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The Bohr model of the hydrogen atom (Z = 1) or a hydrogen-like ion (Z > 1), where the negatively charged electron confined to an atomic shell encircles a small, positively charged atomic nucleus and where an electron jumps between orbits, is accompanied by an emitted or absorbed amount of electromagnetic energy (hν). [1]
The first person to correctly predict the phenomenon of spontaneous emission was Albert Einstein in a series of papers starting in 1916, culminating in what is now called the Einstein A Coefficient. [1] [2] Einstein's quantum theory of radiation anticipated ideas later expressed in quantum electrodynamics and quantum optics by several decades. [3]
The theory would have correctly explained the Zeeman effect, except for the issue of electron spin. Sommerfeld's model was much closer to the modern quantum mechanical picture than Bohr's. In the 1950s Joseph Keller updated Bohr–Sommerfeld quantization using Einstein's interpretation of 1917, [6] now known as Einstein–Brillouin–Keller method.
A spectrum of many such photons will show an emission spike at the wavelength associated with these photons. An absorption line is formed when an atom or molecule makes a transition from a lower, E 1, to a higher discrete energy state, E 2, with a photon being absorbed in the process. These absorbed photons generally come from background ...
Photons are massless particles of definite energy, definite momentum, and definite spin. To explain the photoelectric effect , Albert Einstein assumed heuristically in 1905 that an electromagnetic field consists of particles of energy of amount hν , where h is the Planck constant and ν is the wave frequency .
In 1905, Albert Einstein published a paper advancing the hypothesis that light energy is carried in discrete quantized packets to explain experimental data from the photoelectric effect. Einstein theorized that the energy in each quantum of light was equal to the frequency of light multiplied by a constant, later called the Planck constant. A ...
In 1918, Einstein developed a general theory of the process by which atoms emit and absorb electromagnetic radiation (the Einstein coefficients), which is the basis of lasers (light amplification by stimulated emission of radiation) and shaped the development of modern quantum electrodynamics, the best-validated physical theory at present.
Einstein was the first physicist to say that Max Planck's discovery of the energy quanta would require a rewriting of the laws of physics.To support his point, in 1905 Einstein proposed that light sometimes acts as a particle which he called a light quantum (see photon and wave–particle duality).