Hendrik antoon lorentz won the 1902 Nobel Prize in Physics. 1928) and Zeeman (Pieter Zeeman 1865? 1943) in recognition of their special contribution to the study of the influence of magnetism on radiation phenomena.
The influence of magnetism on radiation phenomenon is also called Zeeman effect, which was discovered by Zeeman in 1896. It is another effect that reflects the electromagnetic characteristics of light after Faraday effect and Kerr effect. Zeeman effect further involves the radiation mechanism of light, so it is considered as one of the most important discoveries in physics after X-ray.
Lorenz is a Dutch physicist. His main contribution is the establishment of classical electronic theory, which can explain a series of electromagnetic phenomena in matter and some effects of matter moving in electromagnetic field. Because Zeeman effect was explained from Lorentz theory in time when it was discovered, the electron charge-mass ratio determined from it was on the same order of magnitude as that obtained by J·J· Thomson with cathode ray, and they were mutually verified, so Lorentz and Zeeman shared the Nobel Prize in Physics in 1902.
Zeeman is also Dutch. 1885 After entering Leiden University, he worked with Lorenz for many years and served as Lorenz's teaching assistant. Zeeman is very familiar with Lorenz's electromagnetic theory, and his experimental technique is superb. He won the gold medal in 1892 for his careful measurement of Kerr effect, and received his doctorate in 1893. When he studied the influence of magnetic field on spectrum, he benefited from Lorenz's guidance and Lorenz's theory, and made a great discovery. Here is the discovery of Zeeman effect.
Zeeman was originally inspired by Faraday's work. 1845, Faraday made plane polarized light pass through glass under the action of strong magnetic field, and it was found that the polarization plane of light rotated, which further confirmed that this was the common property of many substances. In 1876, Kerr discovered after 1875 that the glass sheet has birefringence effect on light under strong electric field (Kerr electro-optic effect), and he also found that when plane polarized light is vertically incident on the polished electrode of electromagnet, the reflected light becomes elliptically polarized light (Kerr magneto-optical effect). These effects are of course excellent evidence of the electromagnetic characteristics of light. Therefore, the interaction between electricity, magnetism and light has become the object that physicists pay close attention to at the end of 19.
Around 1895, Zeeman suspended the research on Kerr magneto-optical effect to see if the magnetic field has any influence on the spectrum of sodium flame. Although the experiment was unsuccessful, I later learned that Faraday had done it himself in his later years. He thought that a great scientist like Faraday attached importance to this experiment, and it must be worth doing seriously, so he made up his mind to do it again with the best equipment at that time. He had an idea at that time, when the magnetic force acts on the flame, whether the light period emitted by the flame will change. Such a thing really happened. Zeeman glued asbestos strips with salt, put them into hydrogen-oxygen flame between electromagnet poles, and tested the flame light with Roland grating (note: concave grating was the best spectrometer at that time). When the electromagnetic circuit is connected, the two spectral lines of D (note: sodium yellow spectral lines D 1 and D2) become wider.
The broadening of spectral line can be considered as a known effect of magnetic field on flame, which leads to the change of density and temperature of sodium vapor. Zeeman adopted a method of strongly heating sodium in a common porcelain tube. Both ends of the porcelain tube were sealed with parallel glass plates, with an effective area of 65,438+0 cm2. The tube is placed horizontally in the magnetic field and perpendicular to the magnetic field line. The light of the arc lamp passes through it. The absorption spectrum shows a D double line. The porcelain tube keeps rotating along the axis to avoid temperature change. Excitation and excitation, and immediately broaden the spectral line. It is proved that the magnetic field changes the period and frequency of sodium light.
At first, Zeeman thought that the frequency change of light may be due to the acceleration and deceleration forces between atoms and ether molecules; Later, Lord Kelvin suggested to Zeeman that perhaps the change of frequency can be explained by combining a fast rotating system with a double pendulum. However, these explanations are not satisfactory, so Zeeman turned to Professor Lorenz's electronic theory to explain. This theory holds that all objects have charged small molecular units; All the electrical processes come from the balance and movement of these "ions" (note: no electrons were found at that time), and light waves are caused by the vibration of "ions". In Zeeman's view, the direct force on "ions" in the magnetic field is enough to explain this phenomenon.
Zeeman wrote this idea to Professor Lorenz, who instructed Zeeman to calculate the movement of ions. He also pointed out to Zeeman that if this theory is used correctly, it should have the following results: the light emitted from the edge of the widened spectral line should be circularly polarized in the direction of the magnetic field line, which can further lead to the calculation of the ratio e/m of the charge carried by ions to their mass. Zeeman used quarter-wave plate and analyzer, and found that the edge of spectral line widened when magnetic field was applied, which was circularly polarized light viewed from the direction of magnetic field lines.
On the contrary, if viewed from the direction perpendicular to the magnetic field lines, the edge of the broadened sodium spectrum shows plane polarized light, which is consistent with Lorenz theory. Just a few months before Just Thomson announced the discovery of electrons, Zeeman also estimated the charge-mass ratio e/m of this charged particle according to the broadening of the spectral line, which is of the order of107 cgsm/g. J·J· Thomson also measured the charge-mass ratio of cathode rays, which is in the same order of magnitude as that measured by Zeeman. This result has become an important evidence of the existence of electrons.
In this way, Zeeman not only gave a reasonable explanation for the phenomenon of spectral broadening he discovered, but also proved the existence of ions (note: electrons), which provided convincing experimental verification for Lorenz's electronic theory.
In 1896, Zeeman further judges the positive and negative charges of radiation-producing "ions" according to the optical rotation direction of circularly polarized light. At first, he mistakenly thought it was positively charged, but after one year it was corrected to be negatively charged.
According to Lorenz's electromagnetic theory, we can infer the following results: from the direction perpendicular to the magnetic field, the spectral lines should be divided into three; Seen from the direction parallel to the magnetic field, the spectral line should be split in two. Zeeman increased the magnetic field to about 30 thousand gauss, and finally observed double lines and three lines.
Zeeman was very lucky to further confirm Lorenz's theoretical vision, because he later learned that only the pedigree of singlet can get the expected results of Lorenz's theory.
Zeeman's results are consistent with Lorenz's theory, which is not only a great success of Lorenz's theory, but also makes Zeeman's work quickly recognized. However, Zeeman and his contemporaries believed in this theory too much, which also caused some difficulties. The difficulty mainly comes from the abnormal Zeeman effect which is inconsistent with the theory.
Zeeman himself has seen four splits and six splits in the experiment. He didn't face up to these phenomena that were inconsistent with Lorenz's theory, but was bent on bringing them into the orbit of Lorenz's theory. For example, he explained that the quadruple line is that one of the triplets "self-corrodes" into two, while the quadruple line is that each triplet "self-corrodes" into two.
1897, Zeeman transferred to the University of Amsterdam to teach and continued to experiment with the equipment there. The main tool is concave grating. However, because the whole set of equipment is installed on the wooden support and floor, it is difficult to avoid the interference of vibration, so the experiment is very difficult. According to himself, only one of 30 photos is often available, so the experiment has to be suspended. In the following period of time, many other physicists engaged in this work at the same time made important achievements.
Among these people, it is worth mentioning that in 1897, Michelson of the United States observed that the spectral line split into double lines in the magnetic field with an interferometer invented by himself. Later, Michelson invented the step grating with higher resolution (1899), and he used it to obtain more detailed results. T Preston, an Englishman, made an in-depth study of Zeeman effect. In his paper published in 1898, he described all kinds of magnetic splitting images in detail, and pointed out that Lorenz theory could not fully explain Zeeman effect. Later Preston's law was discovered. According to this law, the attribution of spectral lines can be determined.
German Runge and Pasin have also done a lot of experimental research on Zeeman effect. In 1902, they listed a lot of data and described some common laws between magnetic splits.
In 19 12, Pashen and Barker (E. E. A. Back) found that the abnormal Zeeman effect is triple split in extremely strong magnetic field, which is called Pashen-Barker effect. None of these phenomena can be explained theoretically, and it has been a mystery in physics for more than 20 years. As Pauli, the discoverer of the principle of incompatibility, later recalled: "On the one hand, this abnormal division has beautiful and simple laws, and it is fruitful; On the other hand, it's hard to understand ... I don't think I can start. "
192 1 year, Rand, a professor at the University of Dubingen, Germany, published a paper entitled "On Abnormal Zeeman Effect". He introduced a factor g to represent the energy change rate of atomic energy level under magnetic field, which is only related to the quantum number of energy level.
In 1925, Uhlenbeck and Goldschmidt put forward the concept of electron spin, "to explain Zeeman effect and complex spectral lines". In 1926, Heisenberg and Jordan introduced spin S, and made a correct calculation of anomalous Zeeman effect from the point of view of quantum mechanics. It can be seen that the study of Zeeman effect promotes the development of quantum theory and occupies an important position in the history of physics development.
Lorenz was born in Anand, the Netherlands, on July 8 1853. He is interested in physics and has mastered many foreign languages since he was a teenager. 1870, Lorenz was admitted to Leiden University to study mathematics, physics and astronomy. 1875 received a doctorate. 1877, Leiden university hired him as a professor of theoretical physics, when Lorenz was 23 years old. He taught at Leiden University for 35 years. During the period of1911-1927, Lorenz served as the chairman of Solvi Conference for many times. It enjoys a high reputation in the international physics field.
Lorenz's most important contribution to physics is the development of classical electronic theory. 1878, he published a paper on the interaction between light and matter, and distinguished ether from ordinary matter, thinking that ether is static and ubiquitous, and the molecules of ordinary matter all contain charged harmonic oscillators; On this basis, he derived the formula of molecular refractive index (Lorenz-Lorenz formula). 1892, he began to publish articles on electronic theory. He believes that all matter molecules contain electrons, and cathode ray particles are electrons. Electrons are small rigid spheres with mass, and they are completely transparent to ether. The interaction between ether and matter comes down to the interaction between ether and electrons in matter. On this basis, he put forward the famous Lorentz force formula in 1895. In addition, in l892, he studied the influence of the earth passing through the static ether. In order to describe the results of Michelson-Morey experiment, he independently put forward the hypothesis of length contraction, which holds that the length of an object moving in the ether direction is shortened. In 1895, he published an accurate length contraction formula, that is, in the direction of motion, the length contraction factor is. In l899, Lorenz discussed the transformation of coordinates and time between inertial systems, and came to the conclusion that electron mass is related to speed. 1904, he published the famous Lorentz transformation formula and the relationship between mass and speed, and pointed out that the speed of light is the limit of an object relative to the speed of ether.
In addition, Lorenz has profound attainments in many fields of classical physics, and has made contributions to thermodynamics, the theory of molecular motion of matter and the theory of gravity. Lorenz was respected by Einstein, Schrodinger and many other physicists. Einstein once said that he was deeply influenced by Lorenz in his life.