THE EXPERIMENTS CONFIRMING THE WAVE STRUCTURE OF
THE ELECTRON
In 1925 Clinton Davisson and C.H.
Kunsman (later also Laster Germer) begun to conduct the experiments
which confirmed the de
Broglie's theory. They shot the crystal of nickel with a beam
of electrons from the glowing cathode. That caused a secondary
emission of electrons from the crystal. The number of the electrons
sent in different directions was defined using the collector - a
metal plate which incidencing electrons. The collector could have
been moved around the crystal. By the accident the one of the
nickel plates oxidised. To remove nickelic peroxide the plate was
heated. After that the plate was used again in the experiment. But
the results occurred to be completely different than before. That
was because the method of cleaning the plate changed it in a big
monocrystal. The electrons were emit from such plate in all
directions but at some angles the emission was bigger. For the beam
of electrons of the energy of 54 MeV the angle of the increased
emission was equal about 500. The momentum of the
electrons is given by a formula:
(1)
where m0 is the rest mass of the electron, E is the
energy of the electron. The angles at which the diffraction
maximums occur can be calculated knowing the wave length and the
construction of the diffraction
grating. From the other hand the wave length can be calculated
knowing the angles of the maximums and the characteristic of the
grating. The wave length calculated by the scientists was equal
1,65*10-10 m. According to the de Broglie's wave theory the
wave length of the electron when the wave is of the energy of 54
MeV is equal 1,67*10-10 m. Conformity of the two values
confirmed the wave structure of the electron.
At the same time George Paget Thomson (1892-1975)
(J.J. Thomson's son)
conducted a different experiment and also proved the wave structure
of electrons. The thin (about 10-5 cm) gold foil was
bombarding by a beam of electrons of a high velocity (of the energy
of about 104 eV). The electrons went through the foil
but when they did diffraction occurred. Thomson observed the
diffraction rings on the screen behind the foil. The rings were the
proof for the wave structure of the electrons.
The two described above
experiments were the most important ones confiming the wave nature
of the electron. In 1937 Clinton Joseph Davisson and
George Paget Thomson received the Nobel
Prize.
But there were more such
experiments conducted.
For example the German scientist Rupp measured the
length of the electrons wave. He used the phenomena of the
diffraction of the beam of electrons on the optical diffraction grating.
Soon it was also proved
that the other particles are also of the wave nature.
In 1931
Johnson noticed the diffraction of the beams of hydrogen particles
scattered on crystals, and in 1938 Stern, Easterman, and
Frisch observed the
diffraction of the beam of helium particles on a crystal.
- Computer programm -
experiment simalation
