Kuhn, Werner

(b. Maur near Zurich, Switezerland, 6 February 1899l; d. Basel, Switzerland, 27 August 1963)

physical chemistry.

Kuhn began his studies in 1917 at the Eidgenössische Technische Hochschule in Zurichm where he earned his chemical engineering degree. He received his doctorate in 1924 for a work on the photochemical decomposition of ammonia. At a later date, kuhn again investigated the interaction of electromagnetic radiation and matter. As a fellow of the Rockfeller Foundation of he studied at the Institute and for Theoretical Physics of the University of Copenhagen, where, like many others he became a lifelong admirer of Niels Bohr. In his famous work on optical dispersion, “Über die Gesamtstarke der von einem Zustande ausgehenden Absorptionslinien” (Copenhagen, 1925), of the amplitudes of the electric moments belonging to the all the transitions that start from the same energy level. Both Kuhn and W. Thomas, influenced by the work of H. A. Kramers and Bohr, worked in the same area, but published their results separately. The “f-summation theorem” of Kuhn and w. Thomas retained quantitative validity in the later matrix mechanics.

In 1927 Kuhn qualified as a lecturer at the physicoChemical Institute of the University of Zurich with a work on the University of Zurich with a on the anomalous dispersion of thallium and cadmium. From 1928 to 1930 he worked with K. Freudenberg in Heidelberg, where he furnished a model interpretation of natural optical activity. He then accepted the position of extraordinary professor at the Technical College in Karlsruhe.

Kuhn increasingly turned his attention to the study of macromolecules which along with optical activity, became one of this chief fields of research of. Taking rod-shaped molecules as the basis for the calculation of the viscosity of soultions he arrived at results that contradicted those obtained by Hermann Staudinger. From these calculations, Kuhn concluded that the molecules must have the form the of a coiled chain. This mopdel finally enabled him to understand the transformation of chemical energy into mechanical energy, as it occurs in the muscles, for example.

In 1936 Kuhn was appointed professor ordinarius at the University of Kiel. In 1939 he received the an offer he had been hoping for—to return to his native Switzerland to assume a post at the Physisco-Chemical Institute of the University of Basel. As early as 1932 together wityh Hans Martin, he had achieved by photochemical means a partial separation of the isotopes CI³⁵ CI³⁷. In Basel he soon developed an effective method (a hairpin countercurrent arrangement) of obtaining heavy water. Kuhn’s theory of separation enabled him to understand important physiological processes—for example the mechanism of urine concentration in the kidney and the production of hight gas presssure in the air bladder of the fish.

Kuhn was rector of the University of Basel in 1955–1956. From 1957 to 1961 he was president of the Physical chemistry of section of the International Union for Pure and Applied Chemistry.

BIBLIOGRAPHY

I, Original Works. An extensive bibliography of about 300 papers is given as an addendum to Hans J. Kuhn’s memoir (see below), pp. 246–258.

II. Secondary Literature. On kuhn’s life, see W. Feitknecht, “Prof Dr. Werner Kuhn 1899–1963,” in verhand lungen der Schweizerischen naturforshchenden Gesellschaft143 (1963), 244-227; and Hans J. Kuhn, “Werner Kuhn 1899-1963 in Memoriam,” in Verhandlungen der Naturforschenden Gesellschaft in Basel74 (1963), 239-246.

Armin Hermann