29.2 Nuclear Magnetic Resonance spectroscopy with audio

Описание: In this in-depth A Level Chemistry lesson, award-winning science educator Dr David Boyce explores the fascinating physics behind Nuclear Magnetic Resonance (NMR) Spectroscopy — one of the most powerful analytical techniques in modern chemistry.

We begin with the historical development of NMR, tracing how early investigations into nuclear spin and magnetism led to a technique that revolutionised structural chemistry and medical imaging.

From there, we build the core theory:

🔬 Nuclear Spin Explained
What does it really mean for a nucleus to “spin”? Why do some nuclei have spin ½ while others have 3/2 or 5/2? We take a deep dive into the nuclear shell model, exploring how orbital angular momentum and intrinsic spin combine to produce higher nuclear spin states.

🧲 Larmor Frequency & Precession
Why do nuclear magnetic dipoles precess rather than simply align with a magnetic field? We examine torque, angular momentum, and the origin of the Larmor frequency, building a clear physical picture of spin behaviour in an external magnetic field.

📡 Magnetic Conditions & RF Absorption
What magnetic field strengths are required for NMR? How does radiofrequency radiation cause absorption and re-emission? We explain resonance, energy level splitting, and how precessing nuclear magnetisation induces a detectable signal.

🧪 Sample Preparation
Why are deuterated solvents essential?
Why is tetramethylsilane (TMS) defined as 0 ppm?
We walk through the correct preparation of an NMR sample for accurate and reliable spectra.

📊 Interpreting the Spectrum
Finally, we analyse the output of an NMR spectrometer:

Chemical shift

Reference standards

Why chemical shift is measured in parts per million (ppm)

How ppm allows comparison across different magnetic field strengths

This lesson bridges physics and chemistry, giving A Level students not just the “how” of NMR, but the deep conceptual “why” behind the technique.

Perfect for:

A Level Chemistry students

University foundation students

Anyone wanting a deeper conceptual understanding of NMR

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