Editing Surface science (section)

==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>