popjinx Posted April 27, 2005 Share Posted April 27, 2005 why do some molecules fluoresce and others don't? Link to comment Share on other sites More sharing options...
swansont Posted April 28, 2005 Share Posted April 28, 2005 It depends on having states available to absorb energy, and suitible decay modes for releasing photons. If the molecule has many vibrational and rotational states avalable, it may not fluoresce. Link to comment Share on other sites More sharing options...
popjinx Posted April 28, 2005 Author Share Posted April 28, 2005 So, if the molecule has an option of vibrational relaxation, then it will do that instead.... simply because it is more favorable? Also, does conjugation have something to do wilth fluorescence? Link to comment Share on other sites More sharing options...
swansont Posted April 28, 2005 Share Posted April 28, 2005 It's going to depend on the strength of the coupling. It may be that there are no transitions in the visible, or that they are not strongly coupled. In those cases you wouldn't get fluorescence. I'm not sure what you mean by conjugation. Link to comment Share on other sites More sharing options...
popjinx Posted April 28, 2005 Author Share Posted April 28, 2005 By conjugation i mean structures with many pi bonds..... like aromatic rings. Link to comment Share on other sites More sharing options...
swansont Posted April 28, 2005 Share Posted April 28, 2005 By conjugation i mean structures with many pi bonds..... like aromatic rings. I'm not sure what effect that would have. It may give you a band structure, so that the fluorescence would have a wider spectrum, if they were involved in the optical transitions. But that's just speculation. Link to comment Share on other sites More sharing options...
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