Louis Dunoyer de Segonzac

Background

Louis Dunoyer de Segonzac was born on November 14, 1880, in Versailles, France. He was the son of Anatole Dunoyer, a founder of the École des Sciences Politiques in Paris, and Jeanine Roquet.

Education

As a youth, Dunoyer placed first in the general physics competition and was second on the admissions list of the École Polytechnique and first on that of the École Normale Supérieure. He chose to attend the latter (1902-1905), which oriented him toward teaching and research.

Career

Dunoyer placed first in the physics agrégation in 1905 and in that year was an assistant to P. Langevin at the Collège de France. His first research concerned the difficulties of compensating compasses in iron and iron-clad ships. This work furnished the subject for his doctoral thesis' and took concrete form in the dygograph and the type of electromagnetic compass that was mounted in Lindbergh’s Spirit of St. Louis.

A Carnegie scholar in the laboratory of Marie Curie in 1909, Dunoyer conducted the fundamental experiment on molecular beams in 1912. Originally designed to verify the kinetic theory, the experiment also resulted in the preparation of thin films of alkali metals. This experimental demonstration of the kinetic theory of gases was the origin of the preparation of thin films by thermal vaporization and of the studies of the properties of atoms and molecules by the so-called molecular ray method.

In 1913 he was appointed deputy professor at the Conservatoire National des Arts et Métiers. He studied the surface resonance of sodium vapor with R. W. Wood in 1914.

Dunoyer also served as an aviation officer and inspector until he was wounded. He became interested in meteorology and aerial navigation and invented a bombsight.

Dunoyer became a lecturer at the Institut d’Optique in 1919. He was a physicist at the observatory of Meudon from 1927 to 1929 and professor at the Institut d’Optique from 1921 to 1941. He participated in the founding of the Société de Recherches et de Perfectionnements Industriels, and while secretary-general of the Société Française de Physique he devised a special lens for the illumination of atomic beams.

A glassblower and remarkable technician, he improved the procedures of Wolfgang Gaede (1913) and of Langmuir (1916) and developed various diffusion pumps and devices for measuring very low temperatures.

Simultaneously Dunoyer pursued his research on photoelectricity and the construction of photoelectric cells; the first application (1925) was to talking movies, where a potassium cell was employed.

In 1935 Dunoyer’s studies on thermal vaporization in a vacuum enabled him to construct the first aluminized mirrors. From 1941 to 1945 he was titular professor at the Sorbonne and director of the Institut de Chimie Physique, where he taught a remarkable course on the kinetic theory of gases. Dunoyer published seven articles between 1949 and 1956 in Le eide, the Société des Ingénieurs du Vide's journal.

Achievements

• Louis Dunoyer de Segonzac is remembered as a distinguished physicist who received many awards and honors for his research.
  
  In 1908 he won the Prix Extraordinaire de la Marine for his research in magnetism.
  
  In 1912 Dunoyer was awarded the Subvention Bonaparte for his work on the fluorescence of pure sodium vapor and for the complete investigation of the fluorescence and absorption spectra of the alkaline metals.
  
  In 1913 he won the Prix Becquerel for his research on the electrical and optical properties of metallic vapors, notably of sodium vapor. Dunoyer became chevalier of the Legion of Honor, receiving the Croix de Guerre in 1915.
  
  In 1918 he was awarded the Prix Danton for his work on radiant phenomena. He was awarded the the Subvention Loutreuil in 1925. He won the Prix Valz in 1929 for his research on the spirit level and on photoelectric cells. In 1930 he was awarded the Subvention Loutreuil for the continuation of his research on photoelectric cells.

Works

• book

  • Patent Application Number 18,615 for Improvements in and Relating to Mariners' Compasses 1909

Membership

On February 10, 1937 Dunoyer was elected artist member of the Bureau des Longitudes, replacing Louis Jolly. He was also named honorary president of the Société des Ingénieurs du Vide.

• Bureau des Longitudes , France

  1937

• Société des Ingénieurs du Vide , France

Personality

The Société des Ingénieurs du Vide dubbed Dunoyer “Grandfather of the Vacuum.”

Connections

Dunoyer married Jeanne Picard, the daughter of Émile Picard, on June 4, 1907. They had two sons, whose studies Dunoyer supervised himself.

Father:

Anatole Dunoyer de Segonzac

Mother:

Jeanine Roquet

Spouse:

Jeanne Picard

Brother:

Charles Dunoyer de Segonzac

colleague:

Paul Langevin

colleague:

Robert Williams Wood

References

• Mathematicians at War
  2009
• Frédéric Joliot-Curie
  2000
• L'Action Francaise
  2008
• Dawn of the Electronic Age
  1914