[RASMB] laser delay difference between sample and water?

Frank Niesen Frank.Niesen at sgc.ox.ac.uk
Wed Nov 5 05:49:17 PST 2008


Hello everybody,

I wonder if you have experience with a phenomenon that I experienced on several occasions, using interference optics:

I adjust the laser delay for all cells while running blanks, i.e. filled with water. I do this at the high speed, when I record the blank scans for all cells. The reason is that I noticed that a longer laser delay is necessary at higher than at lower speed.
Then I remove the water from the cells and fill in my samples. I test those with a scan at 3000 rpm and when everything seems alright I start the experiment after equilibration.
However, I frequently see that at the high speed later on the signal in one of the cells has become too faint and the experiment needs to be repeated/re-started after mixing etc.

It seems wrong to me that it would be required to adjust the delay with the sample at high speed: Apart from the fact that one potentially loses valuable information there is the fact that it is not happening for all cells in general.

Many thanks in advance for any advice you might be able to give me.

Best regards,

Frank


Dr. Frank H. Niesen

Chemical Biology
Structural Genomics Consortium
University of Oxford
ORCRB, Roosevelt Drive
Oxford, OX3 7DQ
United Kingdom

frank.niesen at sgc.ox.ac.uk
skype ID: frankniesen 
phone +44 (0)1865 617578
fax      +44 (0)1865 617575
http://www.sgc.ox.ac.uk/ 





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