29.2 Nuclear Magnetic Resonance spectroscopy with audio скачать в хорошем качестве

29.2 Nuclear Magnetic Resonance spectroscopy with audio

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 Subscribe for more advanced chemistry explanations with clarity and rigour.