Chapter 19 (II)

Chapter 19 (II) - 19.3 Free Electron Model of Metals the...

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Unformatted text preview: 19.3 Free Electron Model of Metals the free electron gas model the outer valence electrons In the free electron gas model, the outer valence electrons of atoms move freely in a potential well. The free electrons occupy the lowest energy states up to the Fermi level E F , which is the chemical potential (T). Strictly speaking, E = (T). (T) Fermi level E F F However, from the above we know that at ordinary temperatures, (T) ~ (0)= , Potential well for free electrons in a metal F the Fermi energy. Thus, E F F . An associated physical quantity is the work function of the metal surface, , which is the energy required to remove an electron at E F from the metal surface, i.e., the minimum energy required to remove an electron from the surface. Einsteins Theory of the Photoelectric effect In 1905, Einstein proposed that EM radiation itself is composed of light quanta (photons) whose energy is h , where is the EM frequency. The light intensity I=nh , n is the photon number. The emission of electrons from the metal under light irradiation ccurs only if occurs only if h ....
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Chapter 19 (II) - 19.3 Free Electron Model of Metals the...

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