Re: Quantum yield

Posted by Iain Johnson on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Rejected-posting-to-CONFOCALMICROSCOPY-LISTS-UMN-EDU-tp6866064p6877910.html

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Any of the conventional macroscopic methods of quantum yield determination
will be susceptible to large errors if implemented under a microscope as the
optical pathlength is so short.  Even in a cuvette, the precision of the
macroscopic methods is not so good (generally about +/- 5%).  Particularly
in the case of quantum dots, single molecule approaches make more sense and
are more physically informative than ensemble measurements:
http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&dopt=AbstractPlus&list_uids=16169907

Iain

Iain Johnson Consulting
Eugene, OR

On Fri, Oct 7, 2011 at 11:21 PM, Guy Cox <[hidden email]> wrote:

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> It's quantum dots, just to compound the problem.
>
>                                           Guy
>
> Optical Imaging Techniques in Cell Biology
> by Guy Cox    CRC Press / Taylor & Francis
>     http://www.guycox.com/optical.htm
> ______________________________________________
> Associate Professor Guy Cox, MA, DPhil(Oxon)
> Australian Centre for Microscopy & Microanalysis,
> Madsen Building F09, University of Sydney, NSW 2006
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> -----Original Message-----
> From: Confocal Microscopy List [mailto:[hidden email]]
> On Behalf Of MODEL, MICHAEL
> Sent: Saturday, 8 October 2011 12:19 AM
> To: [hidden email]
> Subject: Re: Quantum yield
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> Is the test sample a biological tissue or a solution of a chemical?
>
> -----Original Message-----
> From: Confocal Microscopy List [mailto:[hidden email]]
> On Behalf Of Guy Cox
> Sent: Thursday, October 06, 2011 9:44 PM
> To: [hidden email]
> Subject: Quantum yield
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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
>     http://www.guycox.com/optical.htm
> ______________________________________________
> Associate Professor Guy Cox, MA, DPhil(Oxon)
> Australian Centre for Microscopy & Microanalysis,
> Madsen Building F09, University of Sydney, NSW 2006
>
> Phone [phone]     Fax [phone]
>             Mobile [phone]
> ______________________________________________
>      http://www.guycox.net
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