1. Louis, 7 th duc de Broglie, Nobel Laureate.

2. Biography ● He was born in Dieppe(Siene), younger son of Victor, Duc de Broglie, and Pauline d'Armaillé. ● Louis studied at the Lyceé Janson de Sailly in Paris. He completed his secondary school education in 1909. ● In the first years of his life in university, he studied history and intended to be a humanist. At the age of 18 he graduated with an arts degree.

3. Biography ● Afterwards, he became interested in mathematical physics. ● During World War 1, he served in the station at the Eiffel Tower (wireless telegraphy section). ● During these years, he spent his spare time to think about technical problems. “ When in 1920 I resumed my studies... what attracted me... to theoretical physics was... the mystery in which the structure of matter and of radiation was becoming more and more enveloped as the strange concept of the quantum, introduced by Placnk in 1900 in his researches into black-body radiation, daily penetrated further into the whole of physics. “ ● ● In 1924, he introduced his theory of electron waves (Recherches sur la théorie des quanta - Research on Quantum Theory). This included the wave-particle duality theory of matter, based on the work of Einstein and Planck.wave-particle dualityEinsteinPlanck

4. Biography  He created the new field of physics, mécanique ondulatoire, - wave mechanics. He united physics of light and matter.  For this work, he won the 1929 Nobel Prize.  Between 1930 and 1950, Louis de Broglie's work has been chiefly devoted to the study of the various extensions of wave mechanics.  Since 1951, together with young colleagues, Louis de Broglie resumed the study of an the theory of the double solution to give a causal interpretation to wave mechanics in the classical terms of space and time.  Back again in this his former field of research, he has obtained a certain number of new and encouraging results which he has published in notes to Comptes Rendus de l'Académie des Sciences and in various expositions.

5. Biography   Louis de Broglie became a member of the Académie des sciences in 1933, and was the academy's perpetual secretary from 1942. On 12 October 1944, he was elected to the Académie française, replacing mathematician Émile PicardAcadémie des sciences19331942 12 October1944Académie françaiseÉmile Picard   He was also awarded the Henri Poincaré medal and the Albert I of Monaco prize.   Other honours which he received included the Kalinga Prize which was awarded to him by UNESCO in 1952 for his efforts towards the understanding of modern physics by the general public.   He never married.   Louis de Broglie died on March 19, 1987.

6. Contribution  The wave nature of electron.  De Broglie hypothesis: every moving particle or object had an associated wave.  Started a new field of physics: wave mechanics.  Most important publications: Recherches sur la théorie des quanta (Researches on the quantum theory) (1924), Ondes et mouvements (Waves and motions) (1926), La mécanique ondulatoire (Wave mechanics) (1928)…

7. Wave-particle duality  In physics, wave-particle duality holds that light and matter can exhibit properties of both waves and of particles. It is a central concept of quantum mechanics.  Through the work of Albert Einstein, Louis de Broglie and many others, it is now established that small objects, such as atoms, have both wave and particle nature, and that quantum mechanics provides the over-arching theory resolving this apparent paradox Albert EinsteinLouis de BroglieatomsparadoxAlbert EinsteinLouis de Broglieatomsparadox

8. History  In 19 th century, light was believed to be a wave because of its property: diffraction and interference.  By 20 th century, Albert Einstein analysed the photoelectric effect. He explained that light has both particle-like and wave-like properties.

9. History  In 1924 De Broglie hypothesis, predicts that every particles also behave as waves:  h is Planck's constant and p the momentum of the electron, giving the wavelength of any particle.

10. De Broglie Hypothesis

11. History  Later, 2 independent experiments showed the diffraction of electrons which had been thought to only have particle-like property.  At the University of Aberdeen George Paget Thomson passed a beam of electrons through a thin metal film and observed the predicted interference patterns.  At Bell Labs Clinton Joseph Davisson and Lester Halbert Germer guided their beam through a crystalline grid.

12. History  Acceleration of electron:  U is electric potential, m0 is the mass of electron and e is the elementary charge.

13. Nobel Stamp (1987)  The 1982 Nobel Stamps issue illustrates the theme nuclear physics and honours five winners of the Nobel Prize in Physics. They were rewarded for their work in developing a new atomic theory-- quantum mechanics. The Laureates are: NIELS BOHR, Denmark (1922), ERWIN SCHRöDINGER, Austria (1933), LOUIS DE BROGLIE, France (1929), PAUL DIRAC, England (1933) and WERNER HEISENBERG, Germany (1932). NIELS BOHRERWIN SCHRöDINGERLOUIS DE BROGLIEPAUL DIRAC WERNER HEISENBERGNIELS BOHRERWIN SCHRöDINGERLOUIS DE BROGLIEPAUL DIRAC WERNER HEISENBERG

14. Do you know that?   Louis, 7 th Duc de Broglie came from a noble family in France.   The family counts among its members three marshals of France, a Nobel Prize laureate, and several members of the Institut de France.marshals of France Nobel PrizeInstitut de France

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