Dudley Herschback is a US physical chemist who used intersecting beams of atoms or molecules to study atomic and molecular motions in chemical changes and to record the energy of the reactant and product molecules. He also invented devices to identify the products. Herschback shared the 1986 Nobel Prize in Chemistry with Yuan Tseh Lee and John Polyani for their work in chemical reaction dynamics. They originally used their new technique for the reaction between potassium atoms and iodomethane (methyl iodide) molecules and later employed it for numerous other systems. Hershback was professor of chemistry at Harvard and chairman of that department from 1977–1980.