(1881-1958) American Experimentalist, Particle Physicist
Clinton Joseph Davisson shared the 1937 Nobel Prize in physics with George Thomson as the first to observe experimentally the wave nature of the electron, thereby confirming louis-victor-pierre, prince de broglie’s theory of the wave-particle duality of subatomic particles.
He was born in Bloomington, Illinois, on October 22, 1881, to Joseph Davisson, an artisan, and Mary Calvert, a schoolteacher. He attended Bloomington public schools and, in 1902, won a scholarship on the basis of his mastery of mathematics and physics to the University of Chicago. There he studied under robert andrews mil-likan, the first physicist to measure the charge of the electron, who was impressed with his abilities. For financial reasons, however, Davisson had to leave school and return to his hometown, where he began working for the telephone company. In 1904, Millikan came to his rescue by recommending him for an assistantship in physics at Purdue University. In June of that year, he was able to return to Chicago, where he remained until, in 1905, once more thanks to Millikan, he became a part-time instructor of physics at Princeton University. Continuing to study for his degree, he earned a B.Sc. in 1908, from Chicago. In 1911, a fellowship in physics at Princeton enabled him to complete a Ph. D. from Chicago, for his thesis “The Thermal Emission of Positive Ions from Alkaline Earth Salts.” That same year, he married Charlotte Sara Richardson, the sister of his thesis adviser; they would have three sons and one daughter together.
From 1912 to 1917, Davisson was an instructor in the physics department at the Carnegie Institute of Technology in Pittsburgh. During this period he spent the summer of 1913 at the prestigious Cavendish Laboratory, Cambridge University, working under joseph john (j. j.) thomson, the discoverer of the electron. When the United States entered World War I in 1917, Davisson tried to enlist in the army but was rejected. He worked instead for the engineering department of the Western Electric Company, which later became Bell Telephone Laboratories, in New York City. Initially this was a war assignment, but Davisson decided to stay on, resigning his position as assistant professor at Carnegie.
While he was working on an experiment involving the reflection of electrons from metal surfaces under electron bombardment in April 1925, an accidental explosion caused a nickel target he was studying to become heavily oxidized. He removed the coating of oxide by heating the nickel. As he continued working, he made an intriguing observation: a change had taken place in the angle of reflection of electrons from the nickel surface. Davisson and his assistant Lester Germer sought a possible cause and finally attributed the change to the recrystallization of the nickel; it was probable, they conjectured, that in the reheating process many small crystals in the nickel surface had converted into several large crystals. The following year, however, while enjoying a “second honeymoon” with Charlotte in London, Davisson attended a conference that dealt with the new rel-ativistic particle-wave theory of the electron developed by de Broglie. In his theory, the French physicist had found a simple relationship between the velocity of the particle and the wavelength of the “wave-packet” associated with this particle. The greater the velocity of the particle, the shorter the wavelength. If the velocity of the particle is known, it is then possible, by using de Broglie’s formula, to calculate the wavelength, and vice versa. Once aware of de Broglie’s revolutionary new theory that electrons have wave properties, Davisson no longer found the recrystallization hypothesis so persuasive. He knew that X-ray diffraction had already been observed in crystals. Was it not likely, he reasoned, that the effects he had observed were due to the diffraction of electron waves in the planes of atoms in the nickel crystals?
Upon his return to the United States, he and Germer devised an experiment using a simple nickel crystal. The atoms were in a cubic lattice with atoms at the apex of cubes, and the electrons were directed at the plane of atoms at 45 degrees to the regular end plane. Electrons of a known velocity were directed at this plane, and those emitted were recorded by an electron detection apparatus. In January 1927, the results they obtained indicated that for incident electrons of a certain velocity, electron diffraction occurred, producing outgoing beams that could be related to the interplanar distance. The wavelength of the beams could then be determined and used, together with the known velocity of the electrons, to confirm de Broglie’s hypothesis.
Four months later, George Thomson, the son of J. J. Thomson, working independently at Aberdeen University, Scotland, with different experimental apparatus, made the same discovery. For their definitive confirmation of the particle-wave duality of subatomic particles, Davisson and Thomsom would share the 1937 Nobel Prize in physics.
From 1930 to 1937, Davisson focused on the theory of electron optics, seeking ways to apply it to engineering problems. He also studied the scattering and reflection of very slow electrons by metals. During World War II, he investigated the theory of electronic devices, as well as a series of problems in the field of crystal physics.
Davisson remained with Bell Telephone Laboratories for 29 years, retiring in 1946, when he became visiting professor of physics at the University of Virginia, Charlottesville. He retired in 1949 and died in Charlottesville, on February 1, 1958, at the age of 76.
Davisson’s groundbreaking experiments, by confirming the de Broglie hypothesis that a quantum wave-particle duality is inherent in matter, opened the door to the new world of quantum mechanics and elementary particle physics.
