Trouble taking Raman spectra in solution.

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    Raman Spectra
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SUMMARY

The forum discussion centers on challenges faced while obtaining Raman spectra for Rhodamine B and heparin sodium in solution using a Renishaw InVia Raman microscope. Users reported that instead of detecting the expected peaks for the compounds, the spectra primarily reflected the solvents, particularly when using the 785 nm laser. The issue may stem from sample preparation techniques, such as dilution levels and the absence of appropriate sample holders, which can affect the quality of the spectra obtained.

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  • Understanding of Raman spectroscopy principles
  • Familiarity with the Renishaw InVia Raman microscope
  • Knowledge of solvent effects on Raman spectra
  • Experience with sample preparation techniques in spectroscopy
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This discussion is beneficial for chemists, spectroscopists, and researchers involved in Raman spectroscopy, particularly those working with liquid samples and seeking to optimize their experimental setups.

Pills07
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Hello everyone!
I´m new to the forum and to start participating and being part of it I have the following problem and question:

I began using a dispersive Raman system and I got spectra of Rhodamine B and heparin sodium (and anticoagulant and glycosaminoglycan) in solid form and the spectra are good,but when I take the following:
1.Rhodamine B dissolved in ethanol and deionized water.
2.Heparin dissolved in deionized water and benzyl alcohol.

I get the solvents spectra,which to me is kinda weird because at least water is supposed to be a weak Raman scatterer.To prove that I got the wrong spectra to say it somehow I took spectra of the solvents alone and what I tried to do was subtracting the spectra (as done in UV-Vis spectroscopy) still I couldn´t see any of the peaks typical for heparin nor Rhodamine.
The system used is a Renishaw InVia Raman microscope,the spectra are taken at standard and ambient conditions,we have three lasers 457 nm,515 nm and 785 nm,I used the last one.I put the samples on an eppendorf cover (in an upside down position so the liquid sample can be poured in it) because we have no sample holders nor cells available for now.
So what am I doing wrong?,is it the way the I prepare the sample,would I have to do anything regarding the laser handling? what do you think? :confused:
 
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I correct,sorry:
actually they are 4 solutions,if someone reads it as I have it in the original post then it can be thought it´s a mixture,so the four solutions I am having trouble with are:
1.Rhodamine B in ethanol.
2.Rhodamine B in deionized water.
3.Heparin in deionized water.
4.Heparin in benzyl alcohol.
 
I will suggest the obvious first; perhaps the solution is too dilute?

Claude.