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Fourier transform (see Cowley Sect. 2.2)

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Presentation on theme: "Fourier transform (see Cowley Sect. 2.2)"— Presentation transcript:

1 Fourier transform (see Cowley Sect. 2.2)

2 Fourier transform (see Cowley Sect. 2.2)

3 Fourier transform (see Cowley Sect. 2.2)

4 Fourier transform (see Cowley Sect. 2.2)

5 Fourier transform

6 Fourier transform

7 Fourier transform

8 Fourier transform

9 Scattering of x-rays by single electron (Thomson)
(see Cowley sect. 4.1)

10 Scattering of x-rays by single electron (Thomson)
(see Cowley sect. 4.1)

11 Scattering of x-rays by single electron (Thomson)

12 Scattering of x-rays by single electron (Thomson)

13 Scattering of x-rays by single atom
For n electrons in an atom, time-averaged electron density is

14 Scattering of x-rays by single atom
For n electrons in an atom, time-averaged electron density is Can define an atomic scattering factor

15 Scattering of x-rays by single atom
For n electrons in an atom, time-averaged electron density is Can define an atomic scattering factor For spherical atoms

16 Scattering of x-rays by single atom
Need to find (r) …. A QM problem But soln for f() looks like this (in electron scattering units)

17 Dispersion - anomalous scattering
Have assumed radiation frequency >> resonant frequency of electrons in atom … frequently not true

18 Dispersion - anomalous scattering
Have assumed radiation frequency >> resonant frequency of electrons in atom … frequently not true Need to correct scattering factors f = fo + f' + i f"

19 Dispersion - anomalous scattering
Need to correct scattering factors f = fo + f' + i f" 5 f" 1 2 K f'

20 Atom assemblies (see Cowley sect. 5.1)

21 For this electron density, there is a Fourier transform
Atom assemblies (see Cowley sect. 5.1) For this electron density, there is a Fourier transform F(u) is a fcn in reciprocal space

22 Atom assemblies (see Cowley sect. 5.1)

23 Atom assemblies

24 Atom assemblies For single slit, width a & g(x) = 1 If scatterer is a box a, b, c

25 Atom assemblies For single slit, width a & g(x) = 1 If scatterer is a box a, b, c For periodic array of zero-wiidth slits

26 Atom assemblies This requires ua = h, an integer. Then Finally

27 Atom assemblies This requires ua = h, an integer. Then Finally


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