Questions tagged [x-ray-diffraction]

X-ray diffraction is a method to obtain the crystal structure of a compound. This tag is also appropriate for x-ray powder diffraction.

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92 views

What is the origin of the Quadratic factor in calculation of XRD peaks?

Whenever we are to calculate the d-spacing(for cubic system) in XRD peaks with reference to Quadratic Factors we do that with the help of the formula $$\frac{1}{d_{hkl}^2}=\frac{h^2+k^2+l^2}{a^2}.$$ ...
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How were x-ray diffraction patterns deciphered before computers?

I know the general idea behind x-ray crystallography is to take a high quality crystal and place it in the path of an x-ray beam. Areas of high electron density will diffract the beam and lead to ...
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50 views

What's the definition of multi phase materials? Does it mean the different phases represent different materials?

I'm from a CS background and just trying to understand the real meaning behind multi phase materials. Following is the experiment which drove me towards this question. With the help of DFT and ...
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What kind of isomerism does Ni(PPh3)2Cl2 have and what is their IUPAC name? [duplicate]

I know that there are 2 isomers that $\ce{Ni(PPh3)2Cl2}$ have and they exist in equilibrium. I am tempted to name them cis- and trans- but it does not sound right.
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Image formation in LEEM

currently I'm studying for my master's examination in physical chemistry. The topic will be surfaces and catalysis. To prepare myself I'm reading "Surface Science - An introduction" by Oura. ...
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What is “detwinning” as a 2D crystallography technique?

The Phys.org article Iron selenide revealed as 'garden-variety iron-based superconductor' is quoted below. Normally I would hesitate to quote so much but in this case it all seems germane. Question: ...
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1answer
52 views

Obtaining atomic form factor from electron density?

I know that atomic form factors for x-ray scattering are obtained by Fourier transform of the electronic charge density. I am looking for a citable elementary source (book, review, article) which ...
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33 views

XRD-Amorphous materials

I am interested in sealing some air-sensitive samples inside of xrd-amorphous material to allow for XRD and hopefully XRD-texturing analysis. Of course, Kapton is the common material used for this ...
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X-ray structure analysis mirrored coordinates?

How to ensure, that X-ray crystallography structure analysis was done right to provide correct, non-mirrored atomic coordinates? Example: Following Wikipedia image, is generated from data taken from ...
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1answer
38 views

Why are powder XRD axes sometimes plotted in reverse?

Just plotting some powder XRD data and I wanted to know why the axes in some of the literature that I'm looking at is plotted in reverse. Is there a reason it starts at 60 Degrees (2 theta) and then ...
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1answer
51 views

Amorphous conductor transparent to XRD

I want to conduct in-situ XRD of a cathode in my battery using this coin cell with a kapton viewing window. I assume this cell configuration is the best I can find for my purpose, and that I can't ...
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What is the crystal structure for a crystal where the ratio of the squares of the angle peaks is 0.825?

I followed this and it gives an example of how to identify a crystal structure using XRD data. I have an unknown alkali halide where two peaks were found at $2\theta =25.66$ and $2\theta = 28.3$. I ...
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What can be concluded from two different values for the interplanar distance between planes of atoms in an X-Ray diffraction experiment?

I analyzed an unknown Alkali Halide crystal using x-rays from a copper source. I need to find the d-spacing for this crystal, i.e. the interplanar distance between planes of atoms. I found my $K_\...
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995 views

Why is crystallography still used in some cases for small molecule structure determination?

I was wondering for some time why in some cases x-ray crystallography and not NMR is used for structure determination of small molecules? Does crystallization maybe require a smaller amount of the ...
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1answer
502 views

Single crystal x-ray diffraction experiment backwards: from CIF to genuine set of raw data without performing actual experiment

Single crystal x-ray diffraction stands among the most complex yet trustworthy analytical techniques when it comes to structure determination of solids. But how hard it would be to simulate(fake) the ...
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433 views

How can I solve a non-cubic crystal structure?

Say I want to solve the crystal structure of barium sulfate, and I want to not only determine crystal type and the lattice parameter, but also the orientation of the oxygen atoms on the sulfate anion. ...
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What is the quantum mechanical explanation of X-ray diffraction?

One topic in crystallography that I've found a surprising dearth of information on is what the fundamental interaction behind the interaction of the X-ray and atom. Pretty much every book just treats ...
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Second Peak in X-Ray Diffraction Pattern of bcc Metal

By Bragg’s law, $$2d\sin\theta=n\lambda$$ and $$d=\frac{a}{\sqrt{h^2+k^2+l^2}}$$ Combining the two gives: $$\sin\theta=\frac{n\lambda\sqrt{h^2+k^2+l^2}}{2a}$$ By the reflection rule for bcc, there ...
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What is crystallographic equivalence?

I’ve learnt that in crystallography, there are many crystallographic directions that are “equivalent.” For example, in a cubic crystal system, the [011] and [110] and [101] directions are “...
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In powder x rd, if the crystals are randomly oriented ,why then do we get Debye rings and not random patterns?

In powder x-ray diffraction ,as I have learnt the sample is multi-crystalline.So if x-ray is diffracted through these randomly oriented crystal grains, aren't we supposed to get a random pattern?
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551 views

Why are certain reflections forbidden in body centered cubic and face centered cubic structures?

I know that for body centered cubic structures the allowed reflections only happen if h+k+l is even and reflections are forbidden is h+k+l is odd, and for basic face centered cubic structures (...
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Is the structure of a crystalized protein the native one?

When one finds the 3D structure of a protein by crystalizing it and then making a X-ray experiment, how does one know that the geometrical configuration of the crystal is the same (or even close) to ...
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1answer
803 views

Zinc oxide reduction in ethanol

I'm trying to prepare a ZnO thin film deposited on a glass substrate. The precursor solution prepared by sol gel process through dissolving 1 M zinc acetate dihydrate $\ce{Zn(CH_3COO)_2.2H_2O}$ in ...
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11k views

Why are X-rays used in crystallography?

Can any other wavelength of electromagnetic radiation be used? Why can't gamma radiation be used?
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Programs for chemical structure visualisation and drawing 2d and 3d [duplicate]

I want to create list of simple and useful software to draw molecules 2d and 3d with small description. Not necessary only freeware software. Also web-based services are interesting. Your help in ...
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1answer
1k views

Is there open source software for SEM EDX data analysis?

This can't be unique to me and would apply to anybody who has to use equipment in other departments has had departments move etc. What open source packages exist to read and potentially manipulate ...
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1answer
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Angular dependence of x-ray and neutron scattering factors

Why are neutron scattering factors essentially independent of $2\theta$, whereas X-ray scattering factors drop off with increasing $2\theta$ ?
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Are molecular optimizations in quantum chemistry really in vacuum?

I know that Gaussian (or other quantum chemical packages) assumes the molecule is alone in vacuum, that is, the molecule doesn't interact with anything, when optimizing the molecule. But I've found ...
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1answer
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How do you calculate a unit cell's dimensions from an XRD spectra?

My inorganic lab had us do an XRD measurement, but I've never been explained how to interpret the data. Question: Calculate the unit cell dimensions $a$, $b$, and $c$, for $\ce{YBa2Cu3O7}$ from ...
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1answer
311 views

The Workings of Pulse-Height Discrimination

Pulse-height discrimination is a common technique to filter out unwanted background signals from the analytical signals. But how exactly does it work? The analytical signals are not continuously ...
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1answer
167 views

Does the probability of fluorescence increase when energy of incident X-rays match the electron's binding energy?

When analyzing manganese-rich samples with X-ray powder diffraction, sample fluorescence becomes a significant effect. Is this because the incident X-rays' energy - which, if Cu K$\alpha_1$, is ...
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178 views

Is it possible to construct a 3D molecular model using x-ray powder diffraction data?

I've got x-ray powder diffraction (XRPD) data on bendamustine HCl from a patent and I want to know how to construct a 3D model using this data with software.
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137 views

Elastic scattering of x rays in 3D: the principle for XRD analysis

I have some trouble visualising scattering of x-rays in 3D, since all textbooks and examples present it in 2D. Under I will share some reflections (no pun intended) about the elastic scattering of x ...
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315 views

XRD-Shorter distance between planes than actual radius of atoms/or cell parameter

I'm solving problems related to X-ray diffraction, and I get these results which apparently are correct. My question may be dumb, but I just can't see how the interplanar distance might be shorter ...
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1answer
606 views

X-Ray Diffraction: Phase Identification Strategy

I am having some trouble with qualitative phase identification using x-ray diffraction (XRD). Here follows some basic information about the experiment: Instrument: ...