Jump to content

Surface science

From Wikipedia, the free encyclopedia
For the journal, seeSurface Science (journal).
STMimage of aquinacridoneadsorbate.Theself-assembledsupramolecularchains of theorganic semiconductorare adsorbed on agraphitesurface.

Surface scienceis the study ofphysicalandchemicalphenomena that occur at theinterfaceof twophases,includingsolid–liquidinterfaces, solid–gasinterfaces, solid–vacuuminterfaces, andliquid–gasinterfaces. It includes the fields ofsurface chemistryandsurface physics.[1]Some related practical applications are classed assurface engineering.The science encompasses concepts such asheterogeneous catalysis,semiconductor device fabrication,fuel cells,self-assembled monolayers,andadhesives.Surface science is closely related tointerface and colloid science.[2]Interfacial chemistry and physics are common subjects for both. The methods are different. In addition, interface and colloid science studiesmacroscopicphenomenathat occur inheterogeneoussystems due to peculiarities of interfaces.

History

[edit]

The field of surface chemistry started withheterogeneous catalysispioneered byPaul SabatieronhydrogenationandFritz Haberon theHaber process.[3]Irving Langmuirwas also one of the founders of this field, and the scientific journal on surface science,Langmuir,bears his name. TheLangmuir adsorption equationis 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 Ertlin 1974 described for the first time the adsorption ofhydrogenon apalladiumsurface using a novel technique calledLEED.[4]Similar studies withplatinum,[5]nickel,[6][7]andiron[8]followed. Most recent developments in surface sciences include the 2007Nobel prize of ChemistrywinnerGerhard Ertl's advancements in surface chemistry, specifically his investigation of the interaction between carbon monoxide molecules and platinum surfaces.

Chemistry

[edit]

Surface chemistry can be roughly defined as the study of chemical reactions at interfaces. It is closely related tosurface engineering,which aims at modifying the chemical composition of a surface by incorporation of selected elements orfunctional groupsthat produce various desired effects or improvements in the properties of the surface or interface. Surface science is of particular importance to the fields ofheterogeneous catalysis,electrochemistry,andgeochemistry.

Catalysis

[edit]

The adhesion of gas or liquid molecules to the surface is known asadsorption.This can be due to eitherchemisorptionorphysisorption,and the strength of molecular adsorption to a catalyst surface is critically important to the catalyst's performance (seeSabatier principle). However, it is difficult to study these phenomena in real catalyst particles, which have complex structures. Instead, well-definedsingle crystalsurfaces of catalytically active materials such asplatinumare 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.[9]

Relationships between the composition, structure, and chemical behavior of these surfaces are studied usingultra-high vacuumtechniques, including adsorption andtemperature-programmed desorptionof molecules,scanning tunneling microscopy,low energy electron diffraction,andAuger electron spectroscopy.Results can be fed into chemical models or used toward therational designof new catalysts. Reaction mechanisms can also be clarified due to the atomic-scale precision of surface science measurements.[10]

Electrochemistry

[edit]

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 theelectrical 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 usingspectroscopy, scanning probe microscopy[11]andsurface X-ray scattering.[12][13]These studies link traditional electrochemical techniques such ascyclic voltammetryto direct observations of interfacial processes.

Geochemistry

[edit]

Geologic phenomena such asiron cyclingandsoil contaminationare controlled by the interfaces betweenmineralsand their environment. The atomic-scale structure and chemical properties of mineral-solution interfaces are studied usingin situsynchrotronX-ray techniques such asX-ray reflectivity,X-ray standing waves,andX-ray absorption spectroscopyas well as scanning probe microscopy. For example, studies ofheavy metaloractinideadsorption onto mineral surfaces reveal molecular-scale details of adsorption, enabling more accurate predictions of how these contaminants travel through soils[14]or disrupt natural dissolution-precipitation cycles.[15]

Physics

[edit]

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 includefriction,surface states,surface diffusion,surface reconstruction,surfacephononsandplasmons,epitaxy,the emission andtunnelingof electrons,spintronics,and the self-assembly ofnanostructureson surfaces. Techniques to investigate processes at surfaces includesurface X-ray scattering,scanning probe microscopy,surface-enhanced Raman spectroscopyandX-ray photoelectron spectroscopy.

Analysis techniques

[edit]

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

Several modern methods probe the topmost 1–10 nm ofsurfacesexposed to vacuum. These includeangle-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 thelist 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 generalultra-high vacuum,in the range of 10−7pascalpressure 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 (10−6torr) partial pressure of a contaminant andstandard 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 areaof materials and the impingement rate formula from thekinetic 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 spectroscopyandsum frequency generation spectroscopycan be used to probe solid–vacuum as well as solid–gas, solid–liquid, and liquid–gas surfaces.Multi-parametric surface plasmon resonanceworks in solid–gas, solid–liquid, liquid–gas surfaces and can detect even sub-nanometer layers.[16]It probes the interaction kinetics as well as dynamic structural changes such as liposome collapse[17]or swelling of layers in different pH. Dual-polarization interferometry is used to quantify the order and disruption in birefringent thin films.[18]This has been used, for example, to study the formation of lipid bilayers and their interaction with membrane proteins.

Acoustic techniques, such asQuartz 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 usinglaboratory X-ray sources,many require the high intensity and energy tunability ofsynchrotron radiation.X-ray crystal truncation rods(CTR) andX-ray standing wave(XSW) measurements probe changes in surface andadsorbatestructures 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 X-ray scattering(GISAXS) yields the size, shape, and orientation ofnanoparticleson surfaces.[19]Thecrystal structureandtextureof thin films can be investigated usinggrazing-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 detectingphotoelectronswith kinetic energies of about 10-1000eV,which have correspondinginelastic mean free pathsof 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.[20]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.[21]

Modern physical analysis methods includescanning-tunneling microscopy(STM) and a family of methods descended from it, includingatomic force microscopy(AFM). These microscopies have considerably increased the ability and desire 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.[22][23]

See also

[edit]

References

[edit]
  1. ^Prutton, Martin (1994).Introduction to Surface Physics.Oxford University Press.ISBN978-0-19-853476-1.
  2. ^Luklema, J. (1995–2005).Fundamentals of Interface and Colloid Science.Vol. 1–5. Academic Press.
  3. ^Wennerström, Håkan; Lidin, Sven."Scientific Background on the Nobel Prize in Chemistry 2007 Chemical Processes on Solid Surfaces"(PDF).
  4. ^Conrad, H.;Ertl, G.;Latta, E.E. (February 1974). "Adsorption of hydrogen on palladium single crystal surfaces".Surface Science.41(2): 435–446.Bibcode:1974SurSc..41..435C.doi:10.1016/0039-6028(74)90060-0.
  5. ^Christmann, K.;Ertl, G.;Pignet, T. (February 1976). "Adsorption of hydrogen on a Pt(111) surface".Surface Science.54(2): 365–392.Bibcode:1976SurSc..54..365C.doi:10.1016/0039-6028(76)90232-6.
  6. ^Christmann, K.; Schober, O.;Ertl, G.;Neumann, M. (June 1, 1974). "Adsorption of hydrogen on nickel single crystal surfaces".The Journal of Chemical Physics.60(11): 4528–4540.Bibcode:1974JChPh..60.4528C.doi:10.1063/1.1680935.
  7. ^Christmann, K.; Behm, R. J.;Ertl, G.;Van Hove, M. A.; Weinberg, W. H. (May 1, 1979). "Chemisorption geometry of hydrogen on Ni(111): Order and disorder".The Journal of Chemical Physics.70(9): 4168–4184.Bibcode:1979JChPh..70.4168C.doi:10.1063/1.438041.
  8. ^Imbihl, R.; Behm, R. J.; Christmann, K.;Ertl, G.;Matsushima, T. (May 2, 1982). "Phase transitions of a two-dimensional chemisorbed system: H on Fe(110)".Surface Science.117(1): 257–266.Bibcode:1982SurSc.117..257I.doi:10.1016/0039-6028(82)90506-4.
  9. ^Fischer-Wolfarth, Jan-Henrik; Farmer, Jason A.; Flores-Camacho, J. Manuel; Genest, Alexander; Yudanov, Ilya V.; Rösch, Notker; Campbell, Charles T.; Schauermann, Swetlana; Freund, Hans-Joachim (2010). "Particle-size dependent heats of adsorption of CO on supported Pd nanoparticles as measured with a single-crystal microcalorimeter".Physical Review B.81(24): 241416.Bibcode:2010PhRvB..81x1416F.doi:10.1103/PhysRevB.81.241416.hdl:11858/00-001M-0000-0011-29F8-F.
  10. ^Lewandowski, M.; Groot, I.M.N.; Shaikhutdinov, S.; Freund, H.-J. (2012). "Scanning tunneling microscopy evidence for the Mars-van Krevelen type mechanism of low temperature CO oxidation on an FeO(111) film on Pt(111)".Catalysis Today.181:52–55.doi:10.1016/j.cattod.2011.08.033.hdl:11858/00-001M-0000-0010-50F9-9.
  11. ^Gewirth, Andrew A.; Niece, Brian K. (1997). "Electrochemical Applications ofin SituScanningProbe Microscopy ".Chemical Reviews.97(4): 1129–1162.doi:10.1021/cr960067y.PMID11851445.
  12. ^Nagy, Zoltán; You, Hoydoo (2002)."Applications of surface X-ray scattering to electrochemistry problems".Electrochimica Acta.47(19): 3037–3055.doi:10.1016/S0013-4686(02)00223-2.
  13. ^Gründer, Yvonne; Lucas, Christopher A. (2016-11-01)."Surface X-ray diffraction studies of single crystal electrocatalysts".Nano Energy.29:378–393.doi:10.1016/j.nanoen.2016.05.043.ISSN2211-2855.
  14. ^Catalano, Jeffrey G.; Park, Changyong; Fenter, Paul; Zhang, Zhan (2008). "Simultaneous inner- and outer-sphere arsenate adsorption on corundum and hematite".Geochimica et Cosmochimica Acta.72(8): 1986–2004.Bibcode:2008GeCoA..72.1986C.doi:10.1016/j.gca.2008.02.013.
  15. ^Xu, Man; Kovarik, Libor; Arey, Bruce W.; Felmy, Andrew R.; Rosso, Kevin M.; Kerisit, Sebastien (2014)."Kinetics and mechanisms of cadmium carbonate heteroepitaxial growth at the calcite surface".Geochimica et Cosmochimica Acta.134:221–233.doi:10.1016/j.gca.2013.11.036.
  16. ^Jussila, Henri; Yang, He; Granqvist, Niko; Sun, Zhipei (5 February 2016)."Surface plasmon resonance for characterization of large-area atomic-layer graphene film".Optica.3(2): 151.Bibcode:2016Optic...3..151J.doi:10.1364/OPTICA.3.000151.
  17. ^Granqvist, Niko; Yliperttula, Marjo; Välimäki, Salla; Pulkkinen, Petri; Tenhu, Heikki; Viitala, Tapani (18 March 2014). "Control of the Morphology of Lipid Layers by Substrate Surface Chemistry".Langmuir.30(10): 2799–2809.doi:10.1021/la4046622.PMID24564782.
  18. ^ Mashaghi, A; Swann, M; Popplewell, J; Textor, M; Reimhult, E (2008). "Optical Anisotropy of Supported Lipid Structures Probed by Waveguide Spectroscopy and Its Application to Study of Supported Lipid Bilayer Formation Kinetics".Analytical Chemistry.80(10): 3666–76.doi:10.1021/ac800027s.PMID18422336.
  19. ^Renaud, Gilles; Lazzari, Rémi; Leroy, Frédéric (2009). "Probing surface and interface morphology with Grazing Incidence Small Angle X-Ray Scattering".Surface Science Reports.64(8): 255–380.Bibcode:2009SurSR..64..255R.doi:10.1016/j.surfrep.2009.07.002.
  20. ^Bluhm, Hendrik; Hävecker, Michael; Knop-Gericke, Axel; Kiskinova, Maya; Schlögl, Robert; Salmeron, Miquel (2007)."In Situ X-Ray Photoelectron Spectroscopy Studies of Gas-Solid Interfaces at Near-Ambient Conditions".MRS Bulletin.32(12): 1022–1030.doi:10.1557/mrs2007.211.S2CID55577979.
  21. ^Sing, M.; Berner, G.; Goß, K.; Müller, A.; Ruff, A.; Wetscherek, A.; Thiel, S.; Mannhart, J.; Pauli, S. A.; Schneider, C. W.; Willmott, P. R.; Gorgoi, M.; Schäfers, F.; Claessen, R. (2009). "Profiling the Interface Electron Gas ofLaAlO3/SrTiO3Heterostructures with Hard X-Ray Photoelectron Spectroscopy".Physical Review Letters.102(17): 176805.arXiv:0809.1917.Bibcode:2009PhRvL.102q6805S.doi:10.1103/PhysRevLett.102.176805.PMID19518810.S2CID43739895.
  22. ^Wintterlin, J.; Völkening, S.; Janssens, T. V. W.; Zambelli, T.; Ertl, G. (1997). "Atomic and Macroscopic Reaction Rates of a Surface-Catalyzed Reaction".Science.278(5345): 1931–4.Bibcode:1997Sci...278.1931W.doi:10.1126/science.278.5345.1931.PMID9395392.
  23. ^Waldmann, T.; et al. (2012). "Oxidation of an Organic Adlayer: A Bird's Eye View".Journal of the American Chemical Society.134(21): 8817–8822.doi:10.1021/ja302593v.PMID22571820.

Further reading

[edit]
[edit]
Wikimedia Commons has media related toSurface science.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Surface_science&oldid=1217094085"