Homework 4
Chapter 3
5, 6
3.) Polymers crystallize in asymmetric lamellar crystallites with thickness of 50 to 100Å and lateral dimensions of 1,000 to 10,000Å. The crystalline c-axis is generally in the thin direction but reflections from all planes are generally very broad. In the context of the Scherrer equation (3-13 pp. 102) can this be explained?
4.) a.) Demonstrate how the parameter q = 4p sin(q)/l is related to the momentum transferred when a neutron at velocity v interacts with a fixed nucleus to elastically change direction by an angle 2q. Use Bragg’s Law and equations from Appendix 2 pp. 499. (q = 2p H from appendix 1 pp. 488.)
b.) It is often said that expert diffractionists "think in inverse-space". By glancing at appendix 1 (pp. 480) and from class notes why might this be advantageous?