Confocal Raman Microscopy Spectra Issue

[jackieferro]

Hi all. I have been having some issues with obtaining spectra of some proteins and gums using the Confocal Raman instrument. I can't seem to see any peaks through the S/N. They are pure raw materials, in powder form. Does anybody have any tips? Does temperature make a difference? Dissolving in water/solvent? Is there a trick on the instrument? I use a 532nm laser.

[elvera33ford · Accepted solution]

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@jackieferro dog whistles app wrote:

Hi all. I have been having some issues with obtaining spectra of some proteins and gums using the Confocal Raman instrument. I can't seem to see any peaks through the S/N. They are pure raw materials, in powder form. Does anybody have any tips? Does temperature make a difference? Dissolving in water/solvent? Is there a trick on the instrument? I use a 532nm laser.

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Hello,
For protein and gum powders, strong fluorescence from the 532nm laser is likely masking your Raman signal. The best approach is to switch to a longer wavelength laser (e.g., 785nm or 1064nm) if available, as this significantly reduces fluorescence. If not, try lowering laser power, increasing acquisition time, and potentially "photobleaching" the sample with extended exposure. Dissolving in water can also help by reducing scattering and sometimes quenching fluorescence, but be mindful of solvent peaks and dilution. Ensure proper focus and instrument alignment for optimal signal collection. Temperature typically doesn't directly improve spectral quality but can cause sample degradation at high laser power.

[jackieferro]

Thank you so much!! I was going to try a 785nm laser today, I'll also play with less laser power too. I greatly appreciate your knowledge and advice 🙂 

[hazijames]

Thanks for the question! With powdered raw materials, signal-to-noise can be a challenge in Raman. Try gently pressing the sample to improve contact or consider using a different laser wavelength if available. Temperature can affect spectra slightly, and dissolving in water might help isolate peaks, but be cautious—solvents can introduce their own signatures.