Through characterization processes like XPS for instance, we can understand if there are absorbed organics to the outer surface of the particles even we can know from which moieties they are absorbed onto the surface.
Through which characterization methods can one detect the organics inside the crystalline particles?
FTIR May help in getting an understanding about it through the vibrational frequencies in the spectrum which are characteristic of stretching and bending in plane and out of plane vibrational modes for various structural characteristics.
The very last choice can be STEM-EELS. You can monitor the ELNES fingerprint of carbon in your crystalline particles. The process however, may need FIB milling of your particles in order to have a very precise EEL spectroscopy.
Dear Dr. Kulkarni and dear Mr. Upadhyay,
thank you for your answers. I still doubt how one can differentiate between the attachment of additives on the surface and trapped inside the particles through FTIR.
Best,
Dear Hamid,
Thank you very much for your answer. I believe that this method works suitably to detect the additives trapped inside the particles through FIB it can collect the fingerprints of the main elemental components of the additives (e.g., C, O, and N). However, I doubt if through FIB, the additves at the interface of the milled particle get deteriorated.
Best,
Hi Hamid, if organics remain trapped inside the particles, you can try using TGA analysis. With TGA (TA) you will observe when organics are released at their boiling or sublimation temperature. By using DTGA (DTA), then you will obtain these temperatures presicely. Best regards.
YEs, TGA analysis will help to differntiate between trapped versus surface adsorbed. YOu will get two distinct peaks. YOu can keep a control free organic compound and understand its TGA profile. Also if it is a crystalline compound, then you can do XRD. If the actives are trapped, it would affect the d-spacing which will be very well reflected in its XRD spectrum. You can use your free inorganic material as a control. Hope this helps
If you have your sample in the form of powder, and possess at least 5 to 6 mg, then you can do the CHNS analysis, which is simplest, but this will not help you to distinguish the carbon content say on the surface and inside the bulk.
In case you like to distinguish what is on the surface and what is inside, then do depth profiling techniques like Auger analysis or SIMS coupled with depth profiling, which will remove layer by layer, and do the chemical analysis.
Dear Professor Sreenivas,
Thank you very much for your informative answer. In the case of the presence of organic additives, will these techniques make any deterioration caused by the beam on the organic parts? And if yes, are there any ways to avoid it?
Best regards,
Amin
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