Corpuscular nature of light

The photoelectric effect is not only important as experimental evidence for the corpuscular nature of light but also finds applications in light detectors, and it is a fundamental process in photoelectrochemistry. 

Bohr had calculated the most accurately known experimental constant in physics by a method which was, to use a mild description, simply an outrage The corpuscular nature of light had come to stay it could no longer be ignored. No evangelist ever made so many converts in so short a time as did Bohr. 

One of the w atershed events in the development of physics and chemistry was the appearance of Einstein s landmark paper explaining the photoelectric effect, establishing the corpuscular nature of light, and leading to the modern view of the wave-particle duality of the microscopic realm. 

The nature of light seemed no longer to be simple. Light was a wave motion, but with Planck s work it acquired a corpuscular aspect. The light wave contains energy in elementary discrete units, quanta. 

In the late nineteenth century, a whole set of experiments progressively lead to the conclusion that classical physics, namely, Newtonian mechanics, thermodynamics, and nascent electromagnetism, were unable to explain empirical evidence gathered by experimentalists. Scientists of that time were unable to conciliate two apparent contradictory aspects exhibited by radiation and matter. Some experiments demonstrated that light behaved like a wave, while others showed a rather corpuscular nature. On the other hand, electrons, protons, and the other massive particles would manifest wave-like properties in certain experimental conditions. 

Louis Victor de Broglie (1892-) extended the dual character of light (wave and corpuscular) to matter. In 1924 he proposed that an electron in motion (as in a Bohr orbit) had a wave associated with it. C. J. Davisson, L. H. Germer, and G. P. Thomson found experimental evidence for this wave nature of particles in 1927 (Holum 1969, p. 37). 

The Erench physicist Louis de Broglie proposed in 1924 that not only light but all matter has a dual nature and possesses both wave and corpuscular properties. He reasoned that there should be symmetry in nature If a radiant corpuscle—-that is, a photon—has a frequency and a wavelength and therefore has wave properties, why should not a material particle also have wave properties (p. 429, original italics). .. When de Broglie first published his wave theory of matter, there was no experimental evidence to support his bold hypothesis. Within three years, however, two different experiments had been performed that demonstrated the diffraction of a beam of electrons. Clinton J. Davisson, assisted by L. H. Germer,. .. observed the diffraction of electrons when a beam of electrons was directed at a nickel crystal (Segal 1989, p. 431, underlined added). 

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