What is X-ray diffraction: Definition and 58 Discussions
X-ray scattering techniques are a family of non-destructive analytical techniques which reveal information about the crystal structure, chemical composition, and physical properties of materials and thin films. These techniques are based on observing the scattered intensity of an X-ray beam hitting a sample as a function of incident and scattered angle, polarization, and wavelength or energy.
Note that X-ray diffraction is now often considered a sub-set of X-ray scattering, where the scattering is elastic and the scattering object is crystalline, so that the resulting pattern contains sharp spots analyzed by X-ray crystallography (as in the Figure). However, both scattering and diffraction are related general phenomena and the distinction has not always existed. Thus Guinier's classic text from 1963 is titled "X-ray diffraction in Crystals, Imperfect Crystals and Amorphous Bodies" so 'diffraction' was clearly not restricted to crystals at that time.
##\require{physics}##I am trying to understand how the Ewald's sphere works in the context of X-ray diffraction (XRD). I am reading from Kittel's book, as well as a few lecture series. Let me first state what I have learnt in this context (please correct me if I am wrong).
For any real lattice...
Bragg's law is schematically shown on the picture:
Two parallel and plane waves are shown which propagate towards the crystal. For plane waves, wave fronts are flat planes perpendicular to the wave propagation with infinite size. In reality, there are no plane waves. Nevertheless, they are...
Hello,
I am wondering why in all X-ray diffraction experiments used to probe or know the crystal structure of the solid they assume that the scattering process is elastic, e.g, if an X-ray with wave vector ##k\vec{n}## is incident on a sample, it will diffract with a wave vector ##k\vec{n}'## of...
Below is the measured values for the Debye rings I obtained. I have to multiply the ratio (which is (sin^2(theta_n))/(sin^2(theta_min))) by a multiplicand until I get an integer. However for the multiplicand and the values I measured I get 1, 3, 13, ??, 4, 8, ??. These should either correspond...
When we shine an X-ray beam on a crystal, according to Van Laue formulation, for a sharp intensity peak to be observed on the screen there is a specific direction ##\mathbf{\hat{n}}## , in which for all the X-rays with wavelength ##\lambda## and wavevector...
I'm reading about x-ray diffraction in the context of crystal structure determination. Usually this discussion begins with Bragg's law, $$2d\sin\theta=n\lambda,$$ where ##\theta## is the angle of incoming and "reflected" x-rays. This is the bit that bothers me. I understand that the...
Hi, I know the material being studied is FeCO3.H20 (hydrated siderite) and the wavelength for a D2 diffractometer with a Co tube is 1.79026.
In order to use Bragg's Law to calculate the peak positions, I think I need to first calculate d using the equation with the Miller indices and a which...
Hello, I have a question about this optics related problem.
The distance between atomic planes in calcite is 0.30 nm. what is the smallest angle between these planes and an incident beam of 30pm x-rays at which diffracted x-rays can be detected?
Thank you so much for the help guys!
Homework Statement
The Attempt at a Solution
Hi All,
I have two issues with this question. First of all when I put the given values into the Bragg condition for diffraction I get two different wavelengths when the question implies there is only one. Secondly, I don't know how I can...
I don’t understand why do we use power in this experiment. If we use powder, the d spacings of each crystalline will be oriented randomly, why won’t the angle of reflection changes? I don’t understand the idea of using powder in the experiment.
Thank you so much
In my x-ray crystallography data for a single crystal of NaCl using x-rays generated by Cu k alpha (154 pm), there are three peaks identified at angles of 14.155, 31.475 and 53.5 degrees.
According to http://www.nada.kth.se/~fabo02/solid/xray.pdf, these peaks must correspond to only even values...
I am trying to experimentally determine the atomic scattering factors for NaCl using Laue photography. For an NaCl crystal, the intensity of the wave scattered at the unit cell is proportional to (4⋅(fCl+fNa))2 if h,k,l are even and to (4⋅(fCl-fNa))2 if h,k,l are odd. fNa and fCl are the atomic...
For x-day diffraction maxima we have braggs law
2d*sinθ = mλ (maxima)
Is there an analogous law for the minima like
2d*sinθ = (m+1/2)λ (minima?)
Thanks!
Does anyone knows where I could find the answer to the problems in the classical book on x ray Diffraction by B. E. Warren "X-ray Diffraction" ?
It's not an easy-to-read book so I think that checking my solutions to the problems would be really helpful.
thanks
Hello
What does it mean when people say high resolution xray diffraction? What is the difference between regular Xray diffraction and high resolution X-ray diffraction?
Thank you
X-ray has enough energy to eject the electron in the atom, molecule etc. But in the x-ray diffraction electron does not eject, only oscillate with the same frequency as X -ray,why? Why does not x-ray eject the electron?
In X-ray diffraction, during the experiment a X-ray beam will create an incident and diffracted beam, but what exactly is the virtual source? I may be mistaken but isn't the source the incident beam, in the attached image, it seems to suggest otherwise?
I understand that the peak-width of diffraction data increases with increasing amounts of heterogeneous, localized (AKA "micro-") strain.
So, if you have a single crystal with atomic impurities in it that each create micro-strain in the lattice, you would expect the amount of peak-broadening...
When x-rays are incident on a crystal structure, do they diffract in the same way as light through a diffraction grating?
On the one hand, I've read that a crystal structure acts like a 3D diffraction grating. On the other hand, I have been told that x-rays induce an electric dipole moment in...
Homework Statement
A crystal composed of two fractions, one having the a cell parameters of 4.123A and the other of 3.997A are subjected to X-ray diffraction using both Cu k-alpha and a Mo k-alpha radiation. Derive the angular position of (2theta) for (100) and (110) planes.
Explain the...
Hi everyone, I'm little bit confuse about non destructive techniques such as XRD (X-ray Diffraction) and Raman spectroscopy, I know that both techniques can determine the crystal structure of the certain materials, and also, I know that XRD is working with the principle of emission of x-ray...
I'm writing a little bit of Mathematica code that should be able to make a reasonable powder diffraction spectrum. The algorithm is like this:
Take Bravais lattice and basis. Compute reciprocal vectors.
Compute structure factor (and its square magnitude)
Have triple nested loop that creates...
I'm working on a physical chemistry project that is a report on a paper that uses X-ray crystallography to characterize a protein. So I am studying X-ray crystallography more in depth than the book introduces, and I have a few questions that I couldn't really find answers to online.
1. How...
Homework Statement
It's got a diagram in it so I have just attached a picture of it.
Homework Equations
nλ=2dsinθ
The Attempt at a Solution
I've really got no idea how to proceed with this one. I think you have to consider the effect of the thin film as well. Any ideas?
In x-ray diffraction , even though its reflection is happening , we call this as x ray diffraction. why is it so?? i don't know whether it has been discussed previously here.
What would happen to the XRD pattern if instead of having spherical atoms, we had triangular atoms? I found the optical diffraction pattern for a triangular aperture, but I'm not sure if optical diffraction patterns would be the same as XRD patterns.
(My (old) background is math & computer science. I've long loved (mostly) precious opals - for their esthetics, lapidary potential, synthesis (which I've done), and how the play-of-color ("PoC") is produced.)
I recently did another couple of passes on the latter in the process of trying to...
I have a question regarding X-ray diffraction and energy conservation.
If one considers elastic scattering from a rod-like structure, the observed diffraction pattern will change as the sample is illuminated from different directions. For some directions the pattern will be point-like, and...
Does anyone have a good book that explains X-ray diffraction theory well? Stuff like interference calculations, reciprocal space, diffracted amplitudes and intensity, and the Debye formula.
Hello experts!
I have some questions related to the X-Ray Diffraction using Laue's treatment.
I have attached some images. I have marked in red what I want to ask.
Kindly tell me where did these equations come? Is there any low level physics included too, if so then kindly guide me...
Homework Statement
Consider a metal with an BCC crystal structure and atomic weight 92.91. When monochromatic x-radiation having a wavelength of 0.14 nm is used, the angle of diffraction (2*theta) for the (211) set of planes in this metal occurs at 41.148 ° (first-order reflection)...
How do get the d spacing from XRD data, using braggs law. I am unsure how to actually obtain the value of d. I have attached the file as a text file with the data in.
Many thanks for the help.
I know it is a simple question but I cannot find the answer. Why is the [001] diffraction peak not observed in XRD but [004] peak is observed. Thank you.
I'm looking for a book that might teach me how to read diffraction patterns and infer structure. I'm also interested in the history of the technique. This is mainly so I can explain it with confidence to high school students and college freshmen as a teacher.
I feel like I never really went...
Hi, I was conducting an experiment on a material using XRD and I investigated two cases. One case is the presence of outside electric potential, that is, the material being connected to a electric circuit. The other case is the absence of this electric potential. I found that the two XRD...
Hi, I was conducting an experiment on a material using XRD and I investigated two cases. One case is the presence of outside electric potential, that is, the material being connected to a electric circuit. The other case is the absence of this electric potential. I found that the two XRD...
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Hope somebody can help me.
I am studing perovskite hydride CaCoH3 using X-ray diffraction. CaCoH3 crystallizes with a cubic in space group Pm-3m. At phase transtion point, all peaks weakened gradually, and...
Homework Statement
X-ray diffraction is made with a copper tube as x-ray source. The tube generates molybdenum x-rays with a wave length of 0.709 A (A=Angstrom). In the interval 40-160 degrees 2theta reflections are found under the following angles:
40.450 degrees
58.408
73.398
86.995...
Hello all,
I have a basic question with the theta-2theta technique in XRD. Here it is:
If I have a single crystal material and I perform the above mentioned characterization. Should I get one diffraction peak associated to the orientation of the bulk crystal or should I get many peaks...
Homework Statement
http://b.imagehost.org/0607/Question_7.png
Homework Equations
[PLAIN][PLAIN]http://d.imagehost.org/0813/Untitled_6.jpg
The Attempt at a Solution
I was able to get question b, which ends up being 73pm, but as for questions a and c, I was unable to come up with...
In the book of the Dr. Ronald Askeland the problem about x-ray diffraction use the next planes indices to calculate the interplanar distance, but I don't understand why to use such planes indices? Are these planes all of planes in a cubic structure?
(111)
(200)
(211)...
This is not really a homework question but a more general plea for an explenation from someone! :)
In x-ray diffraction, you get a graph with different peaks that are particular to the composition of your sample. But, why are some peaks are of higher intesities then others? What is it about...
Homework Statement
First-order Bragg diffraction is observed at 25.9degrees relative to the crystal surface, with spacing between atoms of 0.26 nm.
a)What is the wavelength of the X-rays?
b)At what angle will second order be observed?
Homework Equations
m\lambda=2dsin\phi
The...
Homework Statement
Okay so, I was hoping someone out there might be able to assist me with a Mineralogy problem I have. The concept is based around X-Ray Diffraction.
The question:
Derive a diffraction equation from the illustration below that relates the reflection angle (theta) to the...
Homework Statement
An X Ray beam (wavelength 10^10m) is incident upon a sample of a powdered crystalline material. At a distance of 5m from the sample a flat detecting film has been placed. A pattern of 2 circles have been recorded on this film (radius 2cm and 3.5cm).
What crystal spacing...
We all know, Bragg's law , n\lambda=2dsin\theta
where 2dsin\theta=path difference.
In the derivation of the path difference we take the two incident rays to be parallel which is perfect BUT we take reflected rays also to be parallel.How can this be since the reflected rays have to MEET for...
1. In satisfying the Bragg's law, n\lambda=2d\sin\theta, n is typically assumed to be one, which explains why we see only one peak for a particular plane (say [400] plane for silicon). But I really don't see why n=2 should not appear as an equally strong peak..?
2. Is the Fourier transform...
I want to find which elements and planes the intensity peaks in this graph comes from. The X-rays in the diffractometer are have a wavelength of 0.709 Å. The 2 \theta values for the peaks (including double peaks) are: 11.84, 19.56, 20.04, 23.28, 33.88 and 39.16.
Nickel, iron, silicon...