Antoine-Henri Becquerel
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Antoine Henri Becquerel (; 15 December 1852 – 25 August 1908) was a French
engineer Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considering the limit ...
,
physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...
, Nobel laureate, and the first person to discover evidence of radioactivity. For work in this field he, along with Marie Skłodowska-Curie and
Pierre Curie Pierre Curie ( , ; 15 May 1859 – 19 April 1906) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity, and radioactivity. In 1903, he received the Nobel Prize in Physics with his wife, Marie Curie, and Henri Becq ...
, received the 1903
Nobel Prize in Physics ) , image = Nobel Prize.png , alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...
. The
SI unit The International System of Units, known by the international abbreviation SI in all languages and sometimes pleonastically as the SI system, is the modern form of the metric system and the world's most widely used system of measurement. ...
for radioactivity, the
becquerel The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. For applications relatin ...
(Bq), is named after him.


Biography


Early life

Becquerel was born in Paris, France, into a wealthy family which produced four generations of physicists: Becquerel's grandfather (
Antoine César Becquerel Antoine César Becquerel (7 March 178818 January 1878) was a French scientist and a pioneer in the study of electric and luminescent phenomena. Life He was born at Châtillon-sur-Loing (today Châtillon-Coligny). After passing through the École ...
), father ( Alexandre-Edmond Becquerel), and son ( Jean Becquerel). Henri started off his education by attending the
Lycée Louis-le-Grand The Lycée Louis-le-Grand (), also referred to simply as Louis-le-Grand or by its acronym LLG, is a public Lycée (French secondary school, also known as sixth form college) located on rue Saint-Jacques in central Paris. It was founded in the ...
school, a prep school in Paris. He studied engineering at the
École Polytechnique École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...
and the
École des Ponts et Chaussées École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...
. In 1874, Henri married Lucie Zoé Marie Jamin, who would die while giving birth to their son, Jean. In 1890 he married Louise Désirée Lorieux.


Career

In Becquerel's early career, he became the third in his family to occupy the physics chair at the
Muséum National d'Histoire Naturelle The French National Museum of Natural History, known in French as the ' (abbreviation MNHN), is the national natural history museum of France and a ' of higher education part of Sorbonne Universities. The main museum, with four galleries, is loc ...
in 1892. Later on in 1894, Becquerel became chief engineer in the Department of Bridges and Highways before he started with his early experiments. Becquerel's earliest works centered on the subject of his doctoral thesis: the plane polarization of light, with the phenomenon of
phosphorescence Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluo ...
and absorption of light by crystals.Henri Becquerel – Biographical
Nobelprize.org.
Early in his career, Becquerel also studied the
Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun. The magnetic ...
s. Becquerel's discovery of spontaneous radioactivity is a famous example of serendipity, of how chance favors the prepared mind. Becquerel had long been interested in
phosphorescence Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluo ...
, the emission of light of one color following a body's exposure to light of another color. In early 1896, there was a wave of excitement following
Wilhelm Conrad Röntgen Wilhelm may refer to: People and fictional characters * William Charles John Pitcher, costume designer known professionally as "Wilhelm" * Wilhelm (name), a list of people and fictional characters with the given name or surname Other uses * Mount ...
's discovery of
X-rays An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10  picometers to 10 nanometers, corresponding to frequencies in the range 30&nbs ...
on 5 January. During the experiment, Röntgen "found that the
Crookes tube A Crookes tube (also Crookes–Hittorf tube) is an early experimental electrical discharge tube, with partial vacuum, invented by English physicist William Crookes and others around 1869-1875, in which cathode rays, streams of electrons, were ...
s he had been using to study cathode rays emitted a new kind of invisible ray that was capable of penetrating through black paper". Learning of Röntgen's discovery from earlier that year during a meeting of the French Academy of Sciences caused Becquerel to be interested, and soon "began looking for a connection between the
phosphorescence Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluo ...
he had already been investigating and the newly discovered x-rays" of Röntgen, and thought that phosphorescent materials, such as some
uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
salts, might emit penetrating X-ray-like radiation when illuminated by bright sunlight. By May 1896, after other experiments involving non-phosphorescent uranium salts, he arrived at the correct explanation, namely that the penetrating radiation came from the uranium itself, without any need for excitation by an external energy source. There followed a period of intense research into radioactivity, including the determination that the element
thorium Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high ...
is also radioactive and the discovery of additional radioactive elements
polonium Polonium is a chemical element with the symbol Po and atomic number 84. Polonium is a chalcogen. A rare and highly radioactive metal with no stable isotopes, polonium is chemically similar to selenium and tellurium, though its metallic character ...
and
radium Radium is a chemical element with the symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (rathe ...
by Marie Skłodowska-Curie and her husband
Pierre Curie Pierre Curie ( , ; 15 May 1859 – 19 April 1906) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity, and radioactivity. In 1903, he received the Nobel Prize in Physics with his wife, Marie Curie, and Henri Becq ...
. The intensive research of radioactivity led to Becquerel publishing seven papers on the subject in 1896. Becquerel's other experiments allowed him to research more into radioactivity and figure out different aspects of the magnetic field when radiation is introduced into the magnetic field. "When different radioactive substances were put in the magnetic field, they deflected in different directions or not at all, showing that there were three classes of radioactivity: negative, positive, and electrically neutral." As often happens in science, radioactivity came close to being discovered nearly four decades earlier in 1857, when Abel Niépce de Saint-Victor, who was investigating photography under Michel Eugène Chevreul, observed that uranium salts emitted radiation that could darken photographic emulsions. By 1861, Niepce de Saint-Victor realized that uranium salts produce "a radiation that is invisible to our eyes". Niepce de Saint-Victor knew Edmond Becquerel, Henri Becquerel's father. In 1868, Edmond Becquerel published a book, ''La lumière: ses causes et ses effets'' (Light: Its causes and its effects). On page 50 of volume 2, Edmond noted that Niepce de Saint-Victor had observed that some objects that had been exposed to sunlight could expose photographic plates even in the dark. Niepce further noted that on the one hand, the effect was diminished if an obstruction were placed between a photographic plate and the object that had been exposed to the sun, but " … ''d'un autre côté, l'augmentation d'effet quand la surface insolée est couverte de substances facilement altérables à la lumière, comme le nitrate d'urane'' … " ( ... on the other hand, the increase in the effect when the surface exposed to the sun is covered with substances that are easily altered by light, such as uranium nitrate ... ).Edmond Becquerel, ''La lumière: ses causes et ses effets'', vol. 2 (Paris, France: F. Didot, 1868)
page 50


Experiments

Describing them to the French Academy of Sciences on 27 February 1896, he said:
One wraps a Lumière photographic plate with a bromide emulsion in two sheets of very thick black paper, such that the plate does not become clouded upon being exposed to the sun for a day. One places on the sheet of paper, on the outside, a slab of the phosphorescent substance, and one exposes the whole to the sun for several hours. When one then develops the photographic plate, one recognizes that the silhouette of the phosphorescent substance appears in black on the negative. If one places between the phosphorescent substance and the paper a piece of money or a metal screen pierced with a cut-out design, one sees the image of these objects appear on the negative ... One must conclude from these experiments that the phosphorescent substance in question emits rays which pass through the opaque paper and reduce silver salts.
But further experiments led him to doubt and then abandon this hypothesis. On 2 March 1896 he reported:
I will insist particularly upon the following fact, which seems to me quite important and beyond the phenomena which one could expect to observe: The same crystalline crusts f potassium uranyl sulfate arranged the same way with respect to the photographic plates, in the same conditions and through the same screens, but sheltered from the excitation of incident rays and kept in darkness, still produce the same photographic images. Here is how I was led to make this observation: among the preceding experiments, some had been prepared on Wednesday the 26th and Thursday the 27th of February, and since the sun was out only intermittently on these days, I kept the apparatuses prepared and returned the cases to the darkness of a bureau drawer, leaving in place the crusts of the uranium salt. Since the sun did not come out in the following days, I developed the photographic plates on the 1st of March, expecting to find the images very weak. Instead the silhouettes appeared with great intensity ... One hypothesis which presents itself to the mind naturally enough would be to suppose that these rays, whose effects have a great similarity to the effects produced by the rays studied by M. Lenard and M. Röntgen, are invisible rays emitted by phosphorescence and persisting infinitely longer than the duration of the luminous rays emitted by these bodies. However, the present experiments, without being contrary to this hypothesis, do not warrant this conclusion. I hope that the experiments which I am pursuing at the moment will be able to bring some clarification to this new class of phenomena.


Late career

Later in his life in 1900, Becquerel measured the properties of
Beta Particles A beta particle, also called beta ray or beta radiation (symbol β), is a high-energy, high-speed electron or positron emitted by the radioactive decay of an atomic nucleus during the process of beta decay. There are two forms of beta decay, β ...
, and he realized that they had the same measurements as high speed electrons leaving the nucleus. In 1901 Becquerel made the discovery that radioactivity could be used for medicine. Henri made this discovery when he left a piece of radium in his vest pocket and noticed that he had been burnt by it. This discovery led to the development of radiotherapy which is now used to treat cancer. Becquerel did not survive much longer after his discovery of radioactivity and died on 25 August 1908, at the age of 55, in
Le Croisic Le Croisic (; br, Ar Groazig; french: label= Gallo, Le Croèzic) is a commune in the Loire-Atlantique department, western France. It is part of the urban area of Saint-Nazaire. History The United States Navy established a naval air station o ...
, France. His death was from unknown causes, but was reported that "he had developed serious burns on his skin, likely from the handling of radioactive materials."


Honors and awards

In 1889, Becquerel became a member of the
Académie des Sciences The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at th ...
. In 1900, Becquerel won the Rumford Medal for his discovery of the radioactivity of uranium and he was made an Officer of the
Legion of Honour The National Order of the Legion of Honour (french: Ordre national de la Légion d'honneur), formerly the Royal Order of the Legion of Honour ('), is the highest French order of merit, both military and civil. Established in 1802 by Napoleon ...
. The Berlin-Brandenburg Academy of Sciences and Humanities awarded him the Helmholtz Medal in 1901. In 1902, he was elected as a member of the
American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...
. In 1903, Henri shared a
Nobel Prize in Physics ) , image = Nobel Prize.png , alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...
with
Pierre Curie Pierre Curie ( , ; 15 May 1859 – 19 April 1906) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity, and radioactivity. In 1903, he received the Nobel Prize in Physics with his wife, Marie Curie, and Henri Becq ...
and
Marie Curie Marie Salomea Skłodowska–Curie ( , , ; born Maria Salomea Skłodowska, ; 7 November 1867 – 4 July 1934) was a Polish and naturalized-French physicist and chemist who conducted pioneering research on radioactivity. She was the first ...
for the discovery of spontaneous radioactivity. In 1905, he was awarded the Barnard Medal by the U.S. National Academy of Sciences. In 1906, Henri was elected Vice Chairman of the academy, and in 1908, the year of his death, Becquerel was elected Permanent Secretary of the
Académie des Sciences The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at th ...
. During his lifetime, Becquerel was honored with membership into the Accademia dei Lincei and the Royal Academy of Berlin. Becquerel was elected a Foreign Member of the Royal Society (ForMemRS) in 1908. Becquerel has been honored with being the namesake of many different scientific discoveries. The SI unit for radioactivity, the
becquerel The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. For applications relatin ...
(Bq), is named after him. There is a crater named
Becquerel The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. For applications relatin ...
on the Moon and also a crater named
Becquerel The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. For applications relatin ...
on Mars. The uranium-based mineral
becquerelite Becquerelite is a uranium mineral with the chemical formula: Ca(UO2)6O4(OH)6·8(H2O). It is a secondary mineral which contains calcium and is a bright yellow colour. It has a Mohs hardness of about 2. It was named after the French physicist Antoi ...
was named after Henri. Minor planet 6914 Becquerel is named in his honor.


See also

*
Antoine César Becquerel Antoine César Becquerel (7 March 178818 January 1878) was a French scientist and a pioneer in the study of electric and luminescent phenomena. Life He was born at Châtillon-sur-Loing (today Châtillon-Coligny). After passing through the École ...
(his grandfather) * A. E. Becquerel (his father) * Jean Becquerel (his son) *
Becquerelite Becquerelite is a uranium mineral with the chemical formula: Ca(UO2)6O4(OH)6·8(H2O). It is a secondary mineral which contains calcium and is a bright yellow colour. It has a Mohs hardness of about 2. It was named after the French physicist Antoi ...
(mineral) *
Becquerel The becquerel (; symbol: Bq) is the unit of radioactivity in the International System of Units (SI). One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. For applications relatin ...
(SI unit)


References


External links

* * including the Nobel Lecture, December 11, 1903 ''On Radioactivity, a New Property of Matter''
Becquerel short biography
and the use of his name as a unit of measure in the SI
Annotated bibliography for Henri Becquerel from the Alsos Digital Library for Nuclear Issues

Henri Becquerel, SI-derived unit of radioactivity
* "Henri Becquerel: The Discovery of Radioactivity", Becquerel's 1896 articles online and analyzed on
BibNum
' lick 'à télécharger' for English version/small>. * * {{DEFAULTSORT:Becquerel, Antoine Henri 1852 births 1908 deaths 20th-century French physicists École Polytechnique alumni École des Ponts ParisTech alumni Corps des ponts Scientists from Paris Experimental physicists Nobel laureates in Physics Radioactivity French Nobel laureates French nuclear physicists Members of the French Academy of Sciences Foreign associates of the National Academy of Sciences Foreign Members of the Royal Society Nuclear history of France Members of the American Philosophical Society Presidents of the Société Française de Physique