Hi, I would like to perform some Raman study to a moisture sensitive material. What we usually do, it's like mentioned in other questions in the forum, is to put the material (powders) between two glass slide and seal the gap with plastine clay (the toy clay for children) in a glove box. The problem is the slight amount of moisture in the clay will deteriorate the material and my results are not reproducible. So i would like to know if anyone knows any airtight Raman sample holder or any other way to perform Raman study for air sensible sample?
There are some heating/cooling stages available for Raman machines on the market. These stages also provide inlets for evacuations or gas intake, see e.g. Piketech S-100R, Linkam THMS600 Stage.
before to study your sample by Raman, we need to know your study target, either just to measure its Raman spectra or correlate to its properties by variable Raman spectra under different conditions? to start with, it is a good practice to measure your materials without any protection!
I measured Raman spectroscopy of many moisture sensitive matetials without any protection against materials exposure time. Visually you can see your samples changing with exposure time. by raman spectra, you can see the decrease of the intrinsic peaks intensity of the materials under study and increase of those of water. somtimes you could pick up some new peaks due to interactions of the moisture sensitive materials and water. The criticle points, for better and good quality data, are that your comfiguration of measurement and the time gap between each aquisition.
Hello Yanlong,
the best way would be to carry out your investigations within a vaccuum chamber. If this is impossible, you must prepare your samples within a glove box. You transfer your sample into a glovebox which is filled with an inert gas (dry nitrogen). Then you operate as described. Your airtight samples you can investigate in air. You must control the outer side of the window that it is clean.
It is important: No contact with air of all materials whereas the whole preparation process.
With Regard
R. Mitdank
Rüdiger Mitdank Thank you very much. Yes I have to prepare everything in the glove box, a vacuum chamber is a good proposition as well. Do you have any ideas about how to make a thin transparent vacuum or is there any commercially available thin/transparent vacuum chamber?
Artem V. Lunev Thanks a lot, that really does help. But it's not very cost effective to use environmental chamber just for the purposed of sealing. This is a good alternative if i can not find any other airtight sample stage.
Jp Wu That's a good point. The purpose will be more study both the original unaffected Raman Spectra and air-exposed Raman spectra to have comparaison and information about this material
Yanlong Zhou A much simpler solution would be to use a vacuum sealer machine to form a transparent air-tight enclosure for your sample that would still be (almost) transparent to the laser. I haven't tried this, but I think you should still be able to pick a decent signal from your sample. What do you think?
In that case, the simpliest way would be in stepwise shown below:
a, transfer your sample onto a microscope glass slide and then put a same size thin glass cover slide above the sample;
b, press gently and do not break the top cover slide; －make two slides parallel to each other; －do not leave visible empty space inside the material region, particularly in the cenre;
c, carefully seal the edge of two slides by a sellotape.
d, move the sealed slides to the sample stage of your equipment.
all steps should be done in a glove box.
If your sample's area is large enough, the measurement of spectra on the centre region of your prepated sample would be free of impact of your sample's absorption of moisture during measurement.
Jp Wu Artem V. Lunev
Thank you again for those propositions. I finally find an environmental air tight Raman sample holder, I need still do some modification of this sample to perform my study. As regards to the glass slides with tape idea, it is indeed a great idea, I thought about this as well. I'll try both ways.
Yanlong Zhou could you please share what sample holder you used for your purpose?
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