Interaction of Light with Matter28 Aug 2008CHEM 5161CHEM 5161Rainer VolkamerWave Particle Duality• Huygens “planar wavefront” vs Newtons “Corpuscular Theory”, 1600’s• Young and Fresnel, early 1800s “Double slit experiment”wave– Maxwell, late 1800s “Maxwell equations”• Max Planck, 1901 “Black body radiation”waveparticle• Albert Einstein, 1905 “Photoelectric effect”, E = hνparticleYoung and Fresnel, 1803“D bl li i ”“Double slit experiment”Albert Einstein, 1905“Ph l i ff ”“Photoelectric effect”Photoeffect cont.Wave Particle Duality• Huygens “planar wavefront” vs Newtons “Corpuscular Theory”, 1600’s• Young and Fresnel, early 1800s “Double slit experiment”M ll l t 1800 “M ll ti ”wave–Maxwell, late 1800s “Maxwell equations”• Max Planck, 1901 “Black body radiation”•Albert Einstein 1905“Photoelectric effect”E=hν =mc2waveparticle•Albert Einstein, 1905 Photoelectric effect, E = hν = mc2The birth of quantum mechanicsparticle• Niels Bohr, 1913 “Explanation for the Balmer Series of the hydrogen atom”• De Broglie, 1924 “all matter has wave like properties“, λ = h/p• Erwin Schroedinger, 1926 “theoretical framework of quantum mechanics”W H i b 1927 “ t i t i i l ”ΔEΔt h/2•Werner Heissenberg, 1927 “uncertainty principle”, ΔE Δt ≥ h/2πThe hydrogen atom - Balmer SeriesExamples de BroglieExamples de Broglie•What is the momentum and the de BroglieWhat is the momentum and the de Broglie wavelength associated with a human weighing 70kg and running at 20 km/hr ?weighing 70kg and running at 20 km/hr ?Wh t i th t d th d B li•What is the momentum and the de Broglie wavelength of an electron accelerated th h lt f 100 V ?through a voltage of 100 V ?Schroedinger Equation for the hydrogen atomhydrogen atomFactorization of the wavefunction in polar coordinates:Copenhagener InterpretationRadial component of the wavefunctionRadial component of the wavefunctionCopenhagener Interpretation contAngular component of the wavefunctionAngular component of the wavefunctionQuantum numbers of atomsMolecules: Franck Condon Principle(determines line intensity)(determines line intensity)Born Oppenheimer approximation:•way to simplify Schroedinger Equationway to simplify Schroedinger Equation• separate electronic and nuclear portionof the wavefunctionWhy bother ?Why bother ?•Quantum mechanics is a theoryQuantum mechanics is a theory• Spectroscopy provides the only (and powerful) means to verify predictionspowerful) means to verify predictions• Information that can be obtained:–Chemical functionalityChemical functionality– Chemical bonds–Potential energy surfacesPotential energy surfaces– Reaction dynamics–Biological and biomedical