What is Bragg: Definition and 83 Discussions

Sir William Henry Bragg (2 July 1862 – 12 March 1942) was an English physicist, chemist, mathematician, and active sportsman who uniquely shared a Nobel Prize with his son Lawrence Bragg – the 1915 Nobel Prize in Physics: "for their services in the analysis of crystal structure by means of X-rays". The mineral Braggite is named after him and his son. He was knighted in 1920.

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  1. D

    How Does Crystal Structure Affect X-Ray Diffraction Angles?

    1. Consider a cubic crystal as shown in the figure below. As this single crystal is rotated in an x-ray spectrometer, many parallel planes of atoms besides AA and BB produce strong diffracted beams. Two such planes are shown in the figure...
  2. F

    Bragg condition reflection vs. diffraction

    I've been asking myself this question that is not entirely clear to me: the Bragg condition used to describe the constructive interference of waves on a crystal is based on the assumption of reflection. However, x-rays diffract on a crystal rather than reflect, so theoretically there is always...
  3. V

    Bragg diffraction / Solid state physics

    Homework Statement Homework Equations n\lambda = 2dsin(\theta) The Attempt at a Solution a) solving for d I get \frac{n*\lambda}{2*sin*(\theta)} = d substituting in the first value 50.85 to solve for d, with n=1 I get d= 1.754*10^-10m How do I solve the miller indices from the inter...
  4. E

    Bragg Angles + Thermal Expansion

    Homework Statement A crystal is heated from 0 to 100 degrees celcius, its lattice parameter 'a' increases by 0.17% due to thermal expansion. if we observe an x-ray reflection at a bragg angle theta= 19.3 degrees at 0 degrees celcius, by how much will theta change when the sample is heated to...
  5. N

    What causes Bragg planes in materials?

    I am having trouble understanding what exactly Bragg planes are physically. I understand how they behave, in that they act like mirrors and reflect matter waves, but what exactly is the wave bouncing off of? for instance I can guarantee any physics textbook always has a picture like...
  6. M

    Bragg Reflections: Calculating Conditions in hcp Crystal Lattice

    hi, when calculating conditions for Bragg reflections one usually works with a (1x1) cell. For example, for the hcp crystal lattice forbidden reflections are given by the condition h+2k= 3n and l=odd. Does it mean that if we double the cell, let's say to (2x2) the condition is h+2k=(3/2)n...
  7. C

    Bragg Scattering Angle for 63eV Electrons on Ni Crystal

    Homework Statement What is the Bragg Scattering angle (i.e. the angle, in degrees, between the incoming incident beam and the reflected beam) for electrons scattered from a nickel crystal if their energy is 63 eV? The spacing between Ni Bragg planes is 0.215 nm. Give your result to 3...
  8. P

    X-Ray emission and Bragg Scattering (K-Alpha and K-beta absorption)

    Homework Statement Complete this sentence. When doing Bragg scattering of x-rays off of NaCl, the first order K-Alpha peak has an energy that is ___________ the energy of the second order K-Alpha peak. Known Information It is known that the Intensity of the K-Alpha is greater than the K-Beta...
  9. E

    Difference between Bragg and Laue Diffraction?

    Hi! I am confused about the difference between the Bragg and Laue Diffraction. It seems that both arrive at the same result, but the assumptions for both are different?
  10. F

    What Are the First Five Bragg Scattering Angles for Cu X-ray Analysis?

    Homework Statement A thin polycrystalline film of Cu, with lattice parameter of 0.361 nm, is irradiated with X-rays with wavelength of 0.154 nm. Calculate the first 5 bragg scattering angles for which X-rays may be detected.Homework Equations 2dsin(\theta) = n\lambda Bragg condition for...
  11. S

    Wave length for a bragg diffraction from a incident x-ray.

    A cubic crystal with a lattice constant "a" is mounted with a [100] direction parallel to the incident x-ray beam. what would be the wave length for a bragg diffraction to occur from (110) and (111) planes? So Bragg's law is: 2d sin (theta) = n wavelength. So my thoughts are: This is...
  12. C

    Bragg Diffraction angle definitions

    I find problems on Bragg diffraction frustrating. I can't tell how the angles are defined, nor the "planes" in the crystal--they look arbitrary. Why can't I just draw a slash through the crystal at any angle I want and get diffraction off the angles I hit with the slash? Is it just that the...
  13. C

    Bragg angle and X-ray Radiation

    Homework Statement In an experiment with X-ray radiation, you use a continuous radiation from an X-ray pipe. What is the highest energy of the X-ray radiation you can get if the pipe's acceleration voltage is 40 kV? If we use radiation with double the wavelength of the maximum energy we get...
  14. C

    How can I accurately plot the Bragg curve for alpha particles?

    Goodmorning everyone, I'm new to this forum! I'm graduing in physics in Italy, and I have this problem. I want use root to plot the Bragg curve for different kinds of particles, with different initial conditions. the problem is, which function have I to plot...
  15. V

    Calculating Bragg Angle from Unit Cell in Cubic Crystal

    Homework Statement The unit cell in a cubic crystal is 2.74Å. Determine the Bragg angle for reflections from the planes (200), (212) and (-112). [sorry i don't know how to put a bar on top of the numbers] if the x-ray wavelength used is 1.54Å Homework Equations Given Bragg's condition as 2d...
  16. E

    Compton scattering and Bragg diffraction

    Hi! I know that x-rays interact with matter (compton effect). But I also know that when X-rays are incident on a crystal, they are diffracted following the Bragg's law. My question is: why is the x-ray diffracted when it is incident on a crystal, but it isn't scattered by comtpon scattering?
  17. J

    What is Bragg Detuning and How Does it Affect Bragg Gratings?

    Hi all, Could someone pls explain to me what is bragg detuning?...or some links explaining this phenomenon?
  18. A

    Bragg diffraction or reflection

    Bragg "diffraction" or "reflection" As you read about X-ray (or neutron) diffraction in solids, you come across authors who use the term "Bragg diffraction" and others that use the term "Bragg reflection". Some authors even use both terms in the same edition of the book (Kittel, 5th Ed.,, I...
  19. T

    What is the equivalence of the Bragg condition in vectorial form?

    Hello, I have a quick question regarding the bragg condition. I know that it is most often stated as 2dSin \theta=n\lambda But I have come across a case (Kittel chp9 pg 255, where it is written as (\vec{k}+\vec{G})^{2} = k I cannot really see how the vectorial case is the same as the...
  20. G

    Bragg Scattering - Need help because it is hard for me.

    I am really stuck on this problem. This entire section I have been teaching myself using the homework answers but I have no idea where to start. Thanks anyone. Question: A beam of thermal neutrons emerges from a nuclear reactor and is incident on a crystal as shown below. The beam is Bragg...
  21. D

    Bragg Reflection = Standing Waves

    Homework Statement I've got my exam in solid state physics tomorrow, and although I've understood most of the most complex subjects now, I feel I'm missing the understanding on one fundamental phenomena; Bragg reflection.. Throughout Kittel it's mentioned, that when we're at the first...
  22. T

    Bragg Scattering angle problem

    A beam of thermal neutrons emerges from a nuclear reactor and is incident on a crystal. The beam is Bragg scattered from crystal whose scattering planes are separated by 0.247 nm. From the continuous energy spectrum of the beam we wish to select neutrons of energy 0.0105 eV. Find the Bragg...
  23. Z

    Bragg cell in laser doppler vibrometer

    I know that Bragg cell used in laser doppler vibrometer (LDV) is used to give information about the direction of the velocity of the object that we measure. I also know that Bragg cell will shift the frequency of the laser beam(modulation frequency is reduced) when the object is moving towards...
  24. H

    Bragg Reflection w/ X-Ray tube voltage

    Homework Statement When a beam of monochromatic x-rays is incident on a particular NaCl crystal, Bragg reflection in the first order (ie w/ m=1) occurs at theta=20 degrees. The value of d = .28nm. What is the minimum voltage at which the x-ray tube can be operating? Homework Equations...
  25. A

    Electrons are incident on a crystal

    Q: Electrons are incident on a crystal which can be thought of as a series of reflecting planes with spacing d=0.074nm. What Kinetic Energy should the electrons be given in order that at least four diffracton maxima are observable? Attempt: The equations i think i have to use are nλ=2dsinθ...
  26. cepheid

    What Are the Miller Indices for the Bragg Reflections?

    Homework Statement An alkali halide is studied with the Debye-Scherrer technique and Cu K_{\alpha} radiation. The Bragg angles for the first five lines (in degrees) are 10.83, 15.39, 18.99, 22.07, and 24.84. Calculate (a) The lattice parameter (b) The Miller indices for the planes producing...
  27. M

    How Does Bragg's Law Determine the Angle of Gamma-Ray Deflection?

    1. Question A cubic crystal of interatomic spacing of 0.24 nm is used to select gamma–rays of energy 100 keV from a radioactive source containing a continuum of energies. If the incident beam is normal to the crystal, at what angle with respect to the incident beam do the 100 keV...
  28. B

    Bragg equation to determine the lattice constants

    Does anyone have a link or know a website where there is a table of values of lattice constants for NaCl, LiF etc? I'm asking because I was supposed to be provided with a table of values for writing my lab report, but unfortunately the lecturer seemed to have got 'array'. Any help and...
  29. C

    Distributed Strain Sensing with FO Bragg Gratings

    Not really something I would expect most people to know so I will keep it out of the Homework help section (it is not homework) I am working on distributed strain sensing with fibre optic Bragg gratings for aircraft. For those that don't know, FO Bragg gratings are a periodic variation in...
  30. A

    What is a Bragg Point: Exploring BEC of Triplet States

    Can someone please explain to me what a Bragg point is? I can't find any information anywhere as to what this is. I'm going through an article about BEC of triplet states and it mentions Bragg point. For some reason, I have not encountered this before and would appreciate any help. Thanks.
  31. P

    Energy gap and bragg refraction

    I'm asked to prove that the condition for the existence of an energy gap at the boudnry of the Brillouin zone on a 1D lattice is equivalent to the condition for Bragg refraction. I don't understand this question. Doesn't an energy gap arise solely when there is a potential? Meanwhile, Bragg...
  32. B

    Bragg Diffraction: Axes Length for FeO, CoO, NiO

    Hi, In the solid form FeO, CoO and NiO all has the NaCl-structure (simple cubic). In a series of diffraction experiments with x-rays (\lambda = 0.15406~\text{nm}) one found reflexes from the (111), (200) and (220)-planes with the following \theta-values (\theta is the angle in Bragg's law...
  33. S

    Exploring Bragg Diffraction and its Uses

    A question; What is Bragg diffraction? (X-ray scattering??) What is to be done with it? (I read something about beam splitting and diffraction of atoms by changing the momentum) Thanks.
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