In the beginning of the
20th centuryNiels 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.
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)
where h is the Planck constant, p
is the momentum of the electron. The allowed orbits of an electron
are those which perimeters are equal the multiplied length of the
wave of the particle.
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
theX-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).
(1)
(2)