[RASMB] Fwd: XLA NEW Jumping wavelength problem

[Katharina Spiegel]

>
>Dear RASMB Colleagues,
>
>I am encountering a phenomenon with our XLA which hopefully one of 
>you has seen already and can help me out with practical advice.
>
>We started to see a change in wavelength during velocity scanning 
>despite setting the instrument to continuous scanning of one single 
>wavelength only. Admittedly, "starting to see" means actually that 
>we "started to look", so I don't know exactly for how long we have 
>had this problem. Please view the attached scan records. Our service 
>engineer remains undisturbed, since he considers these changes 
>"within specs", but pressed harder for an explanation/solution he 
>inquired internally and came back with the following explanation:
>
>Since the delay calibration was not switched off the instrument 
>performs it prior to each scan  thereby routinely moving the 
>monochrometer to 500nm. Switching back and forth between 500nm and 
>our scan wavelength of 220nm is then causing the variation. He 
>suggested to speed up the rotor to the desired speed and run the 
>delay calibration once, switch it then off (check NO DELAY 
>CALIBRATION under options) and then "start the run" Obviously, this 
>approach needed to be altered to 1) fill rotor with mock filled cell 
>and counterbalance 2) spin it up to run speed and acquire one scan 
>with delay calibration 3) stop XLA and reload rotor with sample 
>cells 4) program run conditions with delay calibration switched off 
>5) start velocity run.
>
>Short of time I did it this way for my most recent velocity run, and 
>the problem nevertheless remained. I take this as further evidence 
>that there is a instrument problem -one which my service engineer 
>apparently has not yet seen or at least is reluctant to acknowledge 
>as a problem. Therefore, I am looking for something to tip him off 
>as to what he should be looking for.
>
>I truly hope some of you have some ideas/suggestions what to do about this.
>
>Kind regards,
>
>Kate
>
>
>
>>
>>
>>Cell 1:
>>00001.RA1:R 1 04.0 60000 0000541 1.6990E10 220 1
>>00002.RA1:R 1 04.1 60000 0000796 2.7040E10 220 1
>>00003.RA1:R 1 04.1 60000 0001059 3.7450E10 220 1
>>00004.RA1:R 1 04.1 60000 0001319 4.7710E10 220 1
>>00005.RA1:R 1 04.1 60000 0001580 5.8060E10 221 1
>>00006.RA1:R 1 04.1 60000 0001834 6.8080E10 220 1
>>00007.RA1:R 1 04.1 60000 0002096 7.8380E10 220 1
>>00008.RA1:R 1 04.1 60000 0002350 8.8450E10 220 1
>>00009.RA1:R 1 04.1 60000 0002611 9.8720E10 221 1
>>00010.RA1:R 1 04.0 60000 0002875 1.0910E11 220 1
>>00011.RA1:R 1 04.1 60000 0003137 1.1950E11 219 1
>>00012.RA1:R 1 04.0 60000 0003394 1.2960E11 220 1
>>00013.RA1:R 1 04.0 60000 0003666 1.4040E11 220 1
>>00014.RA1:R 1 04.0 60000 0003923 1.5050E11 220 1
>>00015.RA1:R 1 04.0 60000 0004175 1.6040E11 220 1
>>00016.RA1:R 1 04.0 60000 0004430 1.7050E11 220 1
>>00017.RA1:R 1 04.0 60000 0004683 1.8050E11 220 1
>>00018.RA1:R 1 04.0 60000 0004942 1.9070E11 220 1
>>00019.RA1:R 1 04.0 60000 0005193 2.0060E11 220 1
>>00020.RA1:R 1 04.0 60000 0005446 2.1060E11 220 1
>>00021.RA1:R 1 04.0 60000 0005707 2.2090E11 219 1
>>00022.RA1:R 1 04.0 60000 0005966 2.3120E11 220 1
>>00023.RA1:R 1 04.0 60000 0006236 2.4180E11 220 1
>>00024.RA1:R 1 04.0 60000 0006492 2.5190E11 221 1
>>00025.RA1:R 1 04.0 60000 0006761 2.6250E11 220 1
>>00026.RA1:R 1 04.0 60000 0007026 2.7300E11 220 1
>>00027.RA1:R 1 04.0 60000 0007280 2.8300E11 220 1
>>00028.RA1:R 1 04.0 60000 0007531 2.9290E11 220 1
>>00029.RA1:R 1 04.0 60000 0007786 3.0300E11 220 1
>>00030.RA1:R 1 04.0 60000 0008034 3.1280E11 220 1
>>00031.RA1:R 1 04.0 60000 0008295 3.2310E11 220 1
>>00032.RA1:R 1 04.0 60000 0008553 3.3330E11 220 1
-- 
*****************************************************************
Katharina Spiegel, Ph.D. 		Research Assistant Professor
Off:	847-467-6533		Manager, Keck Biophysics Facility
Lab:	847-467-6534		Northwestern University, Dept. BMBCB
Fax:	847-467-6489		2153 N. Sheridan Road
Email: k-spiegel at northwestern.edu	Evanston, IL 60208 USA

http://www.biochem.northwestern.edu/Keck/keckmain.html

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