HENRI BECQUEREL: BIOGRAPHY, DISCOVERIES, CONTRIBUTIONS - BIOGRAPHIES - 2024

Henri Becquerel (1852 - 1908) was a world-renowned physicist thanks to the discovery of spontaneous radioactivity in 1896. This earned him the Nobel Prize in Physics in 1903.

Becquerel also carried out research on phosphorescence, spectroscopy, and light absorption. Some of the most outstanding works that he published were Investigation on phosphorescence (1882-1897) and Discovery of the invisible radiation emitted by uranium (1896-1897).

Portrait of Henri Becquerel, physicist responsible for the discovery of radioactivity

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Henri Becquerel became an engineer and later acquired a doctorate of science. He followed in the footsteps of his father whom he replaced as a professor in the Department of Natural History at the Paris Museum.

Before the discovery of the phenomenon of radioactivity, he began his work studying the polarization of light through phosphorescence and the absorption of light through crystals.

It was at the end of the 19th century when he finally made his discovery by using uranium salts that he had inherited from his father's research.

Biography and studies

Family

Henri Becquerel (Paris, December 15, 1852 - Le Croisic, August 25, 1908) was a member of a family in which science was listed as a generational heritage. For example, the study of phosphorescence was one of the Becquerel's main approaches.

His grandfather, Antoine-César Becquerel, a member of the Royal Society, was the inventor of the electrolytic method used to extract various metals from mines. On the other hand, his father, Alexander Edmond Becquerel, worked as a professor of Applied Physics and focused on solar radiation and phosphorescence.

Studies

His first years of academic training were attended by the Lycée Louis-le-Grand, a renowned secondary school located in Paris and dating from the year 1563. Later he began his scientific training in 1872 at the École Polytechnique. He also studied engineering for three years, from 1874 to 1877 at the École des Ponts et Chaussées, a university-level institution dedicated to the sciences.

In 1888 he acquired a doctorate in science and began to be part of the French Academy of Sciences in 1889, which allowed his professional recognition and respect to increase.

Work experience

As an engineer, he was part of the Department of Bridges and Roads and was later appointed chief of engineers in 1894. Among his first experiences in academic teaching, he began as a teacher's assistant. At the Museum of Natural History he assisted his father in the chair of physics until he took his place after his death in 1892.

The nineteenth century was a time of great interest in the field of electricity, magnetism and energy, all within the physical sciences. The expansion that Becquerel gave to his father's work allowed him to become familiar with phosphorescent materials and uranium compounds, two important aspects for his later discovery of spontaneous radioactivity.

Personal life

Becquerel married Lucie Zoé Marie Jamin, daughter of a civil engineer, in 1878.

From this union the couple had a son, Jean Becquerel, who would follow the scientific path of his paternal family. He also held the post of professor at the Museum of Natural History of France, being the representative of the fourth generation of the family in charge of the chair of physics.

Henri Becquerel died at the young age of 56 in Le Croisic, Paris on August 25, 1908.

Discoveries and contributions

Prior to Henri Becquerel's encounter with radioactivity, Wilhelm Rôntgen, a German physicist, discovered electromagnetic radiation known as X-rays. This is where Becquerel set out to investigate the existence of any relationship between X-rays and natural fluorescence. It was in this process that he used the uranium salt compounds belonging to his father.

Becquerel considered the possibility that the X-rays were the result of fluorescence from the "Crookes tube" used by Rântong in his experiment. In this way he thought that X-rays could also be produced from other phosphorescent materials. Thus began the attempts to demonstrate his idea.

The encounter with radioactivity

In the first instance, becquerel used a photographic plate on which he placed fluorescent material wrapped with a dark material to prevent the entry of light. Then all this preparation was exposed to sunlight. His idea was to produce, using materials, X-rays that impressed the plate and that it remained veiled.

After testing a variety of materials, in 1896 he used uranium salts, which gave him the most important discovery of his career.

With two uranium salt crystals and a coin under each, Becquerel repeated the procedure, exposing the materials to the sun for a few hours. The result was the silhouette of the two coins on the photographic plate. In this way, he believed that these marks had been the product of X-rays emitted by the phosphorescence of uranium.

Later he repeated the experiment but this time he left the material exposed for several days because the climate did not allow a strong entry of sunlight. When revealing the result, he thought he would find a pair of very faint coin silhouettes, however, the opposite happened, when he perceived two much more marked shadows.

In this way he discovered that it was the prolonged contact with the uranium and not the sunlight that caused the harshness of the images.

The phenomenon itself shows that uranium salts are capable of converting gases into conductors when passing through them. Then it was found that the same happened with other types of uranium salts. In this way, the particular property of uranium atoms and therefore radioactivity is discovered.

Spontaneous radioactivity and other findings

It is known as spontaneous reactivity because unlike X-rays, these materials, such as uranium salts, do not need prior excitation to emit radiation, but are natural.

Subsequently, other radioactive substances began to be discovered, such as polonium, analyzed by the pair of scientists Pierre and Marie Curie.

Among Becquerel's other discoveries about reactivity is the measurement of the deflection of "beta particles", which are involved in radiation within electric and magnetic fields.

Recognitions

After his discoveries, Becquerel was integrated as a member of the French Academy of Sciences in 1888. He also appeared as a member in other societies such as the Royal Academy of Berlin and the Accademia dei Lincei located in Italy.

Among other things, he was also appointed Officer of the Legion of Honor in 1900, this being the highest decoration of order of merit awarded by the French government to civilians and soldiers.

The Nobel Prize in Physics was awarded to him in 1903 and was shared with Pierre and Marie Curie, for their discoveries associated with Becquerel's radiation studies.

Uses of radioactivity

Today there are various ways of harnessing radioactivity for the benefit of human life. Nuclear technology provides many advances that allow the use of radioactivity in various settings.

Radioactivity can be used in the area of ​​health through "nuclear medicine"

Image by Bokskapet from Pixabay

In medicine there are tools such as sterilization, scintigraphy and radiotherapy that function as forms of treatment or diagnosis, within what is known as nuclear medicine. In areas such as art, it allows the analysis of details in ancient works that help to corroborate the authenticity of a piece and in turn facilitate the restoration process.

Radioactivity is found naturally both inside and outside the planet (cosmic radiation). The natural radioactive materials found on Earth even allow us to analyze its age, since some radioactive atoms, such as radioisotopes, have existed since the formation of the planet.

Concepts related to Becquerel's works

To understand Becquerel's work a little more, it is necessary to know some concepts related to his studies.

Phosphorescence

It refers to the ability to emit light that a substance possesses when subjected to radiation. It also analyzes the persistence after the excitation method (radiation) is removed. Usually, materials capable of emitting phosphorescence contain zinc sulfide, fluorescein or strontium.

It is used in some pharmacological applications, many drugs such as aspirin, dopamine or morphine usually have phosphorescent properties in their components. Other compounds such as fluorescein, for example, are used in ophthalmological analyzes.

Radioactivity

Reactivity is known as a phenomenon that occurs spontaneously when the nuclei of unstable atoms or nuclides disintegrate into a more stable one. In the process of disintegration is where the emission of energy in the form of "ionizing radiation" originates. Ionizing radiation is divided into three types: alpha, beta, and gamma.

Photo plates

It is a plate whose surface is composed of silver salts which have the particularity of being sensitive to light. It is an antecedent of modern film and photography.

These plates were capable of generating images when in contact with light and for this reason they were used by Becquerel in his discovery.

He understood that the sunlight was not responsible for the result of the images reproduced on the photographic plate, but the radiation produced by the uranium salt crystals that was capable of affecting the photosensitive material.

References

1. 1. Badash L (2019). Henri Becquerel. Encyclopædia Britannica, inc. Recovered from britannica.com
   2. The Editors of Encyclopaedia Britannica (2019). Phosphorescence. Encyclopædia Britannica, inc. Recovered from britannica.com
   3. Brief History of Radioactivity (III). Virtual Museum of Science. Government of Spain. Recovered from museovirtual.csic.es
   4. Nobel Media AB (2019). Henri Becquerel. Biographical. The Nobel Prize. Recovered from nobelprize.org
   5. (2017) What is radioactivity ?. University of Las Palmas de Gran Canaria. Recovered from ulpgc.es
   6. Use of Radioactivity. University of Cordoba. Recovered from catedraenresauco.com
   7. What is radioactivity? Forum of the Spanish Nuclear Industry. Recovered from foronuclear.org
   8. Radioactivity in nature. Latin American Institute of Educational Communication. Recovered from Bibliotecadigital.ilce.edu.mx