Posted by
Steffen Dietzel on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Microscopy-used-equipment-tp4594144p4597701.html
At 07:51 19.02.2010, you wrote:
>Hi Christian,
>
>If you use the 633 laser, youll get the
>expected emission peak at around 695 nm which is
>largely photosystem II emission, then a flat
>tail up to 760 or so which is mostly PSI. There
>are many absorption and emission spectra around,
>though I suspect quite a few of these are for
>isolated pigments in a polar solvent. The
>emission spectra depend very strongly on the
>wavelength(s) of the excitation light, so there
>isnt really a standard emission
How does that fit to the theory of fluorescence?
The theory says that fluorescence occurs when an
electron is falling from the lowest energy level
of the excited state to (any) energy level of the
ground state, emitting a photon during the
process. I thought because of that, the
fluorescent spectrum wavelength is supposed to be
always the same, independant of the mode of excitation.
Did I miss something or is there a problem with the theory?
While I am on it: If the theory is correct, how
can excitation and emission spectra overlap
without breaking the law of conversation of
energy? (Example: If you would excite FITC with
510 nm, how could you obtain the part of the
emission spectrum below 510? I am not sure one
actually would get this part, but if not, this
would seem to argue against the theory of fluorescence.)
Steffen
-- ---------------------------------------------------
Steffen Dietzel, PD Dr. rer. nat
Ludwig-Maximilians-Universität München
Walter-Brendel-Zentrum für experimentelle Medizin (WBex)
Marchioninistr. 15, D-81377 München