Deactivation
Under the deactivation is the process by which atoms or molecules of their excess energy proposed to the environment.
The excess energy can exist in a high reactivity on the chemical level and in an excited state on the physical level . Have a high reactivity z. B. those chemical elements whose outermost electron shell is not fully filled and which require little or no activation energy to trigger a reaction (“matchstick function”).
It is essential to deactivate chemical substances before they are disposed of by allowing them to react under controlled conditions. This prevents them from reacting in the waste containers in an uncontrolled manner. Examples are the deactivation of sodium in alcohol or that of hydrides in water .
An atom or molecule that is excited (activated) by some kind of energy supply has electrons at a higher energy level (to which an orbital is assigned) than their normal ground state . Various options can be considered for deactivation, one of which is radiative deactivation.
Deactivation by radiation
During the radiative deactivation , the excited electrons fall back into their original orbital. The energy difference is emitted in the form of a photon . The emitted radiation has a specific wavelength that can be in the spectrum visible to the human eye (approx. 390 to almost 800 nanometers ); We see these substances glow in different colors ( luminescence , fluorescence , phosphorescence ). The wavelength of the emitted radiation can also lie in spectral ranges that are not visible to us.
An important application of radiant deactivation is laser technology .
literature
- Peter W. Atkins : Short textbook physical chemistry , Wiley-VCH, ISBN 3527304339