website stat Chemistry 221

Saturday, April 01, 2006

Master Class: Reprise of the Pocket NMR

Why does MRI require high magnetic fields? Why is it such a low energy technique compared to X-ray?

Mathematica notebook to explore the question.

Friday, December 02, 2005

Wrapping Up: Reviewing normalization, orthogonality; A closer look at basis functions

A Mathematica exercise to review the finer points of orthonormality. We explore these concepts by comparing the behaviors of Slater type orbital basis functions and Gaussian basis functions (the latter are widely used in quantum calculations of molecular wavefunctions).

Mathematica notebook with answers

Monday, November 28, 2005

The last lecture

In which we say good-bye...and consider how a laser "amplifies" light.

MP3 podcast

The truly dedicated student can build a laser by following the directions at Sam's Laser site. Lasers can be built from a number of different materials, including Jello.

Monday, November 21, 2005

Fiat Lux! Population inversion is the key to successful lasing

Population inversion is a key feature of a system which be used to construct a laser. A system in thermal equilibrium follows Boltzmann's statistics, in which the number of molecules in higher energy states is smaller than the number in the lowest energy state. Lasers require that you have a non-equilibrium situation established, in which more molecules are "stuck" in an excited state than are currently in a lower energy state. This phenomenon is called population inversion. A second feature of lasers is that the emission process(the release of a photon when a molecule or atom relaxes from an excited state to a lower energy state) can be stimulated, or enhanced by the emissions from other molecules. This is where the "se" in the name comes from! (LASER = Light Amplification by Stimulated Emission of Radiation).

MP3 podcast

Friday, November 18, 2005

Lumos! The Quantum Mechanics of Harry Potter

We wrap up NMR and begin to consider the quantum mechanics behind lasers. Lasers are magic wands for chemists, making it possible to explore what happens in chemical processes on very short time scales. Lasers are ubiquitous tools in everyday life, too. Grocery store scanners and CD players use lasers to read information, an when you "burn" a CD, a laser is used to literally score the material.

MP3 podcast

Wednesday, November 16, 2005

A Pocket NMR?

Could you build an NMR that could fit in your pocket? The effect of magnetic field on the splitting between nuclear spin states. What would happen if you walked through a very strong magnetic field? Say a million Tesla field? Are there such fields? We propose building a pocket-sized NMR from a cow magnet. It could be done, if you're not interested in very high resolution.

MP3 podcast

A list of very strong magnetic fields, the strongest are found in rare stars.

Monday, November 14, 2005

Magnetic Personalities: NMR

The quantum mechanics of nuclear spins. How a magnetic field splits degenerate spin states of at nuclei, setting the stage for NMR.

MP3 podcast

What's a cow magnet?
Accidents with MRIs