Antoine Henri Becquerel Biography (1852-1908)


The discovery of radioactivity has been called the most dramatic scientific breakthrough of our time. From the initial experiments came an understanding of the inner workings of the atom and the establishment of a new science, nuclear physics. Though many were to follow him, Henri Becquerel was the first toexperiment with radioactivity. Quite by accident, he observed the mysteriousenergy emitted by uranium, and his research sparked a new wave of scientifictheory.

That Becquerel became a scientist was of no surprise to his family--both hisfather and grandfather before him had been physicists. Becquerel's father hadspecialized in the study of fluorescence, and Henri began his own research in this field while attending college. He received his engineering degree in 1877 from the École des Ponts et Chaussees, after which he entered theAdministration of Bridges and Highways. During this time, his wife of four years died shortly after bearing him a son, Jean. Still concentrating on optics, Becquerel pursued his doctorate at the Faculty of Sciences of Paris. He delivered his dissertation in 1888 and was soon elected to the Academy of Sciences. Content to teach at the École Polytechnique, he ceased his experimentation, at least temporarily.

His father Edmond died in 1891, and the following year he was appointed to his father's chairs in the physics departments of the Conservatoire National des Arts et Métiers and the Museum of Natural History, all while continuing to lecture and serve at the Administration of Highways and Bridges. In 1895 he accepted an unprecedented third chair, this time at the École Polytechnique, and at age forty-three he had become one of the most powerful scientists in France, all without offering a major contribution to science. That, however, would soon change.

In the early days of 1896, Becquerel became one of the many scientists fascinated by Wilhelm Röntgen's discovery of x-rays. Wondering if these "penetrating rays" were related to the luminescence he had studied for years, he experimented with a sample of potassium uranyl sulfate crystal and a photographic plate. Exposing the sample to sunlight (to trigger the luminescent emission), he placed the crystal in a darkroom next to the photographic plate. Though the plate showed developed streaks, indicating the presence of penetratingrays, he noticed the effect whether the crystal had been exposed to light ornot. This eliminated the possibility of a luminescent connection, and Becquerel realized he had discovered a new type of penetrating ray. Further researchshowed that only crystals that contained uranium would develop the plate, and that a disk of pure uranium metal produced penetrating rays nearly four times as intense as his original sample.

Becquerel presented his findings to the world in May of 1896, labeling thesenew emissions Becquerel rays. Soon, Pierre Curie and Marie Curie, colleaguesof Becquerel, found that thorium also emitted Becquerel rays, and they laterdiscovered why: the presence of one of two new radioactive (a word coined by Marie Curie) elements, polonium and radium. Becquerel continued his own research, isolating electrons in radiation in 1900 and noting the first evidence of radioactive transformation in 1902.

From this point, the Curies took the leading role in radiation research. Becquerel became their liaison to the scientific world, presenting papers documenting their progress to the Academy of Sciences. For his discovery of radioactivity, Becquerel shared the 1903 Nobel Prize for Physics with the Curies. Hewas awarded numerous accolades and served as officer of many scientific organizations before his death in 1908.

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