[RASMB] two technical questions

[virgil schirf]

Hi John,

  The instrument should reach the set speed before any scans are 
collected and should reach 40 krpm in less than 2 minutes when set to 
400 rpm/sec (max) acceleration.

The monochromator motor is not precise and normally will skip increments 
even if 1 nm is selected. I don't remember what the Beckman specs are 
but +/- 4 seems a little high.

Best regards,

Virgil

jpsumida wrote:
> Hi RASMB,
> 1) I'm working with an XLI spinning an 8hole rotor fully loaded with 8 
> cells running the instrument at 40krpm.  It takes the instrument 20 
> scans to reach top speed.  This was determined by taking omega from 
> omega-squared t, which I took from the second line of the header of 
> each absorbance scan file.  I'm not sure if this is the normal 
> behavior of this instrument and it seems to me a fairly long period of 
> time to wait for the instrument to come to speed. As I see a number of 
> posts which note that software such as UltraScan correct data 
> collected during the early part of a scan for acceleration effects, 
> perhaps this is entirely normal behavior and not worth worrying about?
> 2) If one performs a wavelength scan with the instrument in absorbance 
> mode, using a step size of 1nm increments, should one expect to 
> observe in the data file absorbance data at 1nm increments?  If one 
> observes wavelength steps that vary +/- 4nm, could this be a problem?
> Thank you in advance for any comments you may wish to share, they are 
> much appreciated.
> John Sumida
>
>
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