QUANTUM MECHANICS Tran Thi Ngoc Dung – Huynh Quang Linh – Physics A2 HCMUT 2016 VOCABULARY • Wave Particle Duality • Uncertainty • Heisenberg’s Uncertainty Principle • Wave Matter • De Broglie’s wavel[.]
QUANTUM MECHANICS Tran Thi Ngoc Dung – Huynh Quang Linh – Physics A2 HCMUT 2016 VOCABULARY • Wave - Particle Duality • Uncertainty • Heisenberg’s Uncertainty Principle • Wave Matter • De Broglie’s wavelength CONTENTS • Wave – Particle Duality of Matter • De Broglie’s Hypothesis – Matter wave • Diffraction of electron wave by single slit • Heisenberg’s Uncertainty Principle “„Quantum mechanics‟ is the description of the behavior of matter and light in all its details and, in particular, of the happenings on an atomic scale Things on a very small scale behave like nothing that you have any direct experience about They not behave like waves, they not behave like particles, they not behave like clouds, or billiard balls, or weights on springs, or like anything that you have ever seen.” Richard P Feynman Matter Waves DeBroglie (1924) proposed that, like photons, particles have a wavelength: l = h/p electron gun detector q Inversely proportional to momentum In 1927-8, it was shown (DavissonGermer) that, like x-rays, ELECTRONS can also diffract off crystals ! Ni Crystal Interference peak ! • We will see later that the discrete atomic emission lines also arise from the wavelike properties of the electrons in the field of the nucleus: Atomic hydrogen I(q) Electrons can act like waves!! 60 q What does this mean? In discussion section: q o “Double-slit” Experiment for Electrons Electrons are accelerated to 50 keV l = 0.0055 nm Central wire is positively charged bends electron paths so they overlap A position-sensitive detector records where they appear