To address the first part of your discussion, chlorophyll emission
detected in our Meta system is always the same from different plants
and with different excitations, with a peak near 680.
Howard
On Feb 19, 2010, at 7:10 AM, Steffen Dietzel wrote:
> At 07:51 19.02.2010, you wrote:
>> Hi Christian,
>>
>> If you use the 633 laser, you’ll 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
>> isn’t 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