### 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.

Mathematica notebook to explore the question.

Physical Chemistry I: Quantum Chemistry

Bryn Mawr College

This semester we will be covering quantum chemistry, including an introduction to quantum mechanics, molecular quantum mechanics, and spectroscopy.

Mathematica notebook to explore the question.

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

Mathematica notebook with answers

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

MP3 podcast

screencast

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.

MP3 podcast

screencast

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.

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

screencast

MP3 podcast

screencast

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

screencast

MP3 podcast

screencast

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

screencast

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

MP3 podcast

screencast

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

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

MP3 podcast

screencast

What's a cow magnet?

Accidents with MRIs

MP3 podcast

screencast

What's a cow magnet?

Accidents with MRIs