X-ray Crystallography 1

Dr. Helen Berman

October 14, 2002

Examples of translational symmetry

Macgillavry, C. Symmetry Aspects of M. C. Escher’s Periodic Drawings.Bohn, Scheltema & Holkema, Utrecht, 1976, p. 5.

Example of how to define

a unit cell

Glusker, J. & Trueblood, K. Crystal Structure Analysis: A Primer.Oxford University Press, 1985, p. 12.

Conventions used in

defining unit cell

Blundell, T. L. Protein Crystallography.Academic Press, 1976, p. 84.

identity

Bernal, Hamilton, & Ricci. Symmetry: A Stereoscopic Guide for Chemists.W. H. Freeman and Company, 1972, p. 44.

Two fold symmetry

Bernal, Hamilton, & Ricci. Symmetry: A Stereoscopic Guide for Chemists.W. H. Freeman and Company, 1972, p. 45.

Three fold symmetry

Bernal, Hamilton, & Ricci. Symmetry: A Stereoscopic Guide for Chemists.W. H. Freeman and Company, 1972, p. 48.

Four fold symmetry

Bernal, Hamilton, & Ricci. Symmetry: A Stereoscopic Guide for Chemists.W. H. Freeman and Company, 1972, p. 50.

Six fold symmetry

Bernal, Hamilton, & Ricci. Symmetry: A Stereoscopic Guide for Chemists.W. H. Freeman and Company, 1972, p. 52.

Screw axis

Rotational and translational symmetry

Glusker, J. & Trueblood, K. Crystal Structure Analysis: A Primer.Oxford University Press, 1985, p. 94.

Symbols used to describe

different symmetry in

crystals

Seven systems

Glusker, J. & Trueblood, K. Crystal Structure Analysis: A Primer.Oxford University Press, 1985, p. 200.

Plane groupspmm

Macgillavry, C. Symmetry Aspects of M. C. Escher’s Periodic Drawings.Bohn, Scheltema & Holkema, Utrecht, 1976, p. 11.

Disallowed symmetry in

crystals

Space groups

Example from International

Tables of Crystallography

P212121

Diffraction pattern of a

duck

Holmes, K.C. and Blow, D. M. The Use of X-ray Diffraction in the Study of Protein and Nucleic Acid Structures.

Robert E. Kreeger Publishing Company, 1980, p. 120.

Diffraction from a slit

A) narrow slitB) wider slit

Illustrates reciprocal

relationship

Glusker, J. & Trueblood, K. Crystal Structure Analysis: A Primer.Oxford University Press, 1985, p. 22.

Add more slits, sharpen

pattern

Glusker, J. & Trueblood, K. Crystal Structure Analysis: A Primer.Oxford University Press, 1985, p. 28.

Diffraction from lines gives dots

Illustration of a reciprocal

lattice

convolution

Blundell, T. L. Protein Crystallography.Academic Press, 1976, p. 114.

Optical diffraction

A) latticeB) 1 moleculeC) 2 moleculesD) 4 moleculesE) row of 6 moleculesF) a small crystal

Blundell, T. L. Protein Crystallography.Academic Press, 1976, p. 113.

Example of resolution

Holmes, K.C. and Blow, D. M. The Use of X-ray Diffraction in the Study of Protein and Nucleic Acid Structures.

Robert E. Kreeger Publishing Company, 1980, p. 120.

Effect of series termination

Blundell, T. L. Protein Crystallography.Academic Press, 1976, p. 118.

Optical diffractometer

A apertureC condenser lensObject placed in plane MS lensDiffraction pattern in plane DO objective lensI recombined image

Blundell, T. L. Protein Crystallography.Academic Press, 1976, p. 110.

Braggs Law

nλ=2dsinθ

θ i s th e angl ebetwee n incidentan d reflecte d beam

d i s spacin gbetwee n planes

λ i swavelength

n i sorde r o f diffraction

Example of an x-ray

diffraction pattern

Glusker, J. & Trueblood, K. Crystal Structure Analysis: A Primer.Oxford University Press, 1985, p. 26.