- 47 Views
- Uploaded on
- Presentation posted in: General

PY4007 Lecture 3 - Catalysts

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

At the nanoscale, physics and chemistry converge

[001]

[010]

[100]

Direction vectors take square brackets

This is a (100) plane in a FCC packed material

This is a (110) plane in a FCC packed material

This is a (111) plane in a FCC packed material

Looser packing.

Closest packing.

Lowest surface energy.

Higher surface energy.

Equilibrium shape is the inner envelope of planes normal to, and passing through the end of, the free energy vectors.

Create (111) faces to give truncated octahedron.

(100) type face

(111) type face

Made from 5 tetrahedral units

Made from 20 tetrahedral units

7.5°

Here we are plotting:

(a) Show that the Fermi energy for sodium is approximately 3.1 eV (density of Na is 970 kg m-3; atomic mass for Na is 23). [Hint: Assume a free-electron model for the valence electrons of sodium.]

(b) Hence derive an approximate expression for the temperature of the metal-nonmetal transition for a sodium cluster of diameter, d. Find this diameter at a temperature of 100 K.