The presence of broad peak between 20-30 can confirm the existence of amorphous polymer layer on the surface of the mangnetic nanoparticles. furthermore, the decrease in intensity of the characteristic peak (magnetic nanoparticles) after modification can proof the modification of magnetic nanoparticles with polymer layer.

But you cannot confirm the structure. Multiple other procedures provides you with much better information. Zeta potential measurements are form my opinion good to prove the absorbance of a poly electrolyte. 

thanks Dr. Behbahani & Schmitt for your answers.

but Dr. Behbahani your answer isn't clear for me & i do not understand it. please explain more?

and Dr. Schmitt ; I know that we can't confirm the structure of Fe3O4@PDA with XRD completly ; but How can I measure the charge/zeta potential in laboratory (we don't have a DLS) ??please give me a paper method.

     with best regards

      mohammad reza Abdi

XRD confirms a presence of magnetic NPs and IR spectra confirmes presence of PDA (not a crystal)

thanks Mr.Ochmann

my FT-IR spectra confirmes presence of Fe3O4 and PDA. but I want to know How can I confirm the structure with XRD.

I measured also IR spectra, but Fe3O4 is not active in reflectance regime, XRD doesn't detect non-crystaline phases like polymers (there maybe a special geometry like transmission mode). Amorphous phases of anorganic sels have 1 really wide peak. And pay attention on protective foils, because the diffraction data look like deformed by one.

Using XRD for NPs stabilized by a polymeric thin film is quite complex to interpretate and not allowed formal answers. I suggest you to use TEM/X-EDS or TEM/EELS. TEM in diffraction mode provide structural information, Dark field mode will inform about size and orientation of the crystals while High Resolution mode (Lattice Fringes) should reveal the crystal limits, boundaries and amorphous thin film position. It's something quite common for a microscopist with some experience. Good luck

PL

thanks Martin & philippe for your answers.

I'll use TEM/X-EDS.

what's your opinion about Raman spectroscopy????is it useful?

Fe3O4 and all Fe2O3 polymorphs are Raman active, but that's an experience of my collegues. Is the polymer Raman active? That's a question :)

dear martin; thanks for your answers and the belowe text is my answer to your question.

the polymer is Raman active.

three strong and broad bands around 371, 490, and 682 cm-1 can be observed in the Raman spectrum of bare magnetic cores, which correspond to the T2g and A1g modes of symmetry. However, after coating with the PDA polymer shell, the intensity of these characteristic bands decreased, while two new broad bands around 1350 cm-1 and 1578 cm-1 are present in the Raman spectrum. They are characteristic bands of polydopamine, which can be attributed to the deformation of the catechol group.

Dear Abdi,

I think you can compare all the peak in your XRD characterization with data standard on JCPDS database.

Then, you can continiou to refine using Rietica.

Hopefully, it can help :)

dear Indra

thanks for your useful help

Please look at our paper  https://www.researchgate.net/publication/266078334_Micro-Raman_Spectroscopy_of_Natural_and_Synthetic_Ferritins_and_Their_Mimetics?ev=prf_pub

Article Micro-Raman Spectroscopy of Natural and Synthetic Ferritins ...

dear professor Koralewski

thanks for your paper. I read your article. it's very useful & helped me. I'll use this article in my papers; with your permission.

I think you can compare all the peak in your XRD characterization with data standard on JCPDS database.

thank you dear Elie for your answer