Excitation and ionisation of atoms - Structure of matter Flashcards
Explain the ground state and excited state of an electron.
The quantum state of a bound electron with a minimum energy is called the ground state.
The states with higher energies are called excited states.
The excited state is reached by absorption of energy.
Electron can absord only such energy, which corresponds to the difference between the gorund level and some of excited energy levels.
One of the possibilities how an electron can gain the energy necessary for the transition into a higher eneryg level is absorption of photon.
Explain how an electron can gain the energy necessary for the transition into a higher energy lecel by absoption of a photon.
One of the possibilities how an electron can gain the energy necessary for the transition into a higher energy level is absorption of photon.
This absorption and quantum transition may take place only under the following conditions:
Bound electron can absorb only such photon whose energy, hf, equals the energy difference between the initial and final state (with higher energy).
Electron oes not exist in excited state for a long time but transits (deexcites) spontaneously to a lower energy state.
it can emit a photon whose energy equals the energy difference between the initial and final state (lower energy).
Spontaneous deexcitation (flurescence) appears ina short time interval (10-5 - 10-7 seconds).
The excitation energy is emitted in the form of one or more photons.
During deexcitation, the electron can reach such energy level from which the transition into the ground state is not allowed.
Therefore the electron remains in this metastable state for a substantially longer time and emits radiation later.
In such situation we speak about photophorescence.
What may follow the dexcitation state?
The deexcitiation may be followed by the emission of radiation.
Radiation transitions of electrons from higher into lower energy levels result in the luminescence.
