Chemical Forums

Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: tetty on October 10, 2007, 10:33:46 AM

Title: luminescence spectrometry
Post by: tetty on October 10, 2007, 10:33:46 AM

hello all!
I want to learn what are the differences in atomic floresence spectrometry and molecular floresence spectrometry, these are look like similar.
thanks !

Title: Re: luminescence spectrometry
Post by: ARGOS++ on October 11, 2007, 09:48:41 AM

Dear Tetty,

I believe that you intermix two terms of spectroscopy for one moment.
The cause for that lies in the term “Luminescence”!
“Luminescence” in opposite to “Incandescence” defines a so called “Cold Radiation of Light”, and follows therefore other rules as the “Black Body Radiation” (=BBR)!
In the “Cold State” you will find very less only “Pure Atomic Compounds” for such analysis.
For “Luminescence” there are a lot of different Energy sources known to populate the excited state of the molecule.

So “Atomic Fluorescence” is ??“miss-“?? used as a “Luminescence”; it is in real a “Incandescence”, because it heats the atom or compound inside a flame/plasma till it emits Light by itself (BBR), and at that temperature almost all compounds/molecules are already destroyed anyway ( to only atoms?)!
As more kind of Fluorescences as you include as more complicate it will go, and as less consequent/clear the terms are differentiated, too.

Quintessence:   Don’t interchange “Luminescence” and “Fluorescence” in general, as you did!
 
Good Luck!
                    ARGOS⁺⁺