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Reflectance spectroscopy
Reflectance spectroscopy, also called IR reflectance spectroscopy, measures light reflected from a material's surface as a function of wavelength, yielding film thickness, roughness, and optical constants for applications from thin-film metrology to remote sensing.
Reflected Brownian motion
Reflected Brownian motion, also called regulated Brownian motion, is a Markov process behaving like Brownian motion in a domain but pushed back at its boundary.
Reflecting telescope
A reflecting telescope, or reflector, uses a curved mirror instead of a lens to focus light; Isaac Newton built the first successful one in 1668.
Reflection (physics)
Reflection is the change in direction of a wavefront at an interface so that part or all of the wave returns into the medium it came from.
Reflection coefficient
The reflection coefficient, also called the coefficient of reflection, is the fraction of a wave's amplitude reflected at a boundary, used in transmission lines, acoustics, and optics.
Reflection equation algebra
A reflection equation algebra is a quadratic associative algebra built from matrix solutions of the reflection equation, which describes particle scattering from a boundary in integrable systems.
Reflection high-energy electron diffraction
Reflection high-energy electron diffraction (RHEED) is a surface analysis technique in which grazing-angle high-energy electrons reveal the top atomic layers, used to monitor epitaxial thin-film growth in molecular beam epitaxy.
Reflection interference contrast microscopy
Reflection interference contrast microscopy (RICM), or interference reflection microscopy, is a label-free optical technique measuring nanometer-scale distances between a cell membrane and a transparent surface, widely used to study cell adhesion.
Reflection nebula
A reflection nebula is a cloud of interstellar gas and dust that produces no light of its own but scatters starlight from nearby stars, usually appearing blue.
Reflection principle
A reflection principle in set theory states that any first-order statement true of the universe of sets V is already true in some smaller set-sized Vα.
Reflection principles
A reflection principle is a formal schema asserting that a theory is sound, meaning every sentence it proves is true; it extends theories beyond what they can prove about themselves.
Reflection seismology
Reflection seismology, also called seismic reflection, is a geophysical method that maps subsurface rock layers from reflected seismic waves and is the petroleum industry's principal imaging tool.
Reflection spectroscopy
Reflection spectroscopy measures the light returned by a material's surface to determine its composition, structure, and optical constants across the ultraviolet, visible, near-infrared, and mid-infrared ranges.
Reflection symmetry
Reflection symmetry, also called line symmetry or reflective symmetry, is the invariance of an object or pattern under reflection across a fixed line or plane of symmetry.
Reflectionless metasurfaces
Reflectionless metasurfaces are electrically thin engineered surfaces that transform electromagnetic waves, such as by refraction or focusing, while producing no specular reflection of their own.
Reflections on the Motive Power of Fire
Reflections on the Motive Power of Fire (Réflexions sur la puissance motrice du feu) is an 1824 scientific treatise by French engineer Sadi Carnot, regarded as the founding document of thermodynamics.
Reflectometry
Reflectometry is a measurement technique that directs light, X-rays, or neutrons at a surface and analyzes reflected intensity to determine film thickness, refractive index, and interface quality.
Reflector sight
A reflector sight, also called a reflex sight, is an optical sight that projects an illuminated aiming point onto glass, patented by Howard Grubb in 1901.
Reflectron
A reflectron, also called an ion mirror, is a component of a time-of-flight mass spectrometer that improves mass resolution by compensating for ions' energy spread.
Reflexive operator algebra
A reflexive operator algebra is an algebra of bounded operators equal to the algebra of all operators sharing its invariant subspaces, a notion tied to the invariant subspace problem.
Reflexive relation
A reflexive relation, also called the reflexive property, is a binary relation on a set in which every element is related to itself, as with the identity relation.
Reflexive space
A reflexive space is a Banach space that coincides with its second dual under the canonical embedding, so that its closed unit ball is weakly compact.
Reflexive thematic analysis
Reflexive thematic analysis is a qualitative method in which researchers treat their subjectivity as an analytic resource, actively generating themes of shared meaning across a dataset.
Reflux
Reflux, also called heating under reflux, is a laboratory technique that holds a chemical reaction at the solvent's boiling point by condensing vapor back into the flask.
Reformate
Reformate, also called reformed gasoline, is the high-octane liquid hydrocarbon product of catalytic reforming of naphtha, used as a gasoline blendstock, the main source of xylenes, and a refinery hydrogen source.
Reformatsky reaction
The Reformatsky reaction is an organic reaction in which an α-halo ester reacts with an aldehyde or ketone in the presence of zinc to form a β-hydroxy ester.
Reforming (chemistry)
Reforming is a family of catalytic processes that converts naphtha into high-octane gasoline blendstock and methane into synthesis gas and hydrogen, supplying about 47% of global hydrogen.
Refracting telescope
A refracting telescope, or refractor, is an optical telescope that collects and focuses light with a front objective lens. It was the first type of telescope, made from 1608.
Refraction
Refraction is the change in direction of a wave, including light, sound, and water waves, when it crosses a boundary into a medium where its speed differs, following Snell's law.
Refraction of light in water
Refraction of light in water is the bending of light rays crossing the air–water interface, making a straight oar look bent and a pool bottom look closer.