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Raman spectroscopy
Raman spectroscopy, based on the Raman effect discovered by C.V. Raman in 1928, identifies a sample's chemical composition and molecular structure by measuring laser light scattered with shifted vibrational energies.
Raman thermometry
Raman thermometry is a contactless optical technique that measures local temperature from Raman peak shifts, with sub-micron resolution, used to characterize semiconductors and microelectronic devices.
Raman transition
A Raman transition is a two-photon process in which two laser beams differing by a qubit's energy splitting couple its levels through a virtual intermediate state.
Ramanan Krishnamoorti
Ramanan Krishnamoorti is a chemical engineer and polymer scientist at the University of Houston, known for work on polymer nanocomposites and a leader in energy innovation there.
Ramanath Cowsik
Ramanath Cowsik is an Indian-American astroparticle physicist, the James S. McDonnell Professor of Space Sciences at Washington University in St. Louis, elected to the National Academy of Sciences in 2004.
Ramanathan Vaidhyanathan
Ramanathan Vaidhyanathan is an Indian materials chemist at IISER Pune who studies metal-organic frameworks for carbon capture, known for a 2010 Science paper on CO2 binding.
Ramanujan summation
Ramanujan summation is a technique by Srinivasa Ramanujan for assigning finite values to divergent series, famously giving 1 + 2 + 3 + ⋯ the value −1/12.
Ramanujan tau function
The Ramanujan tau function is the sequence of Fourier coefficients of the weight-12 cusp form Δ, introduced by Ramanujan in 1916. It is multiplicative, satisfies striking congruences, and Deligne proved its size bound in 1974.
Ramanujan–Petersson conjecture
The Ramanujan–Petersson conjecture, also called the Ramanujan conjecture, bounds the Fourier coefficients of modular forms; Ramanujan proposed it in 1916 and Deligne proved it for holomorphic forms.
Ramanujan–Sato series
Ramanujan–Sato series are infinite series for 1/π extending the seventeen series Ramanujan announced in 1914, built from a construction associated with Takeshi Sato; the Chudnovsky series used for world-record π computations belongs to the family.
Ramanujan's congruences
Ramanujan's congruences are three divisibility properties of the partition function p(n), discovered by Srinivasa Ramanujan in 1919: p(5n+4), p(7n+5), and p(11n+6) are divisible by 5, 7, and 11.
Ramanujan's lost notebook
Ramanujan's lost notebook is a manuscript of over 600 formulas written without proofs by the Indian mathematician Srinivasa Ramanujan, found by George Andrews in Cambridge in 1976.
Ramanujan's sum
Ramanujan's sum, also called the Ramanujan sum, is an arithmetic function introduced by Srinivasa Ramanujan in 1916 that sums exponentials over integers coprime to q.
Ramberg–Bäcklund reaction
The Ramberg–Bäcklund reaction is a base-mediated organic reaction converting an α-halosulfone into an alkene with loss of sulfur dioxide, first described by Ludwig Ramberg and Birger Bäcklund in 1940.
Ramesh Giri
Ramesh Giri is a Nepali-born organic and organometallic chemist, born in Chitwan, Nepal, and a professor at Pennsylvania State University known for palladium-catalyzed C–H functionalization and nickel-catalyzed migratory alkene functionalization.
Ramesh Narayan
Ramesh Narayan, born 1950 in Bombay, is an Indian-born American astrophysicist at Harvard known for accretion theory and the Event Horizon Telescope's first black hole image.
Ramification group
A ramification group is a subgroup in a descending filtration of the Galois group of a local field extension, measuring how deeply each automorphism ramifies it.
Ramin Golestanian
Ramin Golestanian, born 1971 in Paris, is a theoretical physicist known for active matter and phoretic microswimmers; he directs Living Matter Physics at MPI-DS Göttingen and is a Royal Society Fellow.
Ramon van Handel
Ramon van Handel is a probabilist and professor of mathematics at Princeton University, known for work on random matrices and convex geometry and a 2012 Presidential Early Career Award.
Ramp compression
Ramp compression is a dynamic high-pressure technique that squeezes materials with continuously rising pressure instead of a shock wave, so samples heat less and can remain solid at extreme pressures.
RAMS (atmospheric model)
RAMS, the Regional Atmospheric Modeling System, is a numerical atmospheric model developed at Colorado State University, formed in 1986 by merging cloud and mesoscale models.
Ramsey cardinal
A Ramsey cardinal is a large cardinal whose finite subsets cannot be 2-colored without a homogeneous set of full size, introduced by Erdős and Hajnal in 1962.
Ramsey interferometry
Ramsey interferometry, also called the method of separated oscillatory fields, is a spectroscopic technique introduced by Norman Ramsey in 1950 that underlies atomic clocks and earned him half of the 1989 Nobel Prize in Physics.
Ramsey number
A Ramsey number is the smallest number of vertices forcing a clique or independent set of given sizes in any graph, with R(3,3) = 6.
Ramsey theory
Ramsey theory is a branch of combinatorics studying how large a structure must be before it is forced to contain a well-organized substructure, named for Frank Ramsey, who proved its central theorem in 1930.
Ramsey's theorem
Ramsey's theorem is a combinatorics result proved by Frank Ramsey in 1930: any coloring of a sufficiently large set's subsets has a large homogeneous subset, founding Ramsey theory.
Ranakah
Ranakah, also called Anak Ranakah, is a lava-dome cluster on western Flores, Indonesia, whose youngest dome formed in a surprise VEI 3 eruption beginning 28 December 1987 after no recorded prior activity; last erupted 1991, alert level 2 since September 2026.
Rand index
The Rand index is a cluster validation measure scoring the similarity of two clusterings as the fraction of point pairs they classify the same way.
Randal D. Koster
Randal D. "Randy" Koster is an American research scientist at NASA's Goddard Space Flight Center who models land-surface processes and led the 2004 Science paper on soil moisture and precipitation.
Randall G. Hulet
Randall G. Hulet is an American atomic physicist at Rice University whose lab was among the first three to achieve Bose-Einstein condensation, in lithium atoms, in 1995.