Becquerel history

The history of photoelectrochemical investigations at semiconductors apparently dates back to works of Becquerel (1839), who observed the occurrence of electric current under the illumination of metals, both with a pure... 

Edmond Becquerel (1820-1891) was the nineteenth-century scientist who studied the phosphorescence phenomenon most intensely. Continuing Stokes s research, he determined the excitation and emission spectra of diverse phosphors, determined the influence of temperature and other parameters, and measured the time between excitation and emission of phosphorescence and the duration time of this same phenomenon. For this purpose he constructed in 1858 the first phosphoroscope, with which he was capable of measuring lifetimes as short as 10-4 s. It was known that lifetimes considerably varied from one compound to the other, and he demonstrated in this sense that the phosphorescence of Iceland spar stayed visible for some seconds after irradiation, while that of the potassium platinum cyanide ended after 3.10 4 s. In 1861 Becquerel established an exponential law for the decay of phosphorescence, and postulated two different types of decay kinetics, i.e., exponential and hyperbolic, attributing them to monomolecular or bimolecular decay mechanisms. Becquerel criticized the use of the term fluorescence, a term introduced by Stokes, instead of employing the term phosphorescence, already assigned for this use [17, 19, 20], His son, Henri Becquerel (1852-1908), is assigned a special position in history because of his accidental discovery of radioactivity in 1896, when studying the luminescence of some uranium salts [17]. 

Mar. 8,1788, Chatillon-sur-Loing, France - Jan. 18,1878, Paris, France) French scientist, professor of physics at the Museum of Natural History (Paris), developed the Constant Current Cell , but received recognition for this cell only in France whereas elsewhere the almost identical cell is called -> Daniell cell (- Daniell). Becquerel helped in validating -> Faradays law, extensively studied metal deposition in particular in metallurgy and... 

The spectroscopic properties of ruby have been studied for over one hundred years starting with the work by Becquerel (1867), who excited ruby with sunlight. He claimed that the properties of this crystal were intrinsic, but later it was shown that the color as well as the luminescence of ruby are due to the Cr ion that plays the role of an optical center in the nonabsorbing AI2O3 host. Only much later these properties could be explained by considering the influence of the surroundings of the Cr center on its energy levels (crystal-field theory). For a summary of ruby history the reader is referred to ref. 1. 

The fact that atoms were not eternally stable became evident in the discovery of radioactivity by Becquerel, followed by the extensive investigations of nuclear transformations by Marie Curie, Rutherford, Soddy, and others. Atoms thus are not indivisible eternal building blocks, but rather entities having a life history from their birth from simpler atomic nuclei by nuclear fusion to their decay or fusion to form other atoms. Radioactive decay is the conversion in time of some atoms into others and thus makes clear the inadequacy of using the atoms now known as starting points for the construction of chemistry. 

Antoine-Henri Becquerel was bom the son of the physicist Alexandre-Edmond Becquerel, and the grandson of the physicist Antoine-Cesar Becquerel, and it is not surprising that he followed in their footsteps. It is also not surprising that his research interests centered around solar radiation and phosphorescence, as these are phenomena that his father had investigated. He entered the Ecole Polytechnique, in Paris, in 1872, which he left in 1874 and to which he subsequently returned. Becquerel received a doctorate degree from the Faculty of Sciences of Paris in 1888. In 1892, he was appointed professor of applied physics in the Department of Natural History at the Paris Museum, and in 1895, professor of physics at the Ecole Polytechnique. 

Nuclear medicine involves the injection of a radiopharmaceutical (radioactive drug) into a patient for either the diagnosis or treatment of disease. The history of nuclear medicine began with the discovery of radioactivity from uranium by the French physicist Antoine-Henri Becquerel in 1896, followed... 

The discovery and the history of radioactivity is closely connected to that of modern science. In 1896 Antoine Henri Becquerel observed and described the spontaneous emission of radiation by uranium and its compounds. Two years later, in 1898, the chemical research of Marie and Pierre Curie led to the discovery of polonium and radium. 

In view of the latter rem the phenomenon of stimulated emission has been mentioned, and certain laser materials will be mentioned later in this book. History illustrates this by the fact that ruby, investigated long ago by Becquerel, is the material on which the Krst solid state laser was based. In this chapter the return from the excited stale to the ground state was assumed to be radiative only. The next chapter considers nonradiative transitions. 

FIGURE 2.6 Marie Sklodowska Curie (1867-1934). When Marie Curie presented her doctoral thesis, it was described as the greatest single contribution of any doctoral thesis in the history of science. In 1903 Henri Becquerel, Maire Curie, and her husband, Pierre, were jointly awarded the Nobel Prize in Physics for their pioneering work on radioactivity (a term she introduced). In 1911 Marie Curie won a second Nobel Prize, this time in chemistry for her discovery of the elements polonium and radium. 

The radiochemlstry of lead has a history almost as long as the history of radiochemlstry Itself. In 1099j three years after the discovery of radioactivity by Becquerel and only a year after the discovery of radium and polonium by the Curies,... 

Henri Becquerel (1852-1908) grew up in Paris. His father Alexandre-Edmond Bec-querel was a professor of applied physics and had done research on solar radiation and on luminescence ). Henri studied at the Polytechnic from 1872. In 1892 he was appointed Professor of Applied Physics in the Department of Natural History at the Paris Museum. He became a professor at the Polytechnic in 1895. 

C. J. Giunta (transl.). Selected Classic Papersfrom the History of Chemistry, compiled from 1996. Henri Becquerel, On the invisible rays emitted by phosphorescent bodies. Read before the French Academy of Sciences, 2 March 1896, http //webserver.lemoyne.edU/faculty/g iunta/becquerel.html... 

The history of radiochemistry is in no small measure the story of two remarkable women, Marie and Irene Curie, and their husbands, Pierre Curie and Frederic Joliot. Marie Curie (1867-1934) was born Maria Sklodowska in Warsaw, Poland, then a part of the Russian empire. In 1891, she emigrated to Paris to study at the Sorbonne, where she met and married a French physicist, Pierre Curie (1859-1906). The Curies were associates of Flenri Becquerel (1852-1928), the man who discovered that uranium salts are radioactive. They showed that thorium, like uranium, is radioactive and that the amount of radiation emitted is directly proportional to the amount of uranium or thorium in the sample. 

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