Chemistry 120A Fall Semester, 2008. Problem Set 1 Due Wednesday September 3, 2008. 1. The Davisson-Germer experiment of the diffraction of electrons by an ordered metal surface gives a nice illustration of the validity of the de Broglie relation connecting the particle-like properties of electrons (their momentum) to their wavelike properties (their wavelength, which causes diffraction if the wavelength is the same as the interatomic spacing). (a) A 40eV beam of electrons shows no diffraction from a silver surface, a 54eV beam exhibits a clear diffraction pattern. By 60eV the diffraction structure is again largely lost. Work out the wavelengths for these 3 beam energies. (b) If one were worried about damage to the surface caused by the energy of the electrons necessary to cause diffraction, one could consider using a beam comprised of different particles. Work out the energy of a beam of helium atoms that could exhibit diffraction on the same surface and discuss whether or not this is a gentler probe. 2. Consider an electron that is initially far from a proton and has no kinetic energy.
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This note was uploaded on 09/28/2009 for the course CHEM 120A taught by Professor Whaley during the Spring '07 term at Berkeley.