علم السطوح

STM image of a quinacridone adsorbate. The self-assembled supramolecular chains of the organic semiconductor are adsorbed on a graphite surface.

علم السطوح Surface science، هو دراسة الظاهرة الفيزيائية والكيميائية التي تحدث على السطح البيني لطورين، بما في ذلك سطوح صلب-سائل أو صلب-غاز أو سائل-غاز. لذا فهو يتضمن: فيزياء السطوح وكيمياء السطوح.[1] بعض التطبيقات العملية تصنف على أنها من ضمن هندسة السطوح. يتضمن هذا العلم دراسة مواضيع من ضمنها التحفيز اللامتجانس heterogeneous catalysis، تصنيع الوسائل نصف الناقلة semiconductor device fabrication ، خلايا الوقود fuel cell، الطبقات الأحادية ذاتية التجمع self-assembled monolayer والالتصاق adhesive. علوم السطوح وثيقة الصلة بعلوم الغرويدات والسطوح البينية Interface and Colloid Science[2]. فكيمياء وفيزياء السطوح البينية مشتركة بين الاثنتين لكن بوسائل بحث مختلفة. بالإضافة لذلك تدرس علوم الغرويدات والسطوح البينية الظاهرة الجهرية أو الماكروية التي تحدث في النظمة اللامتجانسة نتيجة للتجمعات السطحية.


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التاريخ

الكيمياء

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 groups 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.

التحفيز

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.[3]

Relationships between the composition, structure, and chemical behavior of these surfaces are studied using ultra-high vacuum techniques, including adsorption and 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.[4]

الكيمياء الكهربية

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 spectroscopy, scanning probe microscopy[5] and surface X-ray scattering.[6][7] These studies link traditional electrochemical techniques such as cyclic voltammetry to direct observations of interfacial processes.

كيمياء الأرض

Geologic phenomena such as 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 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 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[8] or disrupt natural dissolution-precipitation cycles.[9]

فيزياء السطوح

تقنيات التحليل

انظر أيضاً

المصادر

  1. ^ Prutton, Martin (1994). Introduction to Surface Physics. Oxford University Press. ISBN 0-19-853476-0.
  2. ^ Lyklema. J. Fundamentals of Interface and Colloid Science, Academic Press, vol.1-5 (1995-2005)
  3. ^ 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.
  4. ^ 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.
  5. ^ Gewirth, Andrew A.; Niece, Brian K. (1997). "Electrochemical Applications ofin Situ Scanning Probe Microscopy". Chemical Reviews. 97 (4): 1129–1162. doi:10.1021/cr960067y. PMID 11851445.
  6. ^ 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.
  7. ^ Gründer, Yvonne; Lucas, Christopher A. (2016-11-01). "Surface X-ray diffraction studies of single crystal electrocatalysts". Nano Energy (in الإنجليزية). 29: 378–393. doi:10.1016/j.nanoen.2016.05.043. ISSN 2211-2855.
  8. ^ 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.
  9. ^ 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.

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