|
Greninger Chart
In crystallography, a Greninger chartIt is named after Alden Buchanan Greninger (17 September 1907, Glendale, Oregon20 April 1998). is a chart that allows angular relations between zones and planes in a crystal to be directly read from an x-ray diffraction photograph. The Greninger chart is a simple trigonometric tool to determine ''g'' and ''d'' for a fixed sample-to-film distance. (If one uses a 2-d detector the problem of determining ''g'' and ''d'' could be solved mathematically using the equations which generate the Greninger chart) A new chart must be generated for different sample to detector distances. (2''s'' is 2''q'' for the diffraction peak and tan ''m'' is ''x''/''y'' for the Cartesian coordinates of the diffraction peak.) The Greninger chart gives directly the two angles needed to plot poles on the Wulff net. It is critical to keep track of the relative arrangement of the sample to the film, if photographic film is used then this is achieved by cutting the cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystallography
Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids. Crystallography is a fundamental subject in the fields of materials science and solid-state physics (condensed matter physics). The word "crystallography" is derived from the Greek word κρύσταλλος (''krystallos'') "clear ice, rock-crystal", with its meaning extending to all solids with some degree of transparency, and γράφειν (''graphein'') "to write". In July 2012, the United Nations recognised the importance of the science of crystallography by proclaiming that 2014 would be the International Year of Crystallography. denote a direction vector (in real space). * Coordinates in ''angle brackets'' or ''chevrons'' such as <100> denote a ''family'' of directions which are related by symmetry operations. In the cubic crystal system for example, would mean 00 10 01/nowiki> or the negative of any of those directions. * Miller indices in ''parentheses ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glendale, Oregon
Glendale is a city in Douglas County, Oregon, United States. The population was 874 at the 2010 census. History After construction of a railroad line south from Roseburg in 1881–83, Solomon Abraham, the local right-of-way agent, platted the community and named it "Julia" after his wife. After a dispute with Abraham, A. F. Morris, the chief engineer for the railroad, changed the name to "Glendale". A Julia post office was established in February 1883, and its name was changed to Glendale in August of the same year. L. D. Montgomery was the first postmaster. Fire destroyed much of Glendale's business district in 1928. Glendale was quickly rebuilt. In the 1880s, Russian-Jewish immigrants came here trying to escape the anti-Semitic rule of Alexander III. New Odessa, the first Jewish Communitarian Community in America settled near Glendale. By 1888 the New Odessa Community disbanded due to political and religious division. Glendale was incorporated in 1901. Geography Accord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chart
A chart (sometimes known as a graph) is a graphical representation for data visualization, in which "the data is represented by symbols, such as bars in a bar chart, lines in a line chart, or slices in a pie chart". A chart can represent tabular numeric data, functions or some kinds of quality structure and provides different info. The term "chart" as a graphical representation of data has multiple meanings: * A data chart is a type of diagram or graph, that organizes and represents a set of numerical or qualitative data. * Maps that are adorned with extra information (map surround) for a specific purpose are often known as charts, such as a nautical chart or aeronautical chart, typically spread over several map sheets. * Other domain-specific constructs are sometimes called charts, such as the chord chart in music notation or a record chart for album popularity. Charts are often used to ease understanding of large quantities of data and the relationships between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macroscopic single crystals are usually identifiable by their geometrical shape, consisting of flat faces with specific, characteristic orientations. The scientific study of crystals and crystal formation is known as crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification. The word ''crystal'' derives from the Ancient Greek word (), meaning both " ice" and " rock crystal", from (), "icy cold, frost". Examples of large crystals include snowflakes, diamonds, and table salt. Most inorganic solids are not crystals but polycrystals, i.e. many microscopic crystals fused together into a single solid. Polycrystals include most metals, rocks, ceramics, and ice. A third ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Diffraction
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information. Since many materials can form crystals—such as salts, metals, minerals, semiconductors, as well as various inorganic, organic, and biological molecules—X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences among vari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wulff Net
In mathematics, a stereographic projection is a perspective projection of the sphere, through a specific point on the sphere (the ''pole'' or ''center of projection''), onto a plane (the ''projection plane'') perpendicular to the diameter through the point. It is a smooth, bijective function from the entire sphere except the center of projection to the entire plane. It maps circles on the sphere to circles or lines on the plane, and is conformal, meaning that it preserves angles at which curves meet and thus locally approximately preserves shapes. It is neither isometric (distance preserving) nor equiareal (area preserving). The stereographic projection gives a way to represent a sphere by a plane. The metric induced by the inverse stereographic projection from the plane to the sphere defines a geodesic distance between points in the plane equal to the spherical distance between the spherical points they represent. A two-dimensional coordinate system on the stereogra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instant Film
Instant film is a type of photographic film that was introduced by Polaroid Corporation to produce a visible image within minutes or seconds of the photograph's exposure. The film contains the chemicals needed for developing and fixing the photograph, and the camera exposes and initiates the developing process after a photo has been taken. In earlier Polaroid instant cameras the film is pulled through rollers, breaking open a pod containing a reagent that is spread between the exposed negative and receiving positive sheet. This film sandwich develops for some time after which the positive sheet is peeled away from the negative to reveal the developed photo. In 1972, Polaroid introduced ''integral film'', which incorporated timing and receiving layers to automatically develop and fix the photo without any intervention from the photographer. Instant film has been available in sizes from (similar to 135 film) up to size, with the most popular film sizes for consumer snapshots b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bernal Chart
A Bernal chart (bər′nal ′chärt) in crystallography, is a chart used for indexing X-ray diffraction photographs from single crystals. From such a chart may be read the axial and radial cylindrical coordinates of that point in reciprocal space which corresponds to any particular X-ray reflection. When a single crystal is examined in an X-ray diffractometer such that the diffraction intensity is measured cylindrically around the crystal, it is convenient to use cylindrical coordinates to define the reciprocal lattice vectors and their terminal points. Different order reflections will be coaxial with the axis of rotation. These reflections are recorded as spots which lie on parallel lines known as layer lines. A reciprocal lattice vector can be represented by two mutually perpendicular vectors \zeta (along the rotation axis) and \xi in the horizontal plane (the plane perpendicular to the rotation axis) containing the X-ray beam. The third parameter specifying the reciprocal lattic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigonometry
Trigonometry () is a branch of mathematics that studies relationships between side lengths and angles of triangles. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies. The Greeks focused on the calculation of chords, while mathematicians in India created the earliest-known tables of values for trigonometric ratios (also called trigonometric functions) such as sine. Throughout history, trigonometry has been applied in areas such as geodesy, surveying, celestial mechanics, and navigation. Trigonometry is known for its many identities. These trigonometric identities are commonly used for rewriting trigonometrical expressions with the aim to simplify an expression, to find a more useful form of an expression, or to solve an equation. History Sumerian astronomers studied angle measure, using a division of circles into 360 degrees. They, and later the Babylonians, studied the ratios of the sid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-rays
X-rays (or rarely, ''X-radiation'') are a form of high-energy electromagnetic radiation. In many languages, it is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it in 1895 and named it ''X-radiation'' to signify an unknown type of radiation.Novelline, Robert (1997). ''Squire's Fundamentals of Radiology''. Harvard University Press. 5th edition. . X-ray wavelengths are shorter than those of ultraviolet rays and longer than those of gamma rays. There is no universally accepted, strict definition of the bounds of the X-ray band. Roughly, X-rays have a wavelength ranging from 10 nanometers to 10 picometers, corresponding to frequencies in the range of 30 petahertz to 30 exahertz ( to ) and photon energies in the range of 100 eV to 100 keV, respectively. X-rays can penetrate many solid substances such as construction materials and living tissue, so X-ray radiography is widely used in medic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
