Herbert A. Hauptman

Herbert A. Hauptman was an American mathematician and crystallographer who developed direct methods for determining crystal structures from X-ray diffraction data. He shared the 1985 Nobel Prize in Chemistry with Jerome Karle.

Direct methods: A family of crystallographic techniques that derives atomic arrangements from measured diffraction intensities. Hauptman and Jerome Karle transformed these methods into a practical route to solving crystal structures.
Jerome Karle: An American chemist and crystallographer who developed direct methods with Herbert A. Hauptman and shared the 1985 Nobel Prize. Karle was Hauptman’s principal collaborator in developing the equations recognized by the Nobel committee.
X-ray diffraction: The scattering of X-rays by matter, producing patterns that reveal periodic structures. Diffraction patterns posed the inverse problem that Hauptman’s work sought to solve.
Crystal structure determination: The process of inferring the atomic arrangement of a crystal from experimental measurements. Hauptman’s methods made this process feasible for many structures without heavy-atom derivatives.
Isomorphous replacement: A crystallographic phasing method that compares a native crystal with derivatives containing heavier atoms. Unlike this experimental strategy, direct methods seek phase information from relationships within native diffraction data.
X-ray crystallography: A technique that uses X-ray diffraction by crystals to determine atomic and molecular structures. Its diffraction measurements supply the data that Hauptman’s methods interpret.
Isidor Fankuchen: An American crystallographer who directed Hauptman’s doctoral research at the Polytechnic Institute of Brooklyn. Fankuchen supervised Hauptman’s early crystallographic research and helped shape his scientific direction.
Fourier transform: A mathematical operation that represents a function as a combination of sinusoidal components. Crystallographers use Fourier synthesis to convert structure factors into electron-density maps.
Small-molecule crystallography: The determination of atomic structures in crystals of molecules smaller than macromolecules. Direct methods became especially effective for solving small-molecule structures from diffraction data.
Anomalous dispersion: A diffraction effect used to determine phases by exploiting wavelength-dependent scattering from certain atoms. It offers experimental phase information rather than relying solely on Hauptman’s probabilistic relationships.

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