 |
Willem KeesomDutch physicist.
Date of Birth: 21.06.1876
Country:  Netherlands |
Content:
- Willem Hendrik Keesom
- Collaboration with Kamerlingh Onnes
- Utrecht University and Diffraction Studies
- Return to Leiden and Low-Temperature Research
- Discovery of Helium II
- Record-Breaking Temperatures and Helium II Properties
- Later Career and Legacy
Willem Hendrik Keesom
Early Life and EducationWillem Hendrik Keesom, a Dutch physicist, was born on June 21, 1876, on the island of Texel. He completed his studies at the University of Amsterdam in 1900, where he was mentored by renowned physicist Johannes Diderik van der Waals. In 1904, Keesom earned his doctorate for his work on the isotherms of oxygen and carbon dioxide mixtures.
Collaboration with Kamerlingh Onnes
From 1900 to 1909, Keesom worked at Leiden University as an assistant to physicist Heike Kamerlingh Onnes. In 1908, together with Onnes, he made history by first liquefying helium. In 1912, Keesom contributed an extensive review on the equation of state to a mathematical encyclopedia.
Utrecht University and Diffraction Studies
In 1909, Keesom moved to Utrecht University, where he conducted groundbreaking experimental research. He investigated the diffraction of X-rays on liquid molecules and determined intermolecular distances. In 1917, he became a lecturer, and in 1918, he was appointed professor of experimental physics.
Return to Leiden and Low-Temperature Research
In 1923, Keesom returned to Leiden University as a professor. In 1926, he became the director of the cryogenic laboratory, succeeding Kamerlingh Onnes. At Leiden, Keesom resumed his low-temperature research. He precisely measured the boiling point, vapor pressure, and other physical properties of liquid helium.
Discovery of Helium II
In 1928, in collaboration with M. Wolfke, Keesom made a significant discovery. They identified a phase transition in liquid helium at 2.19 K, characterized by a discontinuous change in thermal conductivity. This finding implied the existence of two distinct modifications of helium at low temperatures: helium I above the critical temperature and helium II below it.
Record-Breaking Temperatures and Helium II Properties
Between 1931 and 1932, Keesom reached a record-low temperature of 0.71 K by pumping off vapor from liquid helium. In 1935, he observed the unusually high thermal conductivity of helium II, later attributed to its superfluid properties by Pyotr Leonidovich Kapitza.
Later Career and Legacy
In 1938, Keesom obtained the first X-ray diffraction pattern of solid helium. He published a monograph on the physical properties of helium at low temperatures in 1942 and retired in 1945. Keesom passed away in Leiden on March 24, 1956, leaving a lasting legacy in the field of low-temperature physics.
