DeBroglie Wave Nature of Matter

Outcomes You will explain, qualitatively, how electron diffraction provides experimental support for the de Broglie hypothesis. You will describe, qualitatively, how the two-slit electron interference experiment shows that quantum systems, like photons and electrons, may be modelled as particles or waves, contrary to intuition

Compton & Wave-Particle Duality Compton demonstrated that photons could behave like particles and waves at the same time: Particle Characteristics: Particles carry energy in packages Particles have momentum that can be transferred to other particles Wave Characteristics: Characteristics like wavelength, period, frequency, and amplitude. They can diffract, interfere, and produce interference patterns. They can be polarized.

Lois DeBroglie Since photons (EMR) behave like particles and waves, Lois DeBroglie suggested the following in 1923: If a photon of light has momentum that depends on its wave characteristics, then a particle (like an electron) could have wave like characteristics (like wavelength) that depended on its momentum!

Calculations – For Photons

Calculations – For Electrons This is called the DeBroglie wavelength! (Not required to apply this equation on the diploma exam!)

Electrons acting as Waves G.P. Thomson showed this wave-like behaviour of particles in 1927 He showed that electrons give a diffraction pattern similar to x-rays and light with a wavelength given by the De Broglie equation

To Recap Quantum Mechanical Model: Photons are ‘particles’ of EMR that have momentum and carry energy and display particle properties like conservation of momentum And particles like electrons can have wavelengths and display wave properties like diffraction and interference

Sample Problem What is the momentum of a 500-nm photon of green light?

Sample Problem What is the wavelength of an electron moving at 1.00x104 m/s?

Homework p. 740 #1-4