Wave nature of electron

When Davisson and Germer reported in 1927 that the elastic scattering of low-energy electrons from well ordered surfaces leads to diffraction spots similar to those observed in X-ray diffraction [2.238-2.240], this was the first experimental proof of the wave nature of electrons. A few years before, in 1923, De Broglie had postulated that electrons have a wavelength, given in A, of ... 

L. V. de Broglie (Paris) discovery of the wave nature of electrons. 

In LEED, electrons of well-defined (but variable) energy and direction of propagation diffract off a crystal surface. Usually only the elastically diffracted electrons are considered and we shall do so here as well. The electrons are scattered mainly by the individual atom cores of the surface and produce, because of the quantum-mechanical wave nature of electrons, wave interferences that depend strongly on the relative atomic positions of the surface under examination. 

The famous experiment proposed by Aharonov and Bohm [53,54] is schematically represented in Fig. 6. In such an experiment, a source emits an electron beam directed toward a wall in which two slits, located on each side of the beam axis, are located. A photographic plate (film) placed behind the slits records impacting electrons. After the emission of a large number of electrons by the source, the aforementioned film exhibits neat, clear, and dark fringes that are parallel to the slits. This result is interpreted as a manifestation of the wave nature of electrons. 

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Was this your answer Moving According tode Broglie, particles of matte1 behave like waves by virtue of their motion.The wave nature of electrons in atoms is pronounced because electrons move at speeds of about 2 million meters per second. 

The wave nature of electrons explains so many previously unexplained facts for the following reason. If waves are confined to a finite region of space, iliey form characteristic shapes and patterns that are specific to (lie nature of the confinement. [Figure 8 in the entiy on Chemical Elements shows waves in space confined to the neighborhood of a central point.] Only those and no other patterns can develop in this sort of confinement. But this is just the confinement that electrons suffer when they are confined around the atomic nucleus by electric attraction. The electron waves in atoms must assume some of these patterns. The simple patterns are lower than the more complex ones they are lower in energy. Indeed, the electrons in an atom assume the lowest possible patterns. 

It was only in 1927 from the experiments of Davisson and Germer and slightly later from those of G. P. Thomson that it was found that these electron beams exhibit exactly the same diffraction phenomena as those which Von Laue, Friedrich and Knipping had observed with X-rays in 1912. For X-rays this result was in agreement with the prevailing conception of the nature of these rays. With electrons, however, this wave character appeared to be completely in conflict with the ideas which had been supported for more than 50 years, nevertheless only three years before De Broglie had published his fundamental hypothesis on the wave nature of electrons in his thesis (1924). 

An important feature of the band system is that electrons are delocalised or spread over the lattice. Some delocalisation is naturally expected when an atomic orbital of any atom overlaps appreciably with those of more than one of its neighbours, but delocalisation reaches an extreme form in the case of a regular, 3-dimensional lattice. We can understand this best if we choose to think of the wave nature of electrons, and from that point of view we can formulate band theory as follows. 

I ve been using marbles and atom-size insects as an analogy for electrons, but I don t want to leave you with the misconception that electrons can only be thought of as solid objects. In the introduction to this book and in the first chemistry book, I discussed how we can think of electrons (and all particles, for that matter) as collections of waves. It is this wave nature of electrons that is the basis for quantum mechanics, which is the math we use to come up with the uncertainty principle. So, while it is often convenient to consider electrons to be tiny, solid objects, you should always be aware of the model of electrons as waves. 

Although they are true believers in the wave nature of electrons, the physicists at the IBM Al-maden Research Center in San Jose, California, were genuinely surprised when their scanning tunneling microscope (STM) produced this image of the copper surface. We looked at the surface with all these waves and thought, Is our machine bro-... 

Other experiments also supported the wave nature of electrons. Like light waves, electrons can change direction through diffraction. Diffraction refers to the bending of a wave as the wave passes by the edge of an object, such as a crystal. Experiments also showed that electron beams, like waves, can interfere with each other. 

The molecular orbital (MO) concept of chemical bonding is based on these fundamental assumptions. As the name implies, MOs are similar in concept to atomic orbitals in fact, molecular orbitals are derived from atomic orbitals. Both types of orbitals are based on the wave nature of electrons therefore, all five characteristics listed previously for atomic orbitals also apply to molecular orbitals. 

Both types of orbitals describe the wave nature of electrons in some cases, a single orbital may have positive and negative portions (lobes) representing positive and negative values of the corresponding wave functions (like peaks and valleys of waves on an ocean). For example, this is the case for 7T molecular orbitals and p atomic orbitals. 

Owing to the wave nature of electrons, the ionic radius of an element is not an easily measured quantity. The numbers which appear in tables are essentially empirical values, such that when the ionic radii of an anion and cation are added together the result is the distance apart the ions would be if measured in an ionic compound. Evidence for this idea of fixed size of ions is derived from interionic distances measured by X-ray diffraction methods (Table 1.5). 

The hrst half of this chapter reviews the Lewis model of chemical bonding and the procedures for writing structural formulas of chemical compounds, especially organic ones. The second half discusses bonding in terms of the wave nature of electrons and concludes with its application to compounds that contain carbon-carbon single bonds, double bonds, and triple bonds. 

The Wave Nature of Electrons and the Particle Nature of Photons... 

FIGURE 340. STM image of the quantum corral consisting of 48 iron atoms placed one at a time. The image shows the particle-wave nature of electrons (P. Avouris, Accounts of Chemical Research, 28 95, 1995 courtesy American Chemical Society the author thanks Dr. Phaedon Avouris, IBM Research Division, for this figure). 

The solution, proposed by Einstein, was that the discrete energy units, identified by Planck, correspond to quanta of light, called photons, which interact with electrons in the metal surface during direct collision. This dual wave/particle nature of light inspired de Broglie to postulate a similar behaviour for electrons. Experimental observation of electron diffraction confirmed the wave nature of electrons and firmly estabUshed the dual character of all quantum objects as mysterious reality. As the logical pictme of an entity, which is wave as well as particle, is hard to swallow, it has become fashionable to avoid all physical models of quantum events it is considered poor taste to contaminate the quantmn world with classical concepts. This noble idea of the so-called Copenhagen interpretation of quantmn theory has resulted in a probabilistic computational model that, not only defies, but denies comprehension. 

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