The atom and the Bohr theory of its structure : $b an elementary presentationHolst, Helge
Science
The atom and the Bohr theory of its structure : $b an elementary presentation
Holst, Helge
Atomic theory
One might now object that we have here considered radiation due to a
transition between two successive stationary states, _e.g._, No.
100 and No. 99, or the like (a “single jump” we might call it). On the
other hand, for transitions between states whose numbers differ by 2,
3, 4 or more (as in a double jump, or a triple jump) the agreement
found above will wholly disappear, and doubt be cast on its value.
For in such cases of high orbit numbers the frequency of revolution
will remain approximately the same even for a difference of 2, 3, 4 or
more in orbit number; but the radiation frequency for a double jump
will be nearly twice that for a single jump, while that for a triple
jump will be nearly three times, etc. Accordingly, for approximately
the same revolutional frequency ω we shall have in these cases for
the radiation frequency very nearly ν₁ = ω, ν₂ = 2ω, ν₃ = 3ω, etc. We
must, however, remember that when the orbit in the stationary states is
not a circle, but an ellipse (as must in general be assumed to be the
case), the classical electrodynamics require that the electron emits
besides the “fundamental” radiation of frequency ν₁ = ω, the overtones
of frequencies ν₂ = 2ω, ν₃ = 3ω .... We then also here see the outward
similarity between the Bohr theory and the classical electrodynamics.
We may say that the radiation of frequency ν, produced by a single
jump, _corresponds_ to the fundamental harmonic component in the
motion of the electron, while the radiation of frequency ν₂, emitted by
a double jump, corresponds to the first overtone, etc.
The similarity is, however, only of a formal nature, since the
processes of radiation, according to the Bohr theory, are of
quite different nature than would be expected from the laws of
electrodynamics. In order to show how fundamental is the difference,
even where the similarity seems greatest, let us assume that we have
a mass of hydrogen with a very large number of atoms in orbits,
corresponding to very high numbers, and that the revolutional frequency
can practically be set equal to the same quantity ω. There may take
place transitions between orbits with the difference 1, 2, 3 ... in
number, and as the result of these different transitions we shall
find, by spectrum analysis, in the emitted radiation frequencies which
are practically ω, 2ω, 3ω, etc. According to the radiation theory of
electrodynamics we should also get these frequencies and the spectral
lines corresponding to them. It must, however, be assumed that they are
produced by the simultaneous emission from every individual radiating
atom of a fundamental and a series of overtones. According to the Bohr
theory, on the other hand, each individual radiating atom at a given
time emits only one definite line corresponding to a definite frequency
(monochromatic radiation).
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