We get these beautiful 2D images from where the #scattered#X-ray beam hits the detector plate. What you see below is the scattering recorded for LaB6 - not surprising that we use it as a standard for calibration when you look at the beautiful #rings 2/6
By radial integration we get a 1D diffraction pattern, which shows distinct Bragg peaks for each ring on the 2D image. I made a very boring #GIF where you can see how the #rings relate to #peaks in the pattern 3/6
Such a a beautiful #diffraction pattern we get for powder #crystalline samples. The #periodic lattice planes reflect the X-rays periodically which leads to interference. Maybe you remember #BraggsLaw 🤓 4/6 (image credit @kirsten_mj)
We can identify many #crystalline compounds based on their #diffraction#pattern which serves as a kind of #fingerprint and can be compared to #database structures. There exist many databases with hundreds of thousand structures - a good start to identify your structure 5/6
But what happens when we #go#nano ? By downsizing the crystal we lose most of the periodic lattice planes - so no more beautiful rings💍or Bragg peaks 🤔Not to worry, we can still get structural information - from #PDF (not the #fileformat 📰) - but that deserves its own🧵6/6
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Today we’ll refresh our knowledge of some of the battery terms. Let’s start from the beginning: we call a battery a device that converts chemical into electric energy using redox reactions. To narrow it down, let’s focus on batteries which use Li (Li-ion batteries).
image:iStock
It is a secondary (rechargeable) battery which uses reversible reactions with Li-ion to store energy.
fig: https://t.co/P4WUqJLAp4ul.org
Redox (oxidation-reduction) reactions involve transfer of electrons between two substances. As a result of gaining or losing electron, oxidation state of the substances changes.
BS job="a form of paid employment that is so completely pointless, unnecessary, or pernicious that even the employee cannot justify its existence even though, as part of the conditions of employment, the employee feels obliged to pretend that this is not the case."
I promised that I would talk about career opportunities after the PhD and other @AltAcChats using a university-organized event that I attended this week.
Well, I was recommended not to, sorry!
However, this book (50% read atm) is helping me clarify that.
Imagine that you design the perfect cake. Due to the combination of different layers of ingredients, it will have awesome unrealistic properties. A #meta cake!
But: will the structure withstand the temperatures needed during baking?
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