Dear all,
I don't know how to prepare my sample for characterization Raman. When I watch tutorial movie in youtube, they use Glass Silde, however, my friend recommend use Si wafer. So, I don't know which is better? (actually, I want to use glass slide).
Furthermore, I still don't know how make sample. (1) Drop some droplet which contain my sample (carbon+NMP) onto surface of Glass slide , and wait a day to evaporate NMP? Or (2) filtration sample to obtain solid sample and put it onto surface Glass slide? I often use #2, but the surface of my sample is very rough, not flat and when I set the position of Laser, maybe it is not accuracy.
Thanks
Hi Nguyen Duong Nguyen,
It is very possible to do the Raman characterization on a glass substrate. You can follow up the methods no. 1 you mentioned. Si wafer is usually used to calibrate your system before your glass substrate because Si peak is greatly stable. A pretreatment of your glass slide may also be needed (washing or sonication) to obtain a good attachment of your desired molecule onto it (consider also the hydrophobicity/hydrophilicity).
In general for solid samples there is no need for any sample preparations. In some cases for solid sample one may need to polish the surface (not very common however). For the liquid sample one should use a substrata that will not impact the results based on for example chemical reactions between the substrate and the liquid sample or by introducing Raman features that may cause confusion in terms of interpreting the Raman spectra. If one is using a glass slide as substrate, you may need to run a Raman spectra of the glass slide first to determine the Raman features of the glass slide before taking the Raman spectra of the sample. For SI substrate there is only one sharp peak at around 520cm-1 that is a good reference pint for calibration purpose. Another difference in using Si substrate vs. glass substrate is that Si wafers generally have a specific single crystalline structure, and depending how close is the lattice spacing of Si to that of the sample one may induce some level of directionality as well as stress in the thin film grown on Si, while glass is generally lacking a preferred crystalline direction so it will not have such impacts on the thin films. One common method for preparing thin film sample from liquids on a substrate is spin coating process.
Best of luck!
Dear Lady, I do agree with the other comments but I feel free to add one detail. If your liquid sample layer/drop is sensitive for temperature changes you have to consider the absorption of the substrate in dependence on the wavelength of the exciting laser. In the case of visible light the focussed (?) beam can heat the substrate. Regarding this aspect glass could be more suitable than silicon. Wkr, M. Herms.
Are you using an FT-Raman or a dispersive (microscope) Raman system? The sampling configuration will be different between the two and knowing your instrumentation will help in answering this question. I wouldn't use a silicon slide / wafer as the Si signal will be much bigger than the response from your sample so you will limit the dynamic range of your measurement.
By making slurry of your sample.........you can do.............
To prepare slurry... take a few mg of sample in a pastle-mortor followed by a few drops of Triton-X 100 as binder and crush till it makes slurry...............Now this slurry can be used for Raman Analysis
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