Gorter Discovered The Nuclear Magnetic Resonance

Credit for the discovery of NMR goes to Isidor Isaac Rabi, who received the Nobel Prize in Physics in 1944. Working at New York City’s Columbia University in the 1930’s, Rabi and his team were attempting to measure the magnetic properties of various nuclei including hydrogen, deuterium, and lithium. Using a modification of Otto Stern’s apparatus, Rabi described how nuclei could be induced to flip their principal magnetic orientation by an oscillating magnetic field. This idea was originally proposed by Dutch physicist Cornelius J. Gorter in 1936 (one year before Rabi’s successful demonstration), but Gorter was unable to validate this phenomenon due to limitations of his experimental setup. Gorter is sometimes known as “the man who almost discovered NMR.”

Rabi’s method involved using an electromagnet of approximately 0.2T and a hairpin coil producing an oscillatory RF-field of about 3.5 MHz. The RF-field was maintained at constant frequency and the main magnetic field was varied by changing its current. Rabi then passed a “molecular beam” of lithium chloride (LiCl) molecules through a vacuum chamber and subsequently into the magnetic apparatus. In 1938 he and his team reported energy absorption/resonance peaks for both Li and Cl as predicted. Rabi named this phenomenon “nuclear magnetic resonance.”

By – HOD – Dr.J.P.Juyal
Chemistry Department
Uttaranchal (P.G.) College Of Bio-Medical Sciences & Hospital