Date of Birth: 07/22/1887
Place of birth: Hamburg
German physicist Gustav Ludwig Hertz was born in Hamburg in the family of lawyer Gustav Hertz and Augusta (Arning) Hertz. His uncle Rudolf Heinrich Hertz was one of the most eminent physicists of the late XIX century. After receiving his secondary education in Hamburg Iohanneume, GA in 1906, he entered the University of Gottingen, where he studied mathematics and mathematical physics of David Hilbert and Carl Runge. He then studied at the University of Munich, Arnold Sommerfeld, where he met with the then new quantum theory, and the University of Berlin at the James Franck and Robert Paul. There he became interested in experimental physics. In 1911 he defended his thesis at the University of Berlin on the infrared absorption of carbon dioxide and received his doctorate.
In 1913 he was appointed assistant at the Physics Institute at the University of Berlin, where he and Frank began to study the changes of energy in a collision with an electron of an atom. Their work was a direct confirmation of the atomic model proposed not long before Niels Bohr, although they were not yet familiar with it.
According to Bohr`s theory, electrons could revolve around the nucleus only "allowed" orbits, each of which corresponds to a particular energy state of the electron. According to Bohr, the electron absorbing a discrete portion of energy, or quanta, "jumps" into the orbit corresponding to higher energy and located farther from the nucleus. In the transition from the higher to the lower orbit of the electron emits a photon. The photon energy is equal to the energy difference between the orbits. Bohr`s model will partially explain the mysterious before the line spectra of the elements. When the gas is turned on by the experimenter, for example by passing it through an electrical discharge, the atoms dump excess energy in the form of emission - light. Atoms of each element emit light of a certain color, the relevant characteristic of the element frequency and wavelength. The spectroscope splits the frequency and receive a series of colored lines, or a line spectrum is characteristic of the element. The founder of the quantum theory of Max Planck in 1900 proved that the frequency is proportional to the photon energy. Thus, poteorii Bora, each spectral line corresponds to the energy difference between the two orbits. Thus, the line spectra serve as a key to the atomic structure.
By applying a positive voltage to the electrode opposite to the electron source, and Frank G. accelerated electrons (negatively charged particles) in a sealed tube. The electrons, the maximum kinetic energy is known (it is equal to the product of the potential difference and charge of the electron), and can be adjusted, flew through the highly rarefied mercury vapor. The other electrode could detect the electron energy loss due to collisions with mercury atoms. It has been found that the energy losses are negligible, while the potential difference reaches 4.9 volts. This discovery showed that the energy absorbed by the atom only certain portions of confirmed one aspect of Bohr`s theory. Similar results were obtained for the other gases such as helium and neon. G. and Frank calculated the frequency corresponding to the quantum of energy equal to the electron energy of 4.9 electron volt, and found that it coincides with the frequency of one of the lines of the line spectrum of mercury (in the UV range). But as Bohr`s theory while "celebrated" only a few months, and much of it was still unclear, H. and Frank misinterpreted 4.9 volts as the ionization potential, ie, as the energy required to extract an electron from the atom. The loss of an electron violates the neutrality of the atom - the balance between the negative electrons outside the nucleus and positive protons in the nucleus - and leads to a positively charged ion. G. and Frank believed that ultraviolet mercury line emitted by the capture of an electron and ion filling vacancies. The main problem was that the Bohr model predicted ionization potential of 10.36 volts.
After some confusion had reached a better understanding of Bohr`s model, and then it turned out that the line in question is consistent with electron transfer between the two lower orbits in the spectral series, rather than the loss of the outer electron and its capture. The value of 4.9 volts was not the ionization potential and the excitation potential, ie, energy (or quantum), necessary for the excitation of the electron - its transition from one energy level to another, higher, without departing from its atom. By optimizing the experimental technique. , Frank and other researchers measured several other (higher) excitation potential. It turned out that the potential values ??obtained correspond to lines observed in the spectrum of mercury. It was possible to confirm and Bohr predicted value of the ionization potential. G. Frank and became the first physicist who could directly measure the energy of a photon.
Later, Frank admitted that they "are not appreciated the fundamental importance of Bohr`s theory, so that did not even mention it in his article." However, Bohr and his associates understood the importance of experimentation and the Frank G. and repeatedly referred to them in support of their ideas.
In 1926, H. and Frank was awarded the Nobel Prize in Physics in 1925 "for the discovery of the electron collisions with atoms of the laws." Introducing the winners, KV Oseen of the Royal Swedish Academy of Sciences said: "Until recently, nobody even thought that the atom can exist in various states, each of which is characterized by a certain level of energy, and that these energy levels are determined by the spectral lines ... Bohr theory put forward the hypothesis ; methods of experimental verification of the developed and James G. Frank. "
During the First World War and G. Frank served in the German army. In 1915 G. was seriously injured. After long-term treatment in 1917 he became a freelance lecturer at Berlin University. From 1920 to 1925 he worked in the physics laboratory at the plant of the company "Philips" light bulbs in Eindhoven (the Netherlands). "Philips" was one of the first private companies that fund basic research. In 1925, he became professor of physics at the University of Halle and the director of the Physics Institute at the same university. Three years later, he returned to Berlin as Director of the Physics Institute at the Technical University of Charlottenburg. Because scientific advances G. this period, the most significant is the development of the gas diffusion method of separating isotopes of neon.
When in 1933 to power in Germany, the Nazis came, G. refused to take an oath of allegiance to the Fuhrer and in 1934 was forced to resign. By the end of the Second World War, he served as director of the research laboratory of the company "Siemens and Halske" in Berlin. It is unclear why H., whose father was a Jew, and the first wife was against Nazism, was allowed to occupy such an important post.
After the war, he was in a group of German scientists who were sent to the Soviet Union under a contract for ten years. During his visit to the United States in 1939, G. told his friends that the level of physical research in the US is very high, but he feels that it would be more useful in the Soviet Union. G. hoping that his family will be able to integrate into Soviet society. But G., and other German scientists were isolated in a laboratory complex. In the Soviet Union he headed research on atomic energy and radar in the laboratory, which was in Sukhumi. His method of isotope separation he improved so much that it became possible to carry out the separation on an industrial scale. In 1955 he returned to Leipzig, where he became a professor at the Karl Marx University. As Director of the Physics Institute at the University of Leipzig, he headed the construction of the new building of the Institute to replace the destroyed during the war. In 1961 he retired and settled in East Berlin, where he spent the last 14 years of his life.
In 1919 he married Ellen Dilman. They had two sons, both later became physicists. In 1943, two years after his first wife`s death, he entered into a second marriage with Charlotte Yollass. G. was a reserved man, and his opinions and hobbies little is known, except that he was quite a professional photographer.
In addition to the Nobel Prize G. he has received many honors, including the Max Planck Medal of the German Physical Society and the Lenin Prize of the USSR government. He was elected a member of the German Academy of Sciences in Berlin and Gottingen Academy of Sciences, as well as the Academies of Sciences of Hungary, Czechoslovakia and the Soviet Union.