Trouble taking Raman spectra in solution.

In summary, Claude is having trouble getting spectra of his Raman samples. He is using a Renishaw InVia Raman microscope and is taking standard and ambient conditions. He has three lasers - 457 nm, 515 nm, and 785 nm. He put the samples on an eppendorf cover and tried to subtract the spectra, but still couldn't see any of the typical peaks for heparin or Rhodamine.
  • #1
Pills07
2
0
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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  • #2
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.
 
  • #3
I will suggest the obvious first; perhaps the solution is too dilute?

Claude.
 

1. Why is it difficult to obtain Raman spectra in solution?

Obtaining Raman spectra in solution can be challenging because the molecules are typically surrounded by solvent molecules, which can interfere with the Raman scattering signal. Additionally, the solvent may absorb or emit Raman-active light, making it difficult to distinguish the signal from the sample molecules.

2. How can I improve the quality of Raman spectra in solution?

To improve the quality of Raman spectra in solution, it is important to use a solvent that does not interfere with the Raman signal, such as water or ethanol. It is also helpful to use a low concentration of the sample in order to reduce the effects of scattering from the solvent molecules.

3. What factors can affect the Raman spectra obtained in solution?

Several factors can affect the Raman spectra obtained in solution, including the concentration and composition of the sample, the type of solvent used, and the excitation wavelength. Other factors, such as temperature and pH, can also influence the Raman signal.

4. Can I use any type of container to obtain Raman spectra in solution?

No, not all containers are suitable for obtaining Raman spectra in solution. It is important to use transparent and optically smooth containers, such as quartz or glass cuvettes, in order to minimize the effects of light scattering and ensure accurate results.

5. Are there any precautions I should take when obtaining Raman spectra in solution?

Yes, there are several precautions that should be taken when obtaining Raman spectra in solution. These include avoiding exposure to ambient light, using a stable and consistent light source, and ensuring that the sample and solvent are free of impurities that could affect the Raman signal.

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