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CBSE - XI Science - Chemistry - Structure of Atom

what are flurocent or phosphorescent materials

Asked by NAMAN JAIN 11th August 2012, 7:55 PM
Answered by Expert


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.
Answered by Expert 11th August 2012, 9:23 PM

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