[RASMB] XL-I laser wavelength, magnitude versus pixels per fringe and mag netic field(s)

[Karel Planken]

Dear RASMB'er,

 

Here are a few questions regarding our XL-I.

 

Question 1:

On the laser tube it reads for the wavelength of the laser 675 nm. Since we
have a new computer the reported wavelength for the recorded scans is 655 nm
(before it was 660 nm!?). Why are these different and how can we change or
set this back to 675 nm?

 

Question 2:

If I set up the laser (delay and duration) and check the magnitude versus
pixels per fringe (see attachment) I often get a pretty smooth curve but
with a kink half way, just before the maximum. Is it very important to
obtain a completely smooth curve? Adjusting the laser delay, the kink can be
minimized but usually doesn't disappear completely.

 

Question 3:

The rotor is driven by three coils underneath the rotor chamber that produce
a (alternating?) magnetic field(s). Since I measured the sedimentation
velocity of magnetic particles I would like to raise the following question:
can somebody provide me information on how strong this magnetic field is (or
better: how strong is the magnetic field that the sample sector of a
standard d.s. centerpiece experiences?) and how the magnetic field lines in
the rotor chamber and in the sample sector of a standard d.s. centerpiece
look like?

 

Thank you in advance for your answer(s) (and time),

 

Kind regards, Karel Planken.

 

K. L. Planken

Van 't Hoff Laboratory for Physical and Colloid Chemistry

Utrecht University

H.R. Kruytgebouw

Padualaan 8

3584 CH Utrecht, The Netherlands

 

Phone: +31-30-253 2888

Fax: +31-30-253 3870

 

Please visit <http://www.chem.uu.nl/fcc/www/peopleindex/karel/karel.htm>  my
webpage!

 

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