Posted by
Craig Brideau on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Rejected-posting-to-CONFOCALMICROSCOPY-LISTS-UMN-EDU-tp6866064p6868273.html
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If you knew the focal volume being illuminated, you could guess at how many
dye molecules were present based on concentration. Then based on input
power figure out the photon flux rate through the volume. The tricky part
would be figuring out what the chances are of any one dye molecule being
struck by a photon. If you had a photon counting detection system you could
then compare detected photons vs inputted photons. This would have to be
modified by the probability of a photon hitting a dye molecule in the first
place and the QE of your detector (so for every detected emitted photon
roughly how many do you fail to detected, and of course photon density in
the illuminated volume.
These are just my first thoughts. I'd have to give it more consideration,
especially regarding the likelihood of a photon hitting a dye molecule and
how that would modify the final value.
Craig
On Thu, Oct 6, 2011 at 7:43 PM, Guy Cox <
[hidden email]> wrote:
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> I got a rather left field enquiry today, as to whether there were
> calibration standards for quantum yield. It seems that the person wants
> to measure quantum yield under the microscope. My immediate response
> was that this is impossible. Quantum yield is easy enough to measure in
> a cuvette but would it be possible in a microscope? You could make a
> standard of a known concentration of fluorescein in a cell made by a
> spacer under the coverslip, but where do you go from there, if both
> quantum yield and extinction coefficient of the test sample are unknown?
>
> Any bright ideas?
>
> Guy
>
>
>
>
> Optical Imaging Techniques in Cell Biology
> by Guy Cox CRC Press / Taylor & Francis
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