The Nobel Prize in Chemistry 1944 was awarded to Otto Hahn "for his discovery of the fission of heavy nuclei".
 

Otto Hahn received his Nobel Prize one year later, in 1945. During the selection process in 1944, the Nobel Committee for Chemistry decided that none of the year's nominations met the criteria as outlined in the will of Alfred Nobel. According to the Nobel Foundation's statutes, the Nobel Prize can in such a case be reserved until the following year, and this statute was then applied. Otto Hahn therefore received his Nobel Prize for 1944 one year later, in 1945. In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts, often producing free neutrons and photons , as well.
 

An atomic nucleus is a very small thing. Rutherford found that its diameter is about ten thousand times smaller than that of the atom, or about one billionth (10-12) of a centimetre. Later, Joliot and his wife Irène Joliot-Curie studied in greater detail what happens when different kinds of elements are exposed to radiation by positive particles rich in energy. Fermi used the neutron discovered by Chadwick as a projectile to obtain nuclear syntheses. All these researches into nuclear chemistry were concerned with relatively slight modifications to the mass of the reactive nuclei. Hahn's discovery caused great surprise and evoked lively interest among the world's scientists.