under light excitation, PL spectra of some organic material changes with varyng the exitation wavelength, meanwhile, no changes in PL spectra of other material if we varie excitation wavelength. did some researchers give an explication of this difference on emission response.
Hi,
The response is in the band structure.
For example, the band structure of carbon permits a multi transition between valence and conduction bands. Then, varying the excitation is necessary to know all the electronic transitions. So, the excitation has an effect in the emission response in the carbon materiel.
Best regards.
Thanks a lot Mr Montassar for your response, so The change in PL response is du to existence of multi electronic state between valence and conduction bands.
best regards
If your compound has multiple fluorophores (specially if it is donor-acceptor type molecule) then there are chances existence of multiple excited states hence changing PL with change in excitation wavelength. Another possible reason is the red edge effect. It is environment dependent and usually favourable in polar viscous/slightly viscous solvents due to differently solvated fluorophore in the medium.
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