 The Purcell group at Harvard University and the Bloch group at Stanford University independently developed NMR spectroscopy in the late 1940s and early 1950s.Edward Mills Purcell and Felix Bloch shared the 1952 Nobel Prize in Physics for their discoveries.When placed in a magnetic field, NMR active nuclei (such as 1H or 13C) absorb electromagnetic radiation at a frequency characteristic of the isotope.