I'm getting a strange artifact that randomly appears in my fluorescence spectra (not constant, not always, with completely different samples, and not always at the same wavelenght within the same sample).
Is this a lamp problem? Should I calibrate the equipment?
Thanks in advance for the help.
Since these blip and dips occur randomly, they are most likely due to a speck of dust or an air bubble momentarily passing through the light beam during the scan.
Generally, this situation is not the peak of the sample we need, it may be external interference or instrument error.
Hi Cláudia Alves , for the green emission spectrum tat you have the sudden peak around 650 nm, what is the excitation wavelength? Buy any chance is it around 325 to 330 no range? If that is the case, this can be the result of the second photon absorption. Like previous researchers mentioned this can be a result of some kind of physical interference in the sample possibly otherwise.
Thank you all for your answers!
Chathura S. Abeywickrama , in this particular example the excitation was around 560 nm. I understand what you mean, but that is not the case here. The peak at 650 nm is not even my biggest concern, since it doesn't appear so often as the other irregularities you see in the spectra. Also, both types of artifacts show up completely randomly, even with different samples (nanomaterials, fluorescence standards, inorganic complexes, etc.).
I don't think its a sample problem, the equipment looked clean on the inside, and the lamp is OK. What part of the instrument would you say I should verify closely?
Thank you again for your precious help!
Claudia: dr Shapiro is an eminent spectroscopist (see his score!) and has helped out dozens of starters so I suggest you present your problem to him in detail
Harry ten Brink , thank you for your suggestion, but I don't see how much more detail could I give. The suggestion made by Adam B Shapiro is related to the sample ('a speck of dust or an air bubble momentarily passing through the light beam during the scan'), but the problem is clearly not sample related since the artifacts appear in other samples I also tested. I'm sorry Dr. Shapiro, did I misunderstood your sugestion? Were you talking about the instrument?
Thank you once more for your help,
Kind regards
Harry ten Brink Yes I did check with a blank and the problem persists.
What do you see then spikes at a given wavelength? that might indicate straylight by bubbles?
A possible instrument problem could be with the spectrofluorometer lamp. If it is fluctuating in its light output, it my need to be replaced. They don't last forever.
dr Shapiro: she mentioned that such blips are also seen for blank samples?
If the blips show up with no cuvette in the instrument, then I would attribute them to faults in the detector or fluctuations in the electrical supply.
A technician evaluated the lamp and said it's still OK. He also considered electrical fluctuations, and we now have UPS system attached to the instrument, but the problem persists.
I will try a few more tests, and if nothing works, we will re-calibrate everything.
Sorry, a little late to answer questions. At very low intensity I have such patterned artifacts showing up in my spectra. Never the same place, never the same intensity. It's annoying but that's due to a choice of the manufacturer... Really annoying when you cannot irradiate twice!
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