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Absorption spectrum and
Emission spectrum
These two phenomena are the
evidences for the resonant columns in atoms. When a
cooled gas is placed in the path of a continuous
spectrum of light, dark absorption lines will appear in
the resulting spectrum. Similarly, if we observe the gas
in oblique angle, emission lines will be visible against
a dark background. When a photon falls on an electron
and the resonant frequency of the shell (electron shell
or transitory shell) in which the electron presently
exist matches with the frequency of the photon, the
photon will be efficiently absorbed by the atom. In the
resultant spectrum, the absorbed photons will not be
present. This is the reason for the absorption line.
When a shell's electron absorbs a photon, the shell
oscillates with the frequency of the photon. This
oscillation of the shell causes its electron to create a
photon in the same frequency of the incident photon,
i.e. emission line is developed by reflected photons.
Zeeman Effect, Paschen-Back effect &
Stark effect
The electron configuration in a multi electron atom
is determined by three factors. a) Attraction from the
nucleus b) repulsion between electrons and c) buoyant
force exerted by space matter (see
structure of atom). When an atom is situated in a
strong- electric field or magnetic field, its electron
configuration is shifted from its normal state i.e.
because of the influence of the external field, some
electrons in the atom (mostly outer electrons) are
shifted from their original shells. When such an atom is
excited, the atom can emit different spectrum of
radiations compared to its original spectrum lines. This
effect is a direct indication for the strength of the
field i.e. when a weak field affects outer electrons
only, a strong field can influence both the inner and
outer electrons alike. Lighter elements can demonstrate
the effect in a weaker field comparatively than heavy
elements because the binding force on the electrons in a
lighter element is much less than that of heavy
elements.
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