067y|pmid = 11851445|title = Electrochemical Applications ofin Situ ''Scanning'' Probe Microscopy|year = 1997|last1 = Gewirth|first1 = Andrew A.|last2 = Niece|first2 = Brian K.|journal = Chemical Reviews|volume = 97|issue = 4|pages = 1129–1162}}</ref> and [[X-ray crystal truncation rod|surface X-ray scattering]].<ref>{{Cite journal | doi=10.1016/S0013-4686(02)00223-2| title=Applications of surface X-ray scattering to electrochemistry problems| year=2002| last1=Nagy| first1=Zoltán| last2=You| first2=Hoydoo| journal=Electrochimica Acta| volume=47| issue=19| pages=3037–3055| url=https://zenodo.org/record/1259573}}</ref><ref>{{Cite journal|date=2016-11-01|title=Surface X-ray diffraction studies of single crystal electrocatalysts|journal=Nano Energy|language=en|volume=29|pages=378–393|doi=10.1016/j.nanoen.2016.05.043|issn=2211-2855|last1=Gründer|first1=Yvonne|last2=Lucas|first2=Christopher A.|doi-access=free}}</ref> These studies link traditional electrochemical techniques such as [[cyclic voltammetry]] to direct observations of interfacial processes.

===Geochemistry===
Geological phenomena such as [[Iron cycle|iron cycling]] and [[soil contamination]] are controlled by the interfaces between [[minerals]] and their environment. The atomic-scale structure and chemical properties of mineral–solution interfaces are studied using ''in situ'' [[Synchrotron light source|synchrotron]] X-ray techniques such as [[X-ray reflectivity]], [[X-ray standing waves]], and [[X-ray absorption spectroscopy]] as well as scanning probe microscopy. For example, studies of [[Toxic heavy metal|heavy metal]] or [[actinide]] adsorption onto mineral surfaces reveal molecular-scale details of adsorption, enabling more accurate predictions of how these contaminants travel through soils<ref>{{Cite journal |doi = 10.1016/j.gca.2008.02.013|bibcode = 2008GeCoA..72.1986C|title = Simultaneous inner- and outer-sphere arsenate adsorption on corundum and hematite|year = 2008|last1 = Catalano|first1 = Jeffrey G.|last2 = Park|first2 = Changyong|last3 = Fenter|first3 = Paul|last4 = Zhang|first4 = Zhan|journal = Geochimica et Cosmochimica Acta|volume = 72|issue = 8|pages = 1986–2004}}</ref> or disrupt natural dissolution–precipitation cycles.<ref>{{Cite journal |doi = 10.1016/j.gca.2013.11.036|title = Kinetics and mechanisms of cadmium carbonate heteroepitaxial growth at the calcite surface|year = 2014|last1 = Xu|first1 = Man|last2 = Kovarik|first2 = Libor|last3 = Arey|first3 = Bruce W.|last4 = Felmy|first4 = Andrew R.|last5 = Rosso|first5 = Kevin M.|last6 = Kerisit|first6 = Sebastien|journal = Geochimica et Cosmochimica Acta|volume = 134|pages = 221–233|url = https://zenodo.org/record/1258985|doi-access = free}}</ref>

==Physics{{anchor|Surface physics}}==
Surface physics can be roughly defined as the study of physical interactions that occur at interfaces.  It overlaps with surface chemistry. Some of the topics investigated in surface physics include [[friction]], [[surface states]], [[surface diffusion]], [[surface reconstruction]], surface [[phonons]] and [[plasmons]], [[epitaxy]], the emission and [[Quantum tunneling|tunneling]] of electrons, [[spintronics]], and the self-assembly of [[nanostructure]]s on surfaces. Techniques to investigate processes at surfaces include [[surface X-ray scattering]], [[scanning probe microscopy]], [[surface-enhanced Raman spectroscopy]] and [[X-ray photoelectron spectroscopy]].

==Analysis techniques==
The study and analysis of surfaces involves both physical and chemical analysis techniques.

Several modern methods probe the topmost 1–10&nbsp;nm of [[Interface (matter)|surface]]s exposed to vacuum.  These include [[angle-resolved photoemission spectroscopy]] (ARPES), [[X-ray photoelectron spectroscopy]] (XPS), [[Auger electron spectroscopy]] (AES), [[low-energy electron diffraction]] (LEED), [[electron energy loss spectroscopy]] (EELS), [[thermal desorption spectroscopy]] (TPD), [[ion scattering spectroscopy]] (ISS), [[secondary ion mass spectrometry]], [[dual-polarization interferometry]], and other surface analysis methods included in the [[list of materials analysis methods]]. Many of these techniques require vacuum as they rely on the detection of electrons or ions emitted from the surface under study. Moreover, in general [[ultra-high vacuum]], in the range of 10<sup>−7</sup> [[pascal (unit)|pascal]] pressure or better, it is necessary to reduce surface contamination by residual gas, by reducing the number of molecules reaching the sample over a given time period. At 0.1 mPa (10<sup>−6</sup> torr) partial pressure of a contaminant and [[Standard temperature and pressure|standard temperature]], it only takes on the order of 1 second to cover a surface with a one-to-one monolayer of contaminant to surface atoms, so much lower pressures are needed for measurements. This is found by an order of magnitude estimate for the (number) [[specific surface area]] of materials and the impingement rate formula from the [[kinetic theory of gases]].

Purely optical techniques can be used to study interfaces under a wide variety of conditions.  Reflection-absorption infrared, dual polarisation interferometry, [[surface-enhanced Raman spectroscopy]] and [[sum frequency generation spectroscopy]] can be used to probe solid–vacuum as well as solid–gas, solid–liquid, and liquid–gas surfaces. [[Multi-parametric surface plasmon resonance]] works in solid–gas, solid–liquid, liquid–gas surfaces and can detect even sub-nanometer layers.<ref>{{cite journal|last1=Jussila|first1=Henri|last2=Yang|first2=He|last3=Granqvist|first3=Niko|last4=Sun|first4=Zhipei|title=Surface plasmon resonance for characterization of large-area atomic-layer graphene film|journal=Optica|date=5 February 2016|volume=3|issue=2|pages=151|doi=10.1364/OPTICA.3.000151|bibcode=2016Optic...3..151J|doi-access=free}}</ref> It probes the interaction kinetics as well as dynamic structural changes such as liposome collapse<ref>{{cite journal|last1=Granqvist|first1=Niko|last2=Yliperttula|first2=Marjo|last3=Välimäki|first3=Salla|last4=Pulkkinen|first4=Petri|last5=Tenhu|first5=Heikki|last6=Viitala|first6=Tapani|title=Control of the Morphology of Lipid Layers by Substrate Surface Chemistry|journal=Langmuir|date=18 March 2014|volume=30|issue=10|pages=2799–2809|doi=10.1021/la4046622|pmid=24564782}}</ref> or swelling of layers in different pH. Dual-polarization interferometry is used to quantify the order and disruption in birefringent thin films.<ref>
{{cite journal
 |last1=Mashaghi |first1=A
 |last2=Swann |first2=M
 |last3=Popplewell |first3=J
 |last4=Textor |first4=M
 |last5=Reimhult |first5=E
 |date=2008
 |title=Optical Anisotropy of Supported Lipid Structures Probed by Waveguide Spectroscopy and Its Application to Study of Supported Lipid Bilayer Formation Kinetics
 |journal=[[Analytical Chemistry (journal)|Analytical Chemistry]]
 |volume=80 |issue=10 |pages=3666–76
 |doi=10.1021/ac800027s
 |pmid=18422336
}}</ref> This has been used, for example, to study the formation of lipid bilayers and their interaction with membrane proteins.

Acoustic techniques, such as [[quartz crystal microbalance with dissipation monitoring]], is used for time-resolved measurements of solid–vacuum, solid–gas and solid–liquid interfaces. The method allows for analysis of molecule–surface interactions as well as structural changes and viscoelastic properties of the adlayer.  

X-ray scattering and spectroscopy techniques are also used to characterize surfaces and interfaces. While some of these measurements can be performed using [[X-ray tube|laboratory X-ray sources]], many require the high intensity and energy tunability of [[synchrotron radiation]]. [[X-ray crystal truncation rod]]s (CTR) and [[X-ray standing waves|X-ray standing wave]] (XSW) measurements probe changes in surface and [[Adsorption|adsorbate]] structures with sub-Ångström resolution. [[Surface-extended X-ray absorption fine structure]] (SEXAFS) measurements reveal the coordination structure and chemical state of adsorbates. [[Grazing-incidence small-angle scattering|Grazing-incidence small angle X-ray scattering]] (GISAXS) yields the size, shape, and orientation of [[nanoparticles]] on surfaces.<ref>{{Cite journal | doi=10.1016/j.surfrep.2009.07.002| bibcode=2009SurSR..64..255R| title=Probing surface and interface morphology with Grazing Incidence Small Angle X-Ray Scattering| year=2009| last1=Renaud| first1=Gilles| last2=Lazzari| first2=Rémi| last3=Leroy| first3=Frédéric| journal=Surface Science Reports| volume=64| issue=8| pages=255–380}}</ref> The [[crystal structure]] and [[Texture (crystalline)|texture]] of thin films can be investigated using [[Grazing incidence diffraction|grazing-incidence X-ray diffraction]] (GIXD, GIXRD).

[[X-ray photoelectron spectroscopy]] (XPS) is a standard tool for measuring the chemical states of surface species and for detecting the presence of surface contamination. Surface sensitivity is achieved by detecting [[photoelectrons]] with kinetic energies of about 10–1000 [[Electronvolt|eV]], which have corresponding [[inelastic mean free path]]s of only a few nanometers. This technique has been extended to operate at near-ambient pressures (ambient pressure XPS, AP-XPS) to probe more realistic gas–solid and liquid–solid interfaces.<ref>{{Cite journal |doi = 10.1557/mrs2007.211|title = In Situ X-Ray Photoelectron Spectroscopy Studies of Gas-Solid Interfaces at Near-Ambient Conditions|year = 2007|last1 = Bluhm|first1 = Hendrik|last2 = Hävecker|first2 = Michael|last3 = Knop-Gericke|first3 = Axel|last4 = Kiskinova|first4 = Maya|last5 = Schlögl|first5 = Robert|last6 = Salmeron|first6 = Miquel|journal = MRS Bulletin|volume = 32|issue = 12|pages = 1022–1030| s2cid=55577979 |url = https://digital.library.unt.edu/ark:/67531/metadc900709/}}</ref> Performing XPS with hard X-rays at synchrotron light sources yields photoelectrons with kinetic energies of several keV (hard X-ray photoelectron spectroscopy, HAXPES), enabling access to chemical information from buried interfaces.<ref>{{Cite journal |doi = 10.1103/PhysRevLett.102.176805|pmid = 19518810|arxiv = 0809.1917|bibcode = 2009PhRvL.102q6805S|title = Profiling the Interface Electron Gas ofLaAlO3/SrTiO3Heterostructures with Hard X-Ray Photoelectron Spectroscopy|year = 2009|last1 = Sing|first1 = M.|last2 = Berner|first2 = G.|last3 = Goß|first3 = K.|last4 = Müller|first4 = A.|last5 = Ruff|first5 = A.|last6 = Wetscherek|first6 = A.|last7 = Thiel|first7 = S.|last8 = Mannhart|first8 = J.|last9 = Pauli|first9 = S. A.|last10 = Schneider|first10 = C. W.|last11 = Willmott|first11 = P. R.|last12 = Gorgoi|first12 = M.|last13 = Schäfers|first13 = F.|last14 = Claessen|first14 = R.|journal = Physical Review Letters|volume = 102|issue = 17|pages = 176805|s2cid = 43739895}}</ref>

Modern physical analysis methods include [[scanning tunneling microscope|scanning-tunneling microscopy]] (STM) and a family of methods descended from it, including [[atomic force microscopy]] (AFM). These microscopies have considerably increased the ability of surface scientists to measure the physical structure of many  surfaces. For example, they make it possible to follow reactions at the solid–gas interface in real space, if those proceed on a time scale accessible by the instrument.<ref>{{cite journal | last1 = Wintterlin | first1 = J. | last2 = Völkening | first2 = S. | last3 = Janssens | first3 = T. V. W. | last4 = Zambelli | first4 = T. | last5 = Ertl | first5 = G. | date = 1997 | title = Atomic and Macroscopic Reaction Rates of a Surface-Catalyzed Reaction | journal = [[Science (journal)|Science]] | volume = 278 | issue = 5345 | pages = 1931–4 | doi = 10.1126/science.278.5345.1931 |bibcode = 1997Sci...278.1931W | pmid=9395392}}</ref><ref>{{cite journal | last1 = Waldmann | first1 = T. | display-authors = etal   | date = 2012 | title = Oxidation of an Organic Adlayer: A Bird's Eye View | journal = [[Journal of the American Chemical Society]] | volume = 134 | issue = 21 | pages = 8817–8822 | doi = 10.1021/ja302593v | pmid=22571820}}</ref>

==See also==
{{Colbegin}}
*{{annotated link|Interface (matter)}}
*{{annotated link|Kelvin probe force microscope}}
*{{annotated link|Micromeritics}}
*{{annotated link|Surface modification of biomaterials with proteins}}
*{{annotated link|Surface finishing}}
*{{annotated link|Surface modification}}
*{{annotated link|Surface phenomenon}}
*{{annotated link|Tribology}}
{{colend}}

==References==
{{Reflist}}

==Further reading==
* {{cite book |last=Kolasinski |first=Kurt W. |date= 2012-04-30|title=Surface Science: Foundations of Catalysis and Nanoscience |edition=3 |url=https://www.wiley.com/en-us/Surface+Science%3A+Foundations+of+Catalysis+and+Nanoscience%2C+3rd+Edition-p-9781119990369 |publisher=Wiley |isbn=978-1119990352 }}
* {{cite book |last1=Attard |first1=Gary |last2=Barnes |first2=Colin |date= January 1998|title=Surfaces |url=https://global.oup.com/academic/product/surfaces-9780198556862?cc=no&lang=en& |publisher=Oxford Chemistry Primers |isbn=978-0198556862 }}

==External links==
{{commons category|Surface science}}
*[http://www.vega.org.uk/video/programme/24 "Ram Rao Materials and Surface Science"], a video from the Vega Science Trust
*[http://www.surfchem.net Surface Chemistry Discoveries]
*[https://guide.digitalsurf.com/en/guide.html Surface Metrology Guide]

{{Solid objects}}
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[[Category:Surface science| ]]
[[Category:Physical chemistry]]