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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 .
This formula defines the photoelectric effect. Not every photon which encounters an atom or ion will photoionize it. The probability of photoionization is related to the photoionization cross-section, which depends on the energy of the photon and the target being considered. For photon energies below the ionization threshold, the ...
In explaining the photoelectric effect, the hypothesis that energy consists of discrete packets, as Einstein illustrates, can be directly applied to black bodies, as well. The idea of light quanta contradicts the wave theory of light that follows naturally from James Clerk Maxwell 's equations for electromagnetic behavior and, more generally ...
To explain the photoelectric effect, Einstein introduced the idea that light itself is made of discrete units of energy. In 1926, Gilbert N. Lewis popularized the term photon for these energy units. [3] [4] [5] Subsequently, many other experiments validated Einstein's approach. [6] [7] [8]
XPS physics - the photoelectric effect.. Because the energy of an X-ray with particular wavelength is known (for Al K α X-rays, E photon = 1486.7 eV), and because the emitted electrons' kinetic energies are measured, the electron binding energy of each of the emitted electrons can be determined by using the photoelectric effect equation,
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.
[3] [4] Einstein is best known by the general public for his mass–energy equivalence formula E = mc 2 (which has been dubbed "the world's most famous equation"). [5] He received the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect ", a pivotal step in ...
The photon's energy is converted to particle mass in accordance with Einstein's equation, E = mc 2; where E is energy, m is mass and c is the speed of light. The photon must have higher energy than the sum of the rest mass energies of an electron and positron (2 × 511 keV = 1.022 MeV, resulting in a photon wavelength of 1.2132 pm ) for the ...