Finally, the thread (you didn't know) you have been waiting for 🥳 "How can we use X-ray scattering to learn about the way the atoms sit in a #small #nanoparticle?" - lets use the Pair Distribution Function #PDF ! It's all about the neighbors 1/6 /@RPittkowski
To get information from small #nanoparticles, where periodic lattice planes are rare, we measure the X-ray scattering to very large scattering angles. This is called #Xray #totalscattering. So we need to come veeeery close with the detector to our sample.😱😬 2/6
Again, we integrate our scattering image (check up older tweets), but we are not done yet. More data treatment is necessary. We use a #Fouriertransform and transform from reciprocal (Q) space to #real #space - and there we have it, our PDF 😍3/6 
We see that we have distinct peaks at certain distances. These correspond to specific #distances between #atom #pairs . And we can use the distances to characterize the atomic structure in our sample 4/6
The distances prominent in the example, agree with the atomic pairs in a metal phase, where the atoms are densely packed (face centered cubic). We can also #fit our structural #model to the PDF data to confirm - our particles are #metallic and have an fcc #lattice 5/6
But we can get more #information from the PDF. As the PDF shows the interatomic distances in the particle, it tells us when there are no longer characteristic #distances, so the particle probably ends. This can give an idea of #size - we have around 1nm metal fcc particles 🥳6/6
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