what is the theory for X-ray fluorescence?
Solution
In X-ray fluorescence, the sample is irradiated with X-ray radiation. In the process, the X-ray radiation can expel an electron from the atom. The electrons inside an atom occur in different orbits or shells (K, L, M, N....) outside the nucleus. Once an electron is knocked out of the atom, a vacancy or hole is created in one of the shells (say K-shell). The atom now is in an unstable excited state. To move back to the stable state, an electron is transferred from the higher shells, say the L-shell to the K-shell where vacancy was created. Since the energies of electrons increases with the increase in shells, hence the L-shell electron is supposed to have a higher energy than a K-shell electron. So when the L-shell electron jumps to the K-shell, excess energy is emitted as X-ray radiation which comprises of the X-ray photons and is seen in the form of a line in the spectrum. The emitted fluorescent radiation is evaluated by the detector.
The energy of the emitted X-ray radiation (or X-ray photons) depends upon the energy difference between the shell where a vacancy is created and the energy of the electrons that fills the vacancy. The energy levels are specific for a particualr atom, hence the emitted fluorescence radiation is a characteristic of an atom.
It is also possible that at a time, many electrons are expelled due to the high energy X-ray radiations, creating many voids, and to fill the voids, many electrons of different energies are transferred. In this case an atom will emit more than one energy radiations and in spectrum more than one lines will be obtained.The collection of the lines in the spectrum is a characteristic of a particular material. Hence by determining the energy or the wavelength of the emitted X-ray photon, the element can be determined.
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what is the theory for X-ray fluorescence-SolutionIn X-ray fluorescenc.docx
1. what is the theory for X-ray fluorescence?
Solution
In X-ray fluorescence, the sample is irradiated with X-ray radiation. In the process, the X-ray
radiation can expel an electron from the atom. The electrons inside an atom occur in different
orbits or shells (K, L, M, N....) outside the nucleus. Once an electron is knocked out of the atom,
a vacancy or hole is created in one of the shells (say K-shell). The atom now is in an unstable
excited state. To move back to the stable state, an electron is transferred from the higher shells,
say the L-shell to the K-shell where vacancy was created. Since the energies of electrons
increases with the increase in shells, hence the L-shell electron is supposed to have a higher
energy than a K-shell electron. So when the L-shell electron jumps to the K-shell, excess
energy is emitted as X-ray radiation which comprises of the X-ray photons and is seen in
the form of a line in the spectrum. The emitted fluorescent radiation is evaluated by the
detector.
The energy of the emitted X-ray radiation (or X-ray photons) depends upon the energy
difference between the shell where a vacancy is created and the energy of the electrons that
fills the vacancy. The energy levels are specific for a particualr atom, hence the emitted
fluorescence radiation is a characteristic of an atom.
It is also possible that at a time, many electrons are expelled due to the high energy X-ray
radiations, creating many voids, and to fill the voids, many electrons of different energies are
transferred. In this case an atom will emit more than one energy radiations and in spectrum
more than one lines will be obtained.The collection of the lines in the spectrum is a
characteristic of a particular material. Hence by determining the energy or the wavelength
of the emitted X-ray photon, the element can be determined.
