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JEAN FRÉDÉRIC JOLIOT & IRÈNE CURIE

In 1925, Frédéric Joliot accepted the position of special assistant to Marie Curie. The next year, he married Marie's daughter, Irène, forming one of the most remarkable scientific partnerships of all time: Frédéric served the role of chemist, Irène that of physicist. Unfortunately, the early stage of their careers was defined by failure rather than success. Not only did they fail to discover the neutron, misidentifying it as a gamma ray, they also just missed discovering the positron. Later on, however, it was their observations of these very particles that led to their discovery of artificial radioactivity, which is considered to be their greatest triumph. Irène and Frédéric had noted that the bombardment of aluminum with alpha particles resulted in the emission of neutrons and positrons. As expected, the neutrons were emitted only as long as the aluminum was being bombarded by alpha particles. What astonished Frédéric and Irène was the continued emission of positrons long after the alpha source had been removed from the target. Immediately, Frédéric and Irène performed careful analyses which showed that the alpha bombardment had produced a positron-emitting radionuclide of phosphorous from the aluminum. Not only had they produced the first artificial radionuclide, they were the first to experimentally confirm transmutation, the conversion of one element into another element! Up to this point, the only radioactive materials available for medical and scientific research were those that occurred naturally. Now a method was available for creating a wide new variety of radioisotopes. The impact was immense, and for this discovery the Joliot-Curies won the 1935 Nobel Prize for chemistry. Later, during WW II, they helped hamper German efforts to develop an atomic bomb by ensuring that the entire stock of heavy water from the Norsk Hydro Plant was secured and shipped to Britain before France and Norway came under German control. After the war, they made major contributions to the construction of France's first nuclear reactor.

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