Please see attached the spectra I obtained. The abrupt change is marked with the red circle. I set the lamp switch at 340 nm. Is this change relate with the lamp change? How can I avoid this problem?
to me this looks very much like an instrumental feature such as a band switch. What kind of instrument do you use?
Regards,
Lars
, it seems to be the lamp change, deuterium to tungsten. I do no use a shimadzu, but other spectrophotometers allow you to select the wavelength where the lamp change is done (usually between 310 and 340nm) to avoid interference. Check in the control soft ware (probably it says lamp change or something like this) if you need to make measurements near the problem wavelength
Juan I clicked add before ending, probably one of your lamps is low in intensity, may be a lamp change is required, best regards
German
Dear German,
Thank you for your answer. I measured several film sample, and actually I have one sample that does not have that abrupt increase. Please see attachment for the file. I am not sure if this is due to the fact that the absorbance at around 340 nm is low, so that it is not obvious in this plot. Do you think, if I change my "wavelength for lamp change" will help?
Best,
Juan
Hi, the change will only move the "anomaly", did you check the time of use of the lamps, if you have low intensity, at low transmission, the effect could be enhanced.
regards
gg
Would check first with solutions of a yellow colour. Maybe renew correction for the 100 % line and for no light.
It seems due to the instrument.. Can you check by changing the resolution from 1nm to 1.5nm. Also check with this resolution other peaks
Simply run the buffer background and subtract it. The jump will be in the background. It is probably a shift due to new lamp. Zero the instrument over the entire range before running any spectrum.
Sorry to say, but the jump can't get eliminated by running a solvent background.
It is a common behaviour for dual light source spectrometers like yours. Both lamps have to be properly aligned mechanically and corrected for the difference in light output intensity (which was not properly done in your case). Every manufacturer has built a solution for this into the device. Please search the manual for hints to an adjustment procedure. Or else contact support...
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