CHAPTER 3: XRAY CRYSTALLOGRAPHY

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CHAPTER 3 X-RAY CRYSTALLOGRAPHY
We know that crystal structure is really, really
important, but how do we know what the structure
is?
X-ray crystallography!
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GENERATING X-RAYS
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Electron Orbitals Probability Waves

• The QUANTUM MECHANICAL model of the atom
  describes electrons in terms of probability
  distributions (for lack of a better term) that
  can have only discrete values of energy

Harking back to a previous lecture
Bohr Model
Quantum Mechanical Model
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X-RAY SCATTERING
Like any wave, an x-ray photon will scatter when
it bumps into something that is about the same
size as its wavelength. Compare how water waves
scatter.
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SCATTERING FROM TWO ATOMS CAN BE CONSTRUCTIVE
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OR DESTRUCTIVE
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CONDITION FOR CONSTRUCTIVE INTERFERENCE
Braggs law
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A DIFFRACTOMETER MEASURES THE INTENSITY OF
DIFFRACTED X RAYS
sample
x-ray source
x-ray detector
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AND PRODUCES DATA LIKE THIS
(if you are lucky)
What is the smallest d-spacing that can be
detected with a given wavelength?