Diffraction is a phenomenon that occurs when a wave encounters an obstacle or a slit that is comparable in size to its wavelength. It results in the bending and spreading of waves as they pass around the edges of the obstacle or through the slit. This behavior is observed with various types of waves, including sound waves, light waves, and water waves.
Diffraction gratings are optical devices used to separate light into its constituent wavelengths or colors. They consist of a surface that has a large number of closely spaced lines or grooves, which can be either reflective or transmissive. When light encounters the grating, it interacts with these structures, leading to constructive and destructive interference effects based on the wavelength of the light.
Small-angle scattering (SAS) is a powerful experimental technique used to study the structure of materials at the nanoscale. It is commonly applied in fields such as chemistry, biology, materials science, and condensed matter physics. The technique involves the scattering of X-rays, neutrons, or light (e.g., using small-angle X-ray scattering, or SAXS; small-angle neutron scattering, or SANS; and small-angle light scattering, or SALS) off of a sample.
X-ray scattering is a powerful analytical technique used to study the structural properties of materials at the atomic or molecular level. This method involves directing X-rays at a sample and analyzing the way these rays scatter off the material. The scattering of X-rays can provide valuable information about the arrangement of atoms, molecular structures, phase transitions, and other properties of the sample.
Addressed Fiber Bragg Structures refer to a type of optical fiber device that incorporates Fiber Bragg Gratings (FBGs). A Fiber Bragg Grating is a periodic variation in the refractive index of optical fiber, which reflects specific wavelengths of light while transmitting others. These structures are widely used for various applications, including sensing, telecommunications, and signal processing.
The Airy disk is a pattern of light observed when a point source of light, such as a distant star, is imaged through a circular aperture, such as a lens or an optical telescope. It occurs due to the diffraction of light, which causes waves to spread out when passing through the aperture. The Airy disk is characterized by a central bright spot, known as the Airy central maximum, surrounded by a series of concentric dark and bright rings.
The Arago spot, also known as the Poinsot spot, is a phenomenon observed in the diffraction pattern of light when it passes through a circular aperture or around a circular obstacle. It is named after the French physicist François Arago, who studied this effect in the early 19th century. When light waves encounter a circular obstacle, they bend around it and create a diffraction pattern.
Atmospheric diffraction is the bending of light waves as they pass through different layers of the atmosphere with varying temperatures and densities. This phenomenon occurs due to the interaction of light with atmospheric particles and the varying refractive index of air caused by changes in temperature, pressure, and humidity. When light waves encounter obstacles or pass through apertures, they can bend around the edges, leading to effects such as the spreading of light and the formation of patterns.
Babinet's principle is a concept in wave optics that relates to the diffraction of waves, particularly light, when they encounter an obstacle or aperture. It states that the diffraction pattern created by a particular aperture is identical to the diffraction pattern produced by an obstacle of the same shape and size but with its area blocked instead of open.
Bragg's law is a fundamental principle in the field of crystallography and X-ray diffraction. It relates the angles at which X-rays are diffracted by a crystalline material to the spacing between its atomic planes. The law is named after William Lawrence Bragg and his father, William Henry Bragg, who formulated it in 1913.
Coherent Diffraction Imaging (CDI) is a powerful imaging technique used primarily in the fields of materials science, biology, and nanotechnology. It allows researchers to obtain high-resolution images of the internal structures of samples without the need for lenses, which can often introduce aberrations or restrict resolution.
Convergent Beam Electron Diffraction (CBED) is a technique used in electron microscopy, particularly in the field of crystallography and materials science, to study the crystallographic structure of materials at the atomic level. It is an extension of conventional electron diffraction methods and allows for the collection of detailed information about the symmetry and electronic structure of crystals. In CBED, a focused beam of electrons is converged onto the sample, typically using a high-resolution transmission electron microscope (HRTEM).
Dark-field X-ray microscopy is an advanced imaging technique that exploits X-ray scattering to visualize small structures or features in samples, particularly biological specimens and materials at the nanoscale. This method is distinct from traditional X-ray imaging, which typically relies on transmitted X-rays to create images. ### Key Features of Dark-field X-ray Microscopy: 1. **Scattering Detection**: In dark-field configurations, the microscope is designed to detect scattered X-rays rather than those that pass straight through the sample.
A diffraction-limited system refers to an optical system that is limited in resolution by the diffraction of light rather than by other factors such as optical aberrations or imperfections in the optical components. In such systems, the smallest details that can be resolved are determined by the wavelength of light being used and the numerical aperture of the optical system.
Diffraction efficiency refers to the effectiveness with which a diffraction grating or similar optical component disperses incoming light into its various diffraction orders. It is typically defined as the ratio of the power of the desired diffracted beam to the power of the incident beam, usually expressed as a percentage.
Diffraction refers to the bending and spreading of waves when they encounter an obstacle or an aperture that is comparable in size to the wavelength of the waves. When discussing diffraction from slits, we typically refer to the phenomenon that occurs when light (or other waves) passes through one or more narrow slits. ### Key Concepts: 1. **Single-Slit Diffraction**: - When light passes through a single narrow slit, it spreads out rather than traveling in straight lines.
A diffraction grating is an optical component with a periodic structure that diffracts light into several beams. The grating consists of multiple closely spaced slits or grooves, which can be either reflective or transmissive. When light waves encounter the grating, they are scattered at specific angles according to the principles of wave interference, producing a spectrum of colors.
Diffraction in time typically refers to the phenomenon where waves spread out and bend around obstacles or through openings, but instead of focusing on spatial dimensions, it considers how these waves behave over time.
A diffraction spike is an optical phenomenon commonly observed in photographs of bright light sources, especially stars, taken with telescopes or camera lenses that utilize a diaphragm with sharp edges. When light from these sources enters the lens system, it is diffracted—meaning it bends around the edges of the aperture (the opening through which light passes). The result of this diffraction can create streaks or spikes radiating outward from the bright light source in the image.
A diffractive beam splitter is an optical device that uses diffraction principles to split an incoming beam of light into multiple output beams. Unlike traditional beam splitters, which typically rely on reflection and transmission through a partially reflective surface, diffractive beam splitters use specially designed micro-patterns etched or printed on a surface to manipulate the phase front of the incoming light wave.
An Echelle grating is a type of diffraction grating used in spectroscopy to disperse light into its component wavelengths. It is characterized by having a large number of closely spaced grooves (or lines) that are typically arranged at an angle to maximize the diffraction efficiency. The key features of an Echelle grating include: 1. **High Dispersion**: Echelle gratings are designed to produce a high degree of angular dispersion due to their shallow groove angle and high groove density.
Electron diffraction is a technique used to study the structural properties of materials at the atomic or molecular level by utilizing the wave-like behavior of electrons. When a beam of electrons interacts with a material, it can be scattered by the atoms in the material, producing a diffraction pattern. This phenomenon is based on the principles of wave-particle duality, which describes how particles like electrons can exhibit properties of both particles and waves.
Energy-dispersive X-ray diffraction (EDXD) is a technique that combines aspects of both X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). It is primarily used to analyze the structural properties of materials at the atomic or molecular level. The method involves measuring the intensity of X-rays diffracted by a material as a function of their energy, providing information on both the crystalline structure and elemental composition of the sample.
Ewald's sphere is a geometric construct used in crystallography to visualize the relationship between the reciprocal lattice of a crystal and the diffraction of X-rays, neutrons, or electrons. It helps in understanding the conditions under which a crystal will diffract incident radiation and plays a crucial role in the interpretation of scattering experiments.
Fiber Bragg Grating (FBG) is a specific type of optical device that is used primarily in fiber optic communication and sensing applications. An FBG consists of a periodic variation in the refractive index of the optical fiber core, which is created through various techniques such as exposure to UV light. This periodic change in refractive index acts as a wavelength-selective reflector.
The Flack parameter, often denoted as \( f \), is a term used in crystallography to describe the absolute configuration of a chiral molecule. It is particularly relevant when analyzing the results of X-ray crystallography experiments, where the precise arrangement of atoms in a crystal is determined. The Flack parameter provides information about the enantiomeric composition of the crystal structure.
Fraunhofer diffraction refers to a type of diffraction pattern produced when light waves pass through a slit or around an obstacle and are observed at a considerable distance from the aperture or obstacle, where the incoming and outgoing waves can be treated as parallel. This condition is typically satisfied when the source of light and the observation screen are placed at infinity or sufficiently far away compared to the size of the aperture.
Fraunhofer diffraction describes the diffraction patterns observed when light passes through a small aperture or around an obstacle, and it is analyzed at a far distance from the aperture or object. Under these conditions, the incoming wavefront can be approximated as planar waves. The mathematical formulation of the Fraunhofer diffraction pattern can be expressed in terms of the Fourier transform of the aperture function.
The Fraunhofer distance is a concept used in optics, particularly in the study of wave propagation and diffraction patterns. It refers to the distance from a wave source at which the wavefronts can be considered parallel, and thus the far-field approximation can be applied. This approximation simplifies the mathematical treatment of the wave behavior, especially when analyzing diffraction patterns.
Fresnel diffraction is a type of wave diffraction that occurs when a wavefront encounters an obstacle or aperture with dimensions comparable to its wavelength. It is named after the French engineer and physicist Augustin-Jean Fresnel, who developed the theory to better understand the behavior of light.
The Fresnel number is a dimensionless quantity used in optics to characterize the diffraction of light through an aperture or around obstacles. It is named after the French engineer and physicist Augustin-Jean Fresnel, who made significant contributions to the understanding of wave optics.
A Fresnel zone is a concept used in wave propagation, particularly in the context of radio, microwave, and optical communications. It is related to the diffraction of waves as they travel through space and helps in understanding how obstacles can affect signal strength and clarity. In a more formal sense, the Fresnel zone is defined as a series of concentric ellipsoidal regions surrounding the straight line path between a transmitter and a receiver.
Gas electron diffraction (GED) is a technique used to study the molecular structure of gas-phase samples by examining the scattering of electrons as they pass through a gas. It can be particularly useful for obtaining information about small molecules, radicals, and other transient species that may not have a stable crystalline form or that would be difficult to study using traditional X-ray crystallography.
A Greninger chart, also known as a Greninger diagram, is a type of graphical representation used primarily in the fields of engineering and project management. It helps in visualizing the relationship between different elements of a project, such as tasks, resources, and timelines. The chart typically focuses on the allocation of resources over time, allowing for better understanding and management of project dynamics.
A grism is an optical component used in spectroscopes and other imaging devices to disperse light into its constituent wavelengths. It combines the functions of a grating and a prism: it consists of a transparent optical element, typically made of glass, that has a diffraction grating etched onto one of its surfaces. The grism operates by diffracting light into different wavelengths, allowing for spectroscopic analysis.
The Hybrid Input-Output (HIO) algorithm is a computational approach often used in the context of optimization problems, particularly in the field of signal processing, image reconstruction, and iterative algorithms for phase retrieval. While the term "Hybrid Input-Output" may be used in various contexts, it is frequently associated with methods that combine different iterative techniques (input-output algorithms) to achieve improved convergence properties or performance in solving specific problems.
InXitu is a company that specializes in the development of advanced analytical instruments for the aerospace and defense industries, as well as for other scientific applications. The company focuses on providing real-time data solutions through innovative technology, particularly in the area of materials analysis and characterization. InXitu's instruments are designed for use in diverse environments, including on-site analyses, to support decision-making processes in critical applications.
The International Centre for Diffraction Data (ICDD) is a non-profit organization that serves the scientific community by providing a comprehensive database of diffraction data for crystalline materials. Founded in 1978, the ICDD focuses on the collection, organization, and dissemination of data related to X-ray, neutron, and electron diffraction. The ICDD is best known for its Powder Diffraction File (PDF), which is a critical resource for researchers in materials science, chemistry, mineralogy, and other fields.
The Kapitsa–Dirac effect is a quantum phenomenon that occurs when a beam of particles, such as electrons, interacts with a periodic potential in a way that results in the diffraction of the particles into discrete energy states. This effect was first predicted by physicists Peter Kapitsa and Paul Dirac in the 1930s.
Kikuchi lines are a phenomenon observed in electron diffraction patterns, particularly in materials science and crystallography when analyzing the structures of crystalline materials using techniques such as electron backscatter diffraction (EBSD) or transmission electron microscopy (TEM). They appear as bands or lines in the diffraction pattern and are an important feature for understanding the crystalline structure and orientation of the material being studied. These lines result from the inelastic scattering of electrons and the interaction of the electron beam with the periodic lattice structure of the crystal.
Kinematic diffraction is a concept in the field of X-ray diffraction and crystallography that describes the way X-rays scatter off a crystalline material. It is based on kinematic theory, which simplifies the treatment of diffraction by considering the contributions of each atom in the crystal independently, without accounting for multiple scattering events. In kinematic diffraction, the following key points apply: 1. **Single Scattering**: It assumes that each X-ray photon interacts with one atom and is scattered only once.
Kirchhoff's diffraction formula is a foundational concept in the field of wave optics, specifically addressing the behavior of waves as they propagate from a source and encounter obstacles. Established by the physicist Gustav Kirchhoff in the 19th century, the formula provides a mathematical framework for predicting how light waves will diffract around edges and through apertures.
The Kirchhoff integral theorem is a fundamental result in mathematical physics, particularly in the field of wave propagation and acoustics. It provides a way to express the values of a wave field (such as sound or electromagnetic waves) in terms of its values over a surface enclosing a volume. The theorem is particularly useful for solving problems involving wave equations.
A Laser Voltage Prober (LVP) is a specialized piece of equipment used in the field of semiconductor testing and characterization. It combines the principles of laser technology with electrical measurement techniques to provide high-precision voltage measurements on integrated circuits (ICs) and other electronic components. Here's how it generally works: 1. **Laser Technology**: The LVP uses a focused laser beam to illuminate specific areas of a semiconductor device.
Long-period fiber gratings (LPFGs) are specialized types of optical fiber devices that are used to selectively couple light between the guided modes of the fiber and radiative modes or cladding modes. These gratings are created by periodically refracting the core refractive index of optical fibers, typically through techniques like ultraviolet (UV) light exposure or by using electric field poling.
Low-energy electron diffraction (LEED) is a surface analysis technique used primarily to determine the surface structure of crystalline materials. In this method, low-energy electrons, typically in the range of 1 to 200 eV, are directed at the surface of a crystalline sample.
Momentum transfer refers to the process by which momentum is exchanged between two or more systems, typically involving interactions between particles or bodies. This exchange can occur in various physical contexts, such as collisions, fluid dynamics, and particle physics. In a collision between two objects, for example, momentum transfer occurs as the moving object exerts a force on the stationary object, resulting in a change in their velocities.
A multifocal diffractive lens is an optical device designed to provide multiple focal points, allowing it to focus light at different distances. This type of lens is mainly used in applications like eyeglasses, contact lenses, and intraocular lenses for cataract surgery. Here’s how it works: 1. **Diffractive Optics**: The lens incorporates microstructures on its surface that manipulate the light through diffraction.
Multipole density formalism is a theoretical framework used to describe the electronic distribution within molecules and materials by expanding the electron density in terms of multipole moments. This approach is particularly useful in quantum chemistry and condensed matter physics to analyze and visualize electronic structures. ### Key Features of Multipole Density Formalism: 1. **Electron Density Expansion**: The electron density \(\rho(\mathbf{r})\) of a system can be expanded in terms of a series of multipole moments.
Neutron diffraction is a technique used to investigate the atomic and magnetic structures of materials by scattering neutrons off of them. It is similar to X-ray diffraction, but it utilizes neutrons instead of X-rays. The key aspects of neutron diffraction include: 1. **Neutron Source**: Neutrons are produced in nuclear reactors or spallation sources. These neutrons are then directed toward the sample being studied.
New Worlds Mission is a NASA initiative aimed at searching for potentially habitable exoplanets and studying their atmospheres to potentially identify signs of life. One of the key components of this mission involves the use of a spacecraft equipped with advanced technology, including a coronagraph that can block out the light from a star and allow for direct imaging and analysis of its surrounding planets. The mission aims to characterize the environment of these planets and understand their atmospheres, composition, and potential habitability.
Powder diffraction is a scientific technique used to analyze the crystalline structure of materials in powder form. This method is commonly employed in fields such as materials science, chemistry, geology, and metallurgy to determine the arrangement of atoms within a crystalline solid. **Key features of powder diffraction include:** 1. **Sample Requirements**: The sample must be in powder form, which allows the random orientation of crystallites.
Precession Electron Diffraction (PED) is a technique used in electron microscopy to enhance the quality of diffraction data obtained from crystalline materials. It involves the precession of the electron beam around a predetermined axis while the electron diffraction pattern is recorded. Key features of Precession Electron Diffraction include: 1. **Beam Precession**: Instead of maintaining a static electron beam, the beam is rotated or precessed at a specific angle relative to the sample.
Reflection High-Energy Electron Diffraction (RHEED) is a surface-sensitive analytical technique used primarily to characterize the structure and properties of thin films and surfaces at the atomic level. The method involves directing a beam of high-energy electrons—typically in the range of 10 to 100 keV—at a shallow angle onto the surface of a sample, such as a thin film or a crystalline substrate.
In the context of structural biology and X-ray crystallography, "resolution" refers to the level of detail that can be discerned in the electron density map produced during protein or molecular structure determination. It is typically expressed in terms of the smallest distance between features that can be distinguished in the final structure, measured in angstroms (Å).
Rietveld refinement is a powerful mathematical technique used in crystallography to extract precise structural information from powder diffraction data. Named after Hugo Rietveld, who introduced the method in the 1960s, this approach is particularly effective for analyzing complex materials where single crystal diffraction is difficult or impossible. In powder diffraction, a sample is finely powdered, and X-ray or neutron diffraction patterns are collected.
STED microscopy, or Stimulated Emission Depletion microscopy, is a super-resolution imaging technique used in fluorescence microscopy. It was developed to overcome the diffraction limit of conventional light microscopy, which typically restricts resolution to about 200 nanometers for visible light. The fundamental principle behind STED microscopy involves the use of two laser beams: 1. **Excitation Beam**: This laser excites fluorescent molecules (fluorophores) in the sample, causing them to emit light.
Scattering amplitude is a fundamental concept in quantum mechanics and quantum field theory that describes the probability amplitude for a scattering process to occur. It quantifies how likely it is for incoming particles (or waves) to be scattered into a specific final state after interacting with each other. ### Key Points about Scattering Amplitude: 1. **Quantum Mechanics Framework**: In the context of quantum mechanics, the scattering amplitude is related to the wave function of the incoming and outgoing particles.
Schaefer–Bergmann diffraction refers to a specific phenomenon related to the diffraction of light or waves when they encounter a periodic structure. This term is often associated with studies in the field of optics or materials science, particularly in the context of understanding how waves interact with different types of materials or surface structures. In general, diffraction occurs when waves, such as light, encounter an obstacle or a slit that is comparable in size to their wavelength.
The Scherrer equation is a formula used in materials science and crystallography to estimate the size of crystalline domains in a material based on X-ray diffraction data. It provides a way to quantify the average size of coherently diffracting crystallites or grains within a sample. The equation is particularly useful for nanomaterials and thin films.
Selected Area Diffraction (SAD) is a technique used in transmission electron microscopy (TEM) to analyze the crystallographic structure of materials. It allows researchers to obtain diffraction patterns from a specific area of a sample rather than from the entire specimen. This technique is particularly useful for studying the local structural properties of crystalline materials, including defects, phase composition, and orientation.
Strain scanning is a technique used to measure and analyze the strain (deformation) experienced by materials when subjected to external forces or environmental changes. It is commonly applied in fields such as materials science, structural engineering, and geophysics to assess how materials or structures respond under stress.
In the context of condensed matter physics, a "superstructure" refers to a periodic arrangement of atoms or molecules that goes beyond the basic repeating unit of a crystal lattice. This term is commonly used to describe phenomena where the atomic arrangement exhibits a longer-range periodicity, often resulting from certain interactions within the material, such as those related to changes in composition, temperature, or pressure.
The Talbot effect, also known as the Talbot phenomenon, is an optical phenomenon that occurs when coherent light (such as from a laser) is illuminated on a periodic structure, such as a grating. When the light passes through the grating, it creates a series of diffraction patterns that repeat at specific distances, known as the Talbot distance.
Ultrafast X-ray refers to a category of X-ray imaging and spectroscopy techniques that utilize extremely short pulses of X-ray radiation, typically on the scale of femtoseconds (10^-15 seconds). These techniques are powerful tools for studying fast processes at the atomic and molecular levels in real time, such as chemical reactions, phase transitions, and electronic dynamics.
Ultrafast electron diffraction (UED) is a powerful experimental technique used to investigate dynamic processes in materials and molecular systems on very short timescales, typically in the femtosecond (10^-15 seconds) regime. It combines concepts from electron diffraction with ultrafast laser technology to capture real-time structural changes in materials as they undergo rapid transformations.
Ultrasonic grating is a technique that involves the use of ultrasonic waves to create a pattern or grating effect in a medium. This method can be applied in various fields, such as materials science, acoustics, and engineering, and can serve multiple purposes including diagnostics, imaging, and material characterization. In essence, ultrasonic grating works by generating high-frequency sound waves that can propagate through different materials.
The Uniform Theory of Diffraction (UTD) is a mathematical approach used in the fields of electromagnetic wave propagation and antenna theory. It is a refined method for analyzing how waves diffract around edges and over surfaces, particularly in situations where geometrical optics does not provide sufficient accuracy. ### Key Features of UTD: 1. **Physical Basis**: UTD combines principles of geometric optics with diffraction theory.
Wide-angle X-ray scattering (WAXS) is a technique used in material science and structural biology to investigate the atomic and molecular structure of materials. It involves the scattering of X-rays from a sample, providing information about the arrangement of atoms within that sample. ### Key Components of WAXS: 1. **X-Ray Source**: WAXS uses X-ray beams generated from synchrotrons or X-ray tubes to probe the sample.
X-ray crystallography is a widely used technique for determining the atomic and molecular structure of a crystalline substance. The technique involves directing X-ray beams at a crystal and analyzing the pattern of X-rays that are diffracted by the crystal lattice. Here's a basic overview of the process: 1. **Crystal Formation**: The first step in X-ray crystallography is the growth of high-quality crystals of the substance being studied. These crystals must be of sufficient size and purity to provide clear diffraction patterns.
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The term "zone axis" is commonly used in the context of crystallography and materials science, particularly in electron microscopy and diffraction studies. It refers to a specific direction in a crystal lattice that is used to analyze the orientation and symmetry of the crystal structure. In more detail: 1. **Crystallography**: In crystal structures, the zone axis is a line that represents the intersection of a series of lattice planes.
