Siegbahn (Siegbahn), Manne( Swedish physicist, Nobel Prize in Physics, 1924)
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Biography Siegbahn (Siegbahn), Manne
December 3, 1886, Mr.. - September 25, 1978
Swedish physicist Karl Manne Georg Siegbahn was born in the town of ц√rebro in the family of the Chief of the railway station Georg Siegbahn and Emma Sophia Matilda (nee Tsetterberg) Siegbahn. Upon receipt of Lund University (1906) C. immediately carried away by physics. In 1908, Mr.. he began working as an employee at the Institute of Physics at the University, in 1908, Mr.. received a bachelor's degree, and in 1910. Master's degree (having been previously at the universities of Gц╤ttingen and Munich). As an assistant Johannes Rydberg in Lund C. studying electromagnetism and in 1911. defended his doctoral dissertation on measurements of the magnetic field. After summer 1911. in Berlin and the University of Paris, he remains at Lund University as a lecturer in physics.
Intrigued by X-rays, especially after visiting the laboratories in Paris and Heidelberg, P. at the end of 1913. proceed to an independent study of X-rays. Later, he brings to this area of physics fundamental contribution not only for its discoveries, but their instruments, which have enabled them to make precision measurements.
Wilhelm Roentgen called the X-rays (x - unknown) open to them in 1895. mysterious rays, based on electric discharge from the end of vacuum glass tube, opposite the negative electrode (cathode). New X-rays have the amazing ability to pass through opaque objects. After opening Dzh.Dzh. Thomson in 1897. electron, it became clear that the mysterious rays are, when emitted from the cathode fast-moving electron collides with other parts of the tube. Scientists began to suspect that the X-rays can be electromagnetic radiation, such as light and heat, but with greater penetrating power. But because the frequency of X-rays were too large (the wavelengths are too small), . had at that time did not allow devices to detect such familiar phenomena, . as refraction, . polarization, . diffraction and interference (they are observed in the case of visible light),
. First, the possibility of experimenters have been limited to measuring the relative ability of X-rays penetrate through different materials of different thickness - this property rays is called the rigidity. However, the experimenters were able to observe that the various chemical elements used as targets in the X-ray tube to emit the characteristic X-rays of different hardness.
Charles J. Barkla has experienced a number of elements and showed, . that the stiffness (frequency) X-ray radiation increases with increasing atomic weight until, . until it reaches a certain threshold of the atomic weight, . then there is a new family of soft X-rays,
. Faced with more elements of atomic weight, Barkla discovered that the softer X-rays become more stringent. Barkla called these groups of rays K-and L-radiation. Barkla discovered the same polarization of X-rays, which further strengthened the hopes of those who saw the X-ray emission 'close relative' of light.
. Not too subtle methods by which it was found the K-and L-radiation, was not allowed to share X-rays on the frequency or wavelength, ie
. decomposed into spectral lines. To spread out the visible light, you can use a diffraction grating, in which the distance between neighboring strokes compared with the wavelength of light. It was clear that the wavelengths of X-rays in the 100 ... 1000 times smaller than the wavelengths of visible light. Max von Laue pointed out that the distance between atomic planes in the crystal is so small that they can consider the crystal as a kind of diffraction grating for X-ray. The experiment showed the correctness of von Laue, initiating the development of X-ray spectroscopy. U.L. Bragg led a simple formula, . connecting angle, . under which X-rays enter the crystal and leave it, . with a wavelength of X-rays and the distance between the imaginary, . passing through the atoms in the crystal lattice,
. Father Bragg U.G. Bragg built the first true X-ray spectrometer, . using an ionization chamber to measure the X-ray, . emerging from crystal, . and obtained the spectral lines in the wavelength, . that, . he found, . characteristic of the material X-ray source.,
. Young British physicist Henry GJ
. Moseley made using a spectrometer fundamental discovery. Replacing the ionization chamber photodetector, he found a greater number of characteristic lines in the X-ray spectra than Bragg, and showed that these lines in the general case can be divided into two groups. One of the groups, with shorter wavelengths, Moseley identified with the K-radiation Barkla, and another with longer wavelengths - with L-radiation. In contrast to the more diverse optical spectra of X-ray spectra of various elements were similar, but begins with the greater frequency than the heavier atoms are used as X-ray source.
. Moseley discovered that the key to the X-ray spectra is not the atomic weight and atomic number
. According to the model of the atom, first proposed by Ernest Rutherford in 1911. and developed further by Niels Bohr in 1913, the whole positive charge and almost the entire mass of the atom sostredotocheny in the central nucleus. Core is surrounded by electrons, each of which carries a unit negative charge and has very little mass. The number of electrons is equal to the charge of the nucleus, so the atom as a whole is electrically neutral. The atomic weight mainly reflects the mass of the nucleus. The atomic number is equal to the positive charge of the nucleus, or, equivalently, the number of electrons in an atom netralnom. The relationship between frequency (position in the X-ray spectrum) and the atomic number is known as the Moseley and plays an important role in atomic physics.
With. continued study of X-rays in the spirit of the same tradition, extending the measurement lines of K-series Barkla the heavier elements. Crowding scarce funding and lack of necessary equipment in Lund, C. and his disciples were nevertheless carried out a very impressive study. A talented engineer and creator of the devices, C. continually improved the equipment, designing X-ray tubes increasing intensity by making the original vacuum pumps, improving spectrometers to measure the wavelengths with increasing accuracy. When the absorption of longer wavelengths by air has become an obstacle, he built a vacuum spectrometer. When it took more precise measurements, he designed three different spectrometer, adapted to different conditions, in three different wavelength band reception, thereby significantly deviated from the original draft Bragg. Introduced innovations have allowed C. and his students opened up many new lines in the K-and L-series (eg, . set, . that one line in the K-emission actually consists of two almost merged lines), . extend measurements on light and heavy elements, . investigate the X-ray absorption spectra and found two new series, . which he outlined the M and N.,
. Works With
. yielded much new information, almost all the elements (from sodium to uranium) and contributed to a better understanding of atomic structure based on the Bohr model. In this simple model (which has changed dramatically since that time), the electrons orbit around the nucleus is not on any, but only 'allowed' orbits. Turning excited to higher orbits (eg, . by ingestion of the electron beam on the target in the X-ray tube), . electrons then return to a lower orbit, . emitting acquired with excitation energy in the form of discrete portions (photon) of electromagnetic energy,
. The photon energy equals the energy difference between the upper and lower orbit. If the excitation is not too large, the transitions occur between the outer orbits and the emitted photons have relatively low energies. The father of quantum theory of Max Planck showed that the frequency of radiation is proportional to the photon energy. Thus, the low-energy photons are a low-frequency (long wave) radiation, or light. With stronger excitation, such as X-ray tube, the transition involved the inner electrons. There is a deeper 'fall' from an excited orbit, and therefore emitted photons have higher energy. Big energy corresponds to higher frequencies (and shorter wavelengths), and the atom emits X-rays. Precise knowledge of the wavelengths of X-rays allows a deep look into the structure of the atom.
In 1922, Mr.. S. became Professor of Physics at Uppsala University, where pilot studies were more opportunities. In Uppsala, he and his students continued their studies of X-rays, especially in the long-range. In 1924, Mr.. they were able to demonstrate the refraction of the X-ray glass prism, ie. implement the experiment did not turn out to have many researchers, including himself Roentgen. This convinced all those who still had doubts that the X-ray emission is indeed an electromagnetic radiation.
With. was awarded the Nobel Prize in Physics for 1924. 'for the discovery and research in the field of X-ray spectroscopy'. In his Nobel lecture 'The X-ray spectra and structure of atoms' ( 'The X-Ray Spectra and the Structure of the Atoms') C. All the information about what is happening with this area of physical phenomena, transmitted, so to speak, the language of X-rays. This language, we must master if we want to understand and learn how to properly interpret the information received '.
To improve the accuracy of spectrographic measurements, C. and his colleagues have developed a device for manufacturing precision diffraction gratings. With these lattices they have achieved a record of wavelengths to which they have not researched any experimenter. New lattice allowed them to compare the wavelengths of X-rays directly to the wavelengths of visible light and thereby obtain a confirmation of earlier measurements.
When in 1937. at the Royal Swedish Academy of Sciences was founded by the Nobel Institute of Physics, P. was appointed its director. In that position, he continued as the spectroscopic studies, and work on nuclear physics. A year later the institute was built Sweden's first accelerator. During the Second World War the Institute has many scholars of emigrants who have made a considerable contribution to the theoretical research programs.
After the war. expand the subject of the institute and foster the work on the study of nuclear structure. In 1946 and in 1953. he paid a visit to his colleagues in the United States, having been in such academic institutions as the University of California, Massachusetts Institute of Technology and University of Chicago. After retirement in 1964. he stayed at the Nobel Institute, where he continued research.
In 1914, Mr.. S. married Karin Negba. They had two sons. Younger, Kai Siegbahn, also became a renowned physicist. S. died at the age of 91 25 September 1978. Colleagues described him as a man and a simple soul, and his innovative work, in the words of Gerhard Herzberg, 'laid the experimental foundation of atomic theory and will be remembered by generations of physicists'.
With. was a member of the International Committee of Weights and Measures (1937), and from 1938 to 1947. headed the International Union of Pure and Applied Physics. In addition to the Nobel Prize, he was awarded the medal of Hughes (1934) and Rumford medals (1940) Royal Society of London and the medals Daddela Physical Society of London (1948). He was awarded honorary degrees by many universities, including Freiburg and Paris, he was a member of the Royal Society of London, the Royal Society of Edinburgh and the French Academy of