![]() ![]() Schiff, Quantum Mechanics, Mc Graw-Hill, New York (1955).Ī. M Dirac, The Principles of Quantum Mechanics, Clarendon Press, Oxford (1958). Leighton and Sands, Addison-Wesley, Reading (1965).Ī. Sudarshan, Pauli and the Spin-Statistics Theorem, World Scientific, Singapore (1997). Kamefuchi, Quantum Field Theory and Parastatistics, Springer, Berlin (1982). Fowler, Monthly Notices of the Royal Astronomical Society 87, 114 (1926). Kaplan, The Pauli Exclusion Principle: Origin, Verifications and Applications, Wiley, Chichester, (2017). Pauli, Nobel Lecture, in Nobel Lectures, Physics, 1942-1962, Elsevier, Amsterdam, (1964). From this an important conclusion follows: we may not expect that in the future some unknown elementary particles can be discovered that are not fermions or bosons. Thus, the existence in our Nature of particles only in nondegenerate permutation states (symmetric and antisymmetric) is not accidental and so-called symmetrization postulate should not be considered as a postulate, since all other symmetry options for the total wave function may not be realized. However, the scenarios, in which arbitrary permutation symmetry (degenerate permutation states) is permitted, lead to contradictions with the concepts of particle identity and their independence. It is demonstrated that the proof in some textbooks on quantum mechanics that only symmetric and antisymmetric states can exist is wrong. On the other hand, according to PEP, the permutation symmetry of the total wave functions can be only of two types: symmetric or antisymmetric, both belong to one-dimensional representations of the permutation group, all other types of permutation symmetry are forbidden whereas the solution of the Schrödinger equation may have any permutation symmetry. As we will discuss, the physical reasons why SSC exists are still unknown. This is the so-called spin-statistics connection (SSC). On the one hand, it asserts that particles with half-integer spin (fermions) are described by antisymmetric wave functions, and particles with integer spin (bosons) are described by symmetric wave functions. PEP can be considered from two viewpoints. If you let book author know once you have cited this book, the brief information of your publication will appear on the “Times Cited” page.The modern state of the Pauli Exclusion Principle (PEP) is discussed. The book author ( Yougui Liao) welcomes your comments, suggestions, and corrections, please click here for submission. In x-ray absorption spectroscopy (XAS), for energies below an absorption edge, the x-rays penetrate rather easily without absorption because the Pauli exclusion principle prevents excitation. ![]() The left red circle is a zoom-in of the right red circle. ![]() Detailed illustration of electronic structure of silicon as a function of distance between atoms. Note that in crystal Si (with lattice spacing d 0), the core level electrons do not start yet to interact.įigure 3376. ![]() The upper band is empty and named as the conduction band. At the temperature of zero Kelvin, the lower band is completely filled with electrons and named as the valence band. A further reduction of the lattice spacing causes the 3s and 3p energy bands to merge into a single band having 8N available states, and then split again into two bands containing 4N states each. This splitting leads to 2N states in the 3s band and 6N states in the 3p band, where N is the number of Si atoms in the crystal. This leads to a splitting of the energy levels consistent with Pauli exclusion principle, and forming energy bands. As the distance between atoms is reduced to d 1, there is an overlap of electron wavefunctions across adjacent atoms. When atoms are far away from each other, the electrons in the out shell do not interact. An isolated Si atom contains 14 electrons, which occupy 1s, 2s, 2p, 3s and 3p orbital in pairs. The valence band electrons normally originate from the electrons in the incomplete outer shell of atoms, for instance, the valence band is formed for silicon (Si) crystals as shown in Figure 3376. This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers. ![]()
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