X-ray Crystallography Equipment

Question 1

What is the column that removes X-rays from storage ring made of?

Answer 1

Beryllium (does not absorb x-rays)

Question 2

What does a monochromator do?

Answer 2

Ensures only one wavelength of x-ray is used

Question 3

What is the goniometer used for?

Answer 3

Positions the crystal in different orientations.

Question 4

What is the function of the beam stop?

Answer 4

Prevents unscattered x-rays reaching the detector.

Question 5

What is used to focus the beam on the crystal?

Answer 5

X-ray mirrors at super glancing angles

Question 6

What keeps the crystal at ~-180˚?

Answer 6

A cryostream

Question 7

What was originally used to detect the diffraction pattern?

Answer 7

Film

Question 8

What is currently used to detect the diffraction pattern?

Answer 8

CCD or Pilatus detectors.

Question 9

Why does the crystal need to be rotated?

Answer 9

Only certain reflections are produced at certain orientations (dictated by Ewald’s sphere), need to rotate the crystal to collect all the reflections.

Question 10

What are the advantages and disadvantages of having the detector close to the crystal?

Answer 10

The closer the detector is, the more overlap there is between spots. However, when it is closer the detector can capture high angle scattering.