Question
Sat August 11, 2012 By: Naman Jain
 

what are flurocent or phosphorescent materials

Expert Reply
Sat August 11, 2012
In fluorescence is caused by de-excitation of excited atoms immediately after the incident cause of the radiation . The excited energy levels in the fluorescent material are unstable and have a very short life time.

However the atoms in some substances have excited energy levels which have longer life times.(longer than 10^-8s). These are known as metastable states . It takes longer to come to the ground state. As a result the substance continues to emit light for a longer time after the removal of the source of the exciting radiation. These are known as Phosphorescent substances.
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