Quantum Chemistry and Spectroscopy - Quantum Chemistry 5.7 - Anharmonicity and Overtones

Short lecture on anharmonicity and overtones of the harmonic oscillator. The harmonic oscillator quantum mechanical model for the vibrations of diatomic molecules approximates the electronic potential energy surface as a quadratic function. This leads to a selection rule in which the quantum number can only change by one during a photon absorption or emission process. This approximation breaks down away from the equilibrium bond length, leading to anharmonicity in the potential energy. This anharmonicity breaks the selection rules, and allows for overtones, where the quantum number changes by more than one. Anharmonicity leads to greater decrease in the energy as the quantum number increases. Notes Slide: http://i.imgur.com/hYkSyD0.png --- About TMP Chem --- All TMP Chem content is free for everyone, everywhere, and created independently by Trent Parker. Email: [email protected] --- Video Links --- Chapter Playlist: https://www.youtube.com/playlist?list=PLm8ZSArAXicL4kdvchwcgETYWXlt-HyzH Course Playlist: https://www.youtube.com/playlist?list=PLm8ZSArAXicL3jKr_0nHHs5TwfhdkMFhh Course Review: https://www.youtube.com/playlist?list=PLm8ZSArAXicLTRn3cJyyU1TiU7n_Pp4X1 Other Courses: https://www.youtube.com/playlist?list=PLm8ZSArAXicIXArfap9Tcb8izqRPvE0BK Channel Info: https://www.youtube.com/playlist?list=PLm8ZSArAXicLlGO4Rvpz-D6vX8MFbOn4V --- Social Links --- Facebook: https://www.facebook.com/tmpchem Twitter: https://www.twitter.com/tmpchem LinkedIn: https://www.linkedin.com/in/tmpchem Imgur: https://tmpchem.imgur.com GitHub: https://www.github.com/tmpchem --- Equipment --- Microphone: Blue Yeti USB Microphone Drawing Tablet: Wacom Intuos Pen and Touch Small Drawing Program: Autodesk Sketchbook Express Screen Capture: Corel Visual Studio Pro X8