In the beginning of the 20th century Niels Bohr created the theory which described the behavior of the electron circulating around the atomic nucleus. But it didn't explain the cause of such behavior. It didn't explain way electron can take only some define orbits - the stationery orbits. Many scientists worked over this problem.
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In 1925 Louis Victor de Broglie (1892-1987) suggested that there
is a wave connected with the moving electron. The length of that wave as he said is equal:
(1)
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Let's take a look on the de Broglie theory. It was known that for the photons the momentum is connected with the wave length by the formula (1). De Broglie noticed that the connection is also truth for the particles of matter. We can substitute the momentum with the expression m*v, where m is the mass of the particle, v is its velocity. So the expression for the wave length looks like shown below:
(2)
The formula shows that the particle of smaller velocity and the smaller mass is characterized by longer wave length. Let's imagine the two examples:
The baseball ball of the mass of 0,14 kg is through by a pitcher with the velocity of 40 m/s, after placing the data to the formula we get the wave length equal 1,2*10-34 m. It isn't much, actually even using the most modern technologies you wouldn't see it.
From the other hand the electron moving with the velocity of 40 m/s has the wave length equal 1,8*10-5 m. Such waves can be observed.
Not long after they showed that the electron could be connected with the wave Heisenberg and Schrodinger described the waves mathematically. Their formulas explain very well the observed experimental facts.
UUntil then the scientists imagined the electron as a very small ball of a defined radius. The scientists of the 20tieths of our century gave the description of the electron showing it being a wave and created a corpuscular-wave picture of the electron. So the electron appeared to be both the small ball and the wave. It doesn't behave as the thinks of the macro scale and the laws governing that thinks are not through when talking about electron.
According to the new theory the electron should behave like a wave do. So the electron should undergo interference and diffraction.
In 1925 Walther Erlasser noticed that if the electrons were connected with waves they should undergo diffraction, when reflected from a crystal - exactly as the X-rays did.
In 1925 Clinton Joseph Davisson (1881-1958) continued the researches on the electrons scattered on nickel. Working over it he has an accident in his laboratory. The bottle with liquid air exploded. The hot nickel which rapidly contacted air strongly oxidated. After such conversion exterior part of the plate compounded of the much bigger crystal than before. It occurred that the plate scattered the electrons in a completely different way than before. That accident induced series of Davisson researches on the electrons colliding monocrystals. He got interested with the Schrodinger works and using them he tried to explain the phenomena. After he made many calculation and conducted many experiments in the beginning of 1927 he noticed a strong beam surely caused by the diffraction of electrons.
At the same time George Paget Thomson (J.J. Thomson's son) also conducted experiments on the electrons scattering. He also received diffraction.
In 1937 they both received the Nobel Prize.
In the fall of the 20thies of our century the theory of wave-corpuscular structure of the electron was experimentally proofed after it was formulated only a few years before. The scientists discovered that the one of the basic components of atom is not so simple as they thought before. The electron characterized both with the features of a particle and a wave.
The features of the electron are being used in different departments of science (e.g. for construction of the electron microscope).
