59 years ago today, November 2, 1966 (September 20, 1966 in the lunar calendar), the Dutch American chemist Debye passed away. Peter Joseph William Debye (1884 - 1966) was a Dutch-American physicist and chemist. Born in Maastricht, the Netherlands, on March 24, 1884. He entered the Wyndham University of Aachen in Germany in 1900 and was awarded the title of Electrical Engineer in 1905. In 1906, A. Sommerfeld was invited from Aachen to the University of Munich, and he took Debai with him. In 1908 Debye received his doctorate from the University of Munich. In 1911, he went to Switzerland and succeeded A. Einstein as Professor of Theoretical Physics at the University of Zurich. Later, he served as professor of theoretical and experimental physics at universities such as Utrecht in the Netherlands, Göttingen in Germany, and Leipzig in Germany. The year after the Nazis came to power in 1934, he went to Berlin and was ordered to establish a physics institute for the Kaiser Wilhelm Society, which Debye named Max? Planck Institute for Physics. At that time, Debye still retained Dutch citizenship. Shortly after the outbreak of World War II, the Nazi authorities asked him to become German citizenship, but he flatly refused and went to the United States in 1940 to serve as chairman of the Chemistry Department at Cornell University until his retirement in 1950. He became an American citizen in 1946. He died on November 2, 1966 in Ithaca, New York. Debye was engaged in research on solid state physics in his early days. In 1912 he improved Einstein's formula for the specific heat capacity of solids. When he derived this formula, he introduced the concept of Debye temperature. In 1916, he and P. Scheller developed M.von Laue's method of using X-rays to study crystal structure, using powdered crystals instead of larger crystals that were difficult to prepare. After X-ray irradiation, a diffraction pattern of concentric rings (Debay-Scheller rings) can be obtained on a photographic plate, which can be used to identify the composition of the sample and determine the size of the unit cell. In 1926, Debye proposed the method of adiabatic demagnetization cooling with paramagnetic salts. With this method, low temperatures below 1K can be obtained (see Ultra-Low Temperature Technology). Debye has also made important contributions to the theory of polarized molecules in salt solutions, molecular dipole moments and molecular structure. He quantitatively studied the connection between solute and solvent molecules and explained some anomalies in dense solutions. His work on molecular polarization has led to a leap forward in people's understanding of the arrangement of atoms in molecules. In solution theory, he introduced a characteristic length called the Debye length, which describes the farthest distance that the electric field of a positive ion can affect an electron. The Debye length has now become a basic physical quantity in solution theory and plasma physics. Debye won the 1936 Nobel Prize in Chemistry for his outstanding contributions to X-ray diffraction and molecular dipole moment theory.