|
Du Noüy Ring Method
In surface science, the du Noüy ring method is a technique for measuring the surface tension of a liquid. The method involves slowly lifting a ring, often made of platinum, from the surface of a liquid. The force, , required to raise the ring from the liquid's surface is measured and related to the liquid's surface tension, : :F= w_\text + 2\pi \cdot (r_i + r_a) \cdot \gamma where is the radius of the inner ring of the liquid film pulled and is the radius of the outer ring of the liquid film. is the weight of the ring minus the buoyant force due to the part of the ring below the liquid surface. When the ring's thickness is much smaller than its diameter, this equation can be simplified to: :F= w_\text + 4\pi R \gamma where is the average of the inner and outer radius of the ring, i.e. \tfrac. This technique was proposed by the French physicist Pierre Lecomte du Noüy (1883–1947) in a paper published in 1925. The measurement is performed with a force tensiometer, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Science
Surface science is the study of physical and chemical phenomena that occur at the interface of two 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''. Some related practical applications are classed as surface engineering. The science encompasses concepts such as heterogeneous catalysis, semiconductor device fabrication, fuel cells, self-assembled monolayers, and adhesives. Surface science is closely related to interface and colloid science. 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 on hydrogenation and Fritz Haber on the Haber process. Irving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Tension
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to float on a water surface without becoming even partly submerged. At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). There are two primary mechanisms in play. One is an inward force on the surface molecules causing the liquid to contract. Second is a tangential force parallel to the surface of the liquid. This ''tangential'' force is generally referred to as the surface tension. The net effect is the liquid behaves as if its surface were covered with a stretched elastic membrane. But this analogy must not be taken too far as the tension in an elastic membrane is dependent on the amount of deformation of the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, and plasma), and is the only state with a definite volume but no fixed shape. A liquid is made up of tiny vibrating particles of matter, such as atoms, held together by intermolecular bonds. Like a gas, a liquid is able to flow and take the shape of a container. Most liquids resist compression, although others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly constant density. A distinctive property of the liquid state is surface tension, leading to wetting phenomena. Water is by far the most common liquid on Earth. The density of a liquid is usually close to that of a solid, and much higher than that of a gas. Therefore, liquid and solid are both termed condensed matte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pierre Lecomte Du Noüy
Pierre Lecomte du Noüy (; 20 December 1883, Paris – 22 September 1947, New York City) was a French biophysicist and philosopher. He is probably best remembered by scientists for his work on the surface tension, and other properties, of liquids. Life and work Du Noüy was a descendant of the French dramatist Pierre Corneille. His mother wrote many novels, one of which, ''Amitié Amoureuse'', was translated into 16 languages and ran for 600 editions in France. Born and educated in France, du Noüy obtained the degrees of LL.B., Ph.B., Sc.B., Ph.D., and Sc.D. He was an associate member of the Rockefeller Institute working in Alexis Carrel's lab from 1920 through 1928, head for 10 years of the biophysics division of the Pasteur Institute, and the author of some 200 published papers. He invented the Tensiometer, a scientific apparatus that used his du Noüy ring method to measure the surface tension of liquids. Du Noüy believed that mankind should have confidence in sci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tensiometer (surface Tension)
In surface science, a tensiometer is a measuring instrument used to measure the surface tension () of liquids or surfaces. Tensiometers are used in research and development laboratories to determine the surface tension of liquids like coatings, lacquers or adhesives. A further application field of tensiometers is the monitoring of industrial production processes like parts cleaning or electroplating. Types Goniometer/Tensiometer Surface scientists commonly use an optical goniometer/tensiometer to measure the surface tension and interfacial tension of a liquid using the pendant or sessile drop methods. A drop is produced and captured using a CCD camera. The drop profile is subsequently extracted, and sophisticated software routines then fit the theoretical Young-Laplace equation to the experimental drop profile. The surface tension can then be calculated from the fitted parameters. Unlike other methods, this technique requires only a small amount of liquid making it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weighing Scale
A scale or balance is a device used to measure weight or mass. These are also known as mass scales, weight scales, mass balances, and weight balances. The traditional scale consists of two plates or bowls suspended at equal distances from a fulcrum. One plate holds an object of unknown mass (or weight), while known masses are added to the other plate until static equilibrium is achieved and the plates level off, which happens when the masses on the two plates are equal. The perfect scale rests at neutral. A spring scale will make use of a spring of known stiffness to determine mass (or weight). Suspending a certain mass will extend the spring by a certain amount depending on the spring's stiffness (or spring constant). The heavier the object, the more the spring stretches, as described in Hooke's law. Other types of scales making use of different physical principles also exist. Some scales can be calibrated to read in units of force (weight) such as newtons instead of unit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dyne
The dyne (symbol: dyn; ) is a derived unit of force specified in the centimetre–gram–second (CGS) system of units, a predecessor of the modern SI. History The name dyne was first proposed as a CGS unit of force in 1873 by a Committee of the British Association for the Advancement of Science. Definition The dyne is defined as "the force required to accelerate a mass of one gram at a rate of one centimetre per second squared". An equivalent definition of the dyne is "that force which, acting for one second, will produce a change of velocity of one centimetre per second in a mass of one gram". One dyne is equal to 10 micronewtons, 10−5 N or to 10 nsn (nano sthenes) in the old metre–tonne–second system of units. : 1 dyn = 1 g⋅cm/s2 = 10−5 kg⋅m/s2 = 10−5 N : 1 N = 1 kg⋅m/s2 = 105 g⋅cm/s2 = 105 dyn Use The dyne per centimetre is a unit traditionally used to measure surface tension. For example, the surface tension of distilled water is 71.99 dyn/c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sessile Drop Technique
image:Contact angle.svg, 400px, Fig 1: An illustration of the sessile drop technique with a liquid droplet partially wetting a solid substrate. is the contact angle, and represent the solid–gas, gas–liquid, and liquid–solid interfaces, respectively. In materials science, the sessile drop technique is a method used for the characterization of solid surface energy, surface energies, and in some cases, aspects of liquid surface energies. The main premise of the method is that by placing a droplet of liquid with a known surface energy and contact angle, the surface energy of the solid substrate can be calculated. The liquid used for such experiments is referred to as the probe liquid, and the use of several different probe liquids is required. Probe liquid The surface energy is measured in units of Joules per area, which is equivalent in the case of liquids to surface tension, measured in Newtons per meter. The overall surface tension/energy of a liquid can be acquired th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilhelmy Plate
A Wilhelmy plate is a thin plate that is used to measure equilibrium surface or interfacial tension at an air–liquid or liquid–liquid interface. In this method, the plate is oriented perpendicular to the interface, and the force exerted on it is measured. Based on the work of Ludwig Wilhelmy, this method finds wide use in the preparation and monitoring of Langmuir films. Detailed description The Wilhelmy plate consists of a thin plate usually on the order of a few square centimeters in area. The plate is often made from filter paper, glass or platinum which may be roughened to ensure complete wetting. In fact, the results of the experiment do not depend on the material used, as long as the material is wetted by the liquid. The plate is cleaned thoroughly and attached to a balance with a thin metal wire. The force on the plate due to wetting is measured using a tensiometer or microbalance and used to calculate the surface tension (\gamma) using the Wilhelmy equation: :\ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
