From: H. Olin Spivey <ospivey@bmb-fs1.biochem.okstate.edu>
  To  : Gresham Weatherly , rasmb@alpha.bbri.org
  Date: Mon, 6 Dec 1999 14:15:12 -0600

Re: XLA monochromator

   We most frequently use multiple wavelengths also.  Following the
recommendation of Marc Lewis, we always create a new file for each
wavelength so that we can avoid the varying wavelengths each time the
monochromator setting is changed.  We have not encountered changes in
wavelength after such a strategy to my knowledge.  Allen Minton, however,
records the wavelength scan.  His programs then look at the exact
wavelength recorded for each absorbance scan and interpolates the A
readings to the reference wavelength he desires.  If you do this, you will
want to have your wavelength scans made with about 25 repetitions in order
to get sufficiently accurate scan data.

   Olin






At 2:09 PM -0500 12/6/99, Gresham Weatherly wrote:
>I am trying to collect data at two different wavelengths during an
>equilibrium sedimentation experiment. The monochromator does not always
>collect the data at the correct wavelength, sometimes the header file shows
>that it has collected + 1 nm from the desired wavelength.  This is okay
>because I can discard these files that have been collected at the wrong
>wavelength.
>However, sometimes subsequent scans are offset even though the wavelength
>in the header file is the same.  The attached file shows three scans that
>have supposedly been collected at one wavelength, but appear to be
>collected at different wavelengths. The data collected at the second
>wavelength overlay, so I believe the system is at equilibrium.
>My question is when the monochromator collects five scans and averages them
>does it collect all five scans at the same wavelength, and is there
>anything I can do to make the XLA collect data at the right wavelengths?
>
>Thank you for any help you can give me,
>
>Gresham Weatherly
>Attachment converted: HardDrive1:overlay.pdf (PDF /CARO) (0000F27D)
>
>
>Department of Chemistry; CB# 3290
>University of North Carolina
>Chapel Hill, NC 27599-3290
>Tel: Lab (919)962-1297, Home (919)933-7837
>Fax: (919)966-3675


H. Olin Spivey                       Phone: (405) 744-6192
Dept. Biochem. & Molec. Biology      Fax:   (405) 744-7799
246 NRC                              Email: OSpivey@Biochem.Okstate.Edu
Oklahoma State University
Stillwater, OK 74078-3035