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Topic: Physisorption

	EPFL Lecture #2 (Venables) (Site not responding. Last check: 2007-10-20)
		A qualitative distinction is usually made between chemisorption and physisorption, in terms of the relative binding strengths and mechanisms.
		Physisorption is weaker, and is often described as implying that no chemical interaction is present.
		A better distinction is that in physisorption, the energy of interaction is largely due to the van der Waals force.
	venables.asu.edu /grad/EPFL2.html (2165 words)

	Gas adsorption - porosity measurements
		Thus physisorption experiments for surface characterization are performed at very low temperature, usually at liquid nitrogen or liquid argon boiling temperature at atmospheric pressure and provide porosity information.
		Gas physisorption is considered non-selective, thus filling the surface step by step (or layer by layer) depending on the available solid surface and the relative pressure.
		Filling the first layer enables the measurement of the surface area of the material because the amount of gas adsorbed when the mono-layer is saturated is proportional to the entire surface, that includes the internal and external surface.
	www.porosity-measurement.com /gasadsorption.html (2059 words)

	Syllabi 2004-2005 B-KUL-I0504A Adsorption
		The physisorption of permanent gases at low temperatures is a common method to characterize the texture of highly divided solid materials.
		Physisorption at surfaces results from a combination of attraction and repulsion forces, determining the adsorption energy.
		Nitrogen physisorption at 77 K is currently used to determine the specific surface area of an adsorbent and to characterize the micro- and mesopores (BET method, t-plot analysis, capillary condensation, Kelvin equation).
	www.kuleuven.ac.be /onderwijs/aanbod2004/syllabi/I0504AE.htm (486 words)

	PHYSISORPTION (Site not responding. Last check: 2007-10-20)
		Die Physisorption ist eine spezielle Form der Adsorption, bei der im Unterschied zur Chemisorption das Adsorbatmolekül durch physikalische Kräfte an das Substrat gebunden wird.
		Eigenschaften der Physisorption sind die vollständige Reversibilität und die Möglichkeit, multimolekulare Adsorbatschichten zu bilden.
		Eine weitere Anwendung der Physisorption ist die Luft- oder Wasserreinigung mit Hilfe von Aktivkohlefiltern.
	www.toonorama.com /encyclopedia/P/Physisorption (204 words)

	Gravimetric Sorption Analysis - Technology Introduction (Site not responding. Last check: 2007-10-20)
		The sorption of gases and vapors on solid material samples can either be a physical (physisorption), or a chemical (chemisorption) process.
		Physisorption is a temperature and pressure dependent process and is most commonly recorded as isotherm data (using a constant temperature bath).
		Gravimetric sorption analyzers are ideally suited to both gas and liquid sorption, but are really well suited for vapor sorption, and in particular, the sorption of water vapor (often termed moisture sorption).
	www.xonics.com /Technology/Gravimetry.html (242 words)

	Kids.net.au - Encyclopedia Surface chemistry - (Site not responding. Last check: 2007-10-20)
		Surface chemistry is chemical phenomena that occur at the interface of two phases, usually between a gas and a solid or between a liquid and a solid.
		One important aspect of surface chemistry studies is to determine whether a molecule attaches itself to a surface by chemisorption or by physisorption.
		Surface chemistry is of particular importance to the field of heterogeneous catalysis.
	www.kids.net.au /encyclopedia-wiki/su/Surface_chemistry (141 words)

	paint adhesion mechanisms
		Adsorption: "Chemical" bonding effects ranging from strong chemical bonds (chemisorption) across the bond interface to weaker van der Waals forces* (physisorption) that are based on temporary of permanent dipole interactions.
		Physisorption: physical adsorption - by intermolecular forces (van der Waals forces) which do not involve a significant change in the electron orbital patterns.
		It has been noted that a sharp distinction between chemisorption and physisorption is not always possible, as is the case for chemical and physical interactions in general.
	www.corrosion-club.com /paintadhesion.htm (374 words)

	Physisorption (Site not responding. Last check: 2007-10-20)
		Adsorption is divided into the two sub-categories of physical adsorption (physisorption) or van der Waals adsorption and chemical adsorption (chemisorption) and the adsorption process can be determined whether chemical bonds are formed during the process.
		Physisorption is applicable to all adsorbate-adsorbent systems provided the conditions of pressure and temperature are suitable whereas chemisorption may only occur if the system is capable of making a chemical bond.
		Physisorption occurs to varying extents for all adsorbates, gases and vapours, with all adsorbing solids and the effect increases with decreasing temperature or increasing pressure.
	www.staff.ncl.ac.uk /a.j.fletcher/physisorption.htm (3540 words)

	2
		For large molecules that are still capable of physisorption at high surface temperatures where available free energy is sufficient to overcome the barrier, this precursor-mediated pathway may be highly effective.
		The measured energies are proportional to such molecular properties as the polarizability and the bulk enthalpy of vaporization of the adsorbate indicating that dispersion forces are primarily responsible for the physisorption well depth.
		For physisorption, the attractive interaction between the adsorbate and the substrate is due to van der Waals forces.
	www.princeton.edu /~gscoles/theses/sean/chapter3.html (3877 words)

	AdsorbedSurf.html (Site not responding. Last check: 2007-10-20)
		Physisorption: adsorption with no chemical reaction (meaning no charge transfer has occurred), just a va der Waals force due to dipole moments.
		Physisorption is technically important in operation sorption and cryo pumps.
		Physisorption and van der Waals forces are very important factors in such processes.
	www.zaiko.kyushu-u.ac.jp /~watanabe/SemiconSS/Adsorption/AdsorbedSurf.html (1946 words)

	Gas Adsorption
		In physisorption (physical adsorption), there is a weak van der Waals attraction of the adsorbate to the surface.
		During the process of physisorption, the chemical identity of the adsorbate remains intact, i.e.
		This interaction is much stronger than physisorption, and, in general, chemisorption has more stringent requirements for the compatibility of adsorbate and surface site than physisorption.
	itl.chem.ufl.edu /4411L_f00/ads/ads_1.html (3049 words)

	Text of MIJ-NSR Volume 1, Article 31
		Using this assumption, we develop a quasi-thermodynamic approach which allows the trends in nitride MBE to be modeled, along with the prediction of the growth conditions where extra liquid phase appears on the surface.
		The physisorption precursor can be represented schematically (Figure 1) as a potential well separated from the crystal surface.
		It is seen that the consideration of the physisorption precursor drastically shifts the position and shape of the calculated boundary of the liquid phase formation.
	nsr.mij.mrs.org /1/31/text.html (1623 words)

	United States Patent Application: 0040038408
		The method of claim 86, wherein a recognition moiety is attached to said organic layer by an interaction which is a member selected from the group consisting of covalent bonding, ionic bonding, chemisorption, physisorption, and combinations thereof.
		In further preferred embodiments, the recognition moiety is attached to the organic layer by an interaction which is a member selected from the group consisting of covalent bonding, ionic bonding, chemisorption, physisorption, and combinations thereof.
		In further embodiments, the recognition moiety is attached to the surface by an interaction which is a member selected from the group consisting of covalent bonding, ionic bonding, chemisorption, physisorption, and combinations thereof.
	appft1.uspto.gov /netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=/netahtml/PTO/srchnum.html&r=1&f=G&l=50&s1='20040038408' (17781 words)

	HELIUM ATOM REFLECTIVITY STUDY OF PHYSISORPTION AND CHEMISORPTION ON SINGLE CRYSTAL METAL SURFACES
		Twenty-five hydrocarbons (alkanes, alkenes, and related cyclic molecules) were measured and found to be only capable of physisorption on Au(111) with an adsorption energy which is proportional to bulk properties of the molecule such as heat of vaporization or polarizability.
		Although the physisorption energy of the 1-alkanethiols increases linearly as a function of chain length, the activation energy for desorption from the chemisorbed state is constant at 124 kJ/mol.
		Physisorption and Chemisorption of Alkanethiols and Alkylsulfides on Au(111)
	www.princeton.edu /~gscoles/theses/sean/start.html (572 words)

	LANGMUIR-ADSORPTION
		With physical adsorption (physisorption) there is only an increase in surface concentration during adsorption.
		Not only the heat of adsorption but also the the activation energy of the adsorption process is higher with chemisorption than with physisorption.
		As a consequence physisorption is prelavent at lower temperatures and chemisorption at higher temperatures.
	www.thuisexperimenteren.nl /infopages/langmuir/langmuir.htm (630 words)

	2.4 PE Curves & Energetics of Adsorption
		There is no barrier to prevent the atom or molecule which is approaching the surface from entering this physisorption well, i.e.
		In reality, of course, such a mechanism for dissociative hydrogen chemisorption is not practical - the energy downpayment associated with breaking the H-H bond is far too severe.
		The characteristics of this type of dissociative adsorption process are clearly going to be strongly influenced by the position of the crossing point of the two curves (molecular physisorption v's dissociative chemisorption) - relatively small shifts in the position of either of the two curves can significantly alter the size of any barrier to chemisorption.
	www.chem.qmw.ac.uk /surfaces/scc/scat2_4.htm (1143 words)

	Jahrbuch-CD der MPG 2003 - Physisorption of molecular oxyg (Site not responding. Last check: 2007-10-20)
		Physisorption of molecular oxygen on single-wall carbon nanotube bundles and graphite
		We present a study on the kinetics of oxygen adsorption and desorption from single-wall carbon nanotube (SWNT) and highly oriented pyrolytic graphite (HOPG) samples.
		In combination with molecular mechanics calculations we show that the observed binding energies for both systems can be attributed to van der Waals interactions, i.e., physisorption.
	www.mpg.de /forschungsergebnisse/wissVeroeffentlichungen/archivListenJahrbuch/2002/01/publZIM134.html (151 words)

	Learn more about Physisorption in the online encyclopedia. (Site not responding. Last check: 2007-10-20)
		Learn more about Physisorption in the online encyclopedia.
		Hint: Play with putting spaces before and after your words to see the different results you get.
		Physisorption is a process whereby a molecule adheres to a surface without the formation of a chemical bond, usually by van der Waals forces or electrostatic attraction.
	www.onlineencyclopedia.org /p/ph/physisorption.html (117 words)

	Chemisorption -- Die Chemisorption ist eine spezielle Form der Adsorption, b... (Site not responding. Last check: 2007-10-20)
		Die Chemisorption ist eine spezielle Form der Adsorption, bei der im Unterschied zur Physisorption das Adsorbatmolekül durch stärkere chemische Bindungen an das Substrat gebunden wird.
		Meistens ist die Physisorption eine Vorstufe zur Chemisorption.
		Die Chemisorption ist im Unterschied zur Physisorption nicht immer reversibel und erfordert eine hohe Aktivierungsenergie.
	chemisorption.exsudo.de (184 words)

	High Resolution Studies of Interfacial Polymer Physisorption and its Mediation by Surfactant - Suppl
		This application note describes the use of DPI for quantitative analysis in real time of the physisorption of an amphophilic polymer and a non-ionic surfactant at the solid—liquid interface, and the mediating effect exerted by the surfactant on the polymer sorption process.
		Quantitative layer values after sample physisorption for 10 minutes followed by a 10-minute rinse (except for ‘surfactant during rinse’ which was taken after 1 minute).
		Crucially, the structural information obtained for the polymer physisorption process highlights the mechanistic effect of the presence of the surfactant.
	www.azonano.com /details.asp?ArticleID=1261 (1470 words)

	Thermo Electron Corporation --Sorptomatic 1990 (Site not responding. Last check: 2007-10-20)
		Physisorption measurements to determine the specific surface area and mesopore size distribution in porous materials by using inert gases such as nitrogen, argon, carbon dioxide, etc.
		In case of non-porous materials kripton is commonly used as measuring gas, the physisorption isotherm shows a maximun pressure of approx.
		It is therefore necessary to enable the Sorptomatic 1990 to collect equilibrium pressures in a very low and restricted pressure range.
	www.thermo.com /eThermo/CDA/Products/Product_Detail/1,1075,12967-113,00.html (328 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		Far more interesting than physisorption, at least from a practical point of view, is the case where we have a real chemical bond between the surface and an atom or a molecule.
		The scenario is similar to chemical bonding between atoms and the whole complex of surface and adsorbate may be viewed as one giant molecule.
		Different scenarios are possible (a) molecular chemisorption (b) molecular physisorption and (c) dissociative chemisorption.
	www.ifa.au.dk /~philip/ea04/surflec/node30.html (1441 words)

	Materials Research Lab - "I. Physisorption of hydroxide ions from aqueous solution to a hydrophobic surface"; II. ... (Site not responding. Last check: 2007-10-20)
		Materials Research Lab - "I. Physisorption of hydroxide ions from aqueous solution to a hydrophobic surface"; II.
		Experimental studies indicate that the interface between water and a hydrophobic medium is negatively charged.
		We argue that this collective motion is generated by superpositions of instantaneous normal mode vibrations along diffusive paths.
	www.mrl.ucsb.edu /mrl/events/seminars/show_seminar.php?key=1087509600Zangi (334 words)

	ASAP 2010-Switching Between Chemisorption and Physisorption - PSS
		With this level of functionality, switching from a chemisorption analysis to a physisorption analysis requires the removal of trace gases from the analyzer itself.
		After evacuation, the instrument is ready for physisorption analysis.
		When the outgassing rate is less than 5 microns per minute, the instrument is ready for physisorption analysis.
	www.pss.aus.net /products/micromeritics/tech_docs/technical_notes/t1.html (184 words)

	Physisorption Of Hydrogen On Carbon Substrate - aquarium-tips.com (Site not responding. Last check: 2007-10-20)
		Physisorption Of Hydrogen On Carbon Substrate - aquarium-tips.com
		Read about physisorption of hydrogen on carbon substrate in the free online encyclopedia and dictionary.
		Find results for physisorption of hydrogen on carbon substrate and anything else you are looking for instantly!
	www.aquarium-tips.com /Physisorption-Of-Hydrogen-On-Carbon-Substrate.htm (586 words)

	[No title] (Site not responding. Last check: 2007-10-20)
		Molecular beam translational spectroscopy of physisorption bound states of molecules on metal surfaces.
		The present results for HD-Cu(111) and HD-Au(111) are analyzed by comparison with a close coupling calculation to provide potential well parameters.
		The method has been used to study the surface temperature dependence of one of the resonances down to 40 K and provides insight into a possible elementary step in physisorption.
	www.ruhr-uni-bochum.de /pc1/deutsch/pub/6.htm (126 words)

	Surface Nanostructures: Quantitative Characterisation by Dual Polarisation Interferometry (DPI) - Su
		Measuring the Physisorption of Polyethyleneimine (PEI) Polymer on Silicon Oxynitride Surfaces
		) polymer onto a silicon oxynitride surface and the subsequent physisorption of 80nm silica spheres to the surface.
		This is consistent with a surface coverage of 25.2% for the silica spheres.
	www.azonano.com /Details.asp?ArticleID=1258 (1290 words)

	MRS Bulletin: September 2002 (Site not responding. Last check: 2007-10-20)
		The interaction is based on van der Waals attractive forces (physisorption), or the overlap of the highest occupied molecular orbitals of carbon with the hydrogen electron, overcoming the activation-energy barrier for hydrogen dissociation (chemisorption).
		While the physisorption of hydrogen limits the hydrogen-to-carbon ratio to less than one hydrogen atom per two carbon atoms (i.e., 4.2 mass%), in chemisorption, a ratio of two hydrogen atoms per one carbon atom is realized (e.g., in polyethylene).
		Nanocrystalline or amorphous carbon exhibits an intermediate state for hydrogen between physisorption and chemisorption and absorbs up to one hydrogen atom per carbon atom.
	www.mrs.org /publications/bulletin/2002/sep/zuttel_abstract.html (201 words)

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