 Erwin Hahn

Erwin Hahn discovered spin echo signals, in which radiofrequency pulses restore an observable signal from nuclear spins that have apparently lost phase coherence. A spread of static magnetic fields makes different spins precess at different rates; suitable later pulses allow this reversible dephasing to refocus. The echo amplitude then probes relaxation and diffusion, rather than being determined solely by static field inhomogeneity. His 1950 analysis made pulsed nuclear magnetic resonance a method for distinguishing different causes of signal decay.^[ref]

A physicist who developed spin echo methods and studied nuclear magnetic resonance and optics.^[ref]

Erwin Hahn is a notable physicist best known for his work in the field of magnetic resonance and for the development of several techniques in nuclear magnetic resonance (NMR) spectroscopy. One of his most significant contributions is the Hahn echo, a technique that enhances the resolution and sensitivity of NMR experiments by refocusing the spins of nuclei that experience dephasing due to various interactions.