This video describes and demonstrates a homemade electron paramagnetic resonance spectrometer based on the LiteVNA. We attempt to touch on the subject of quantum mechanics.

EEVBLOG thread, Experimenting with waveguides using the LiteVNA
https://www.eevblog.com/forum/rfmicr...

The Zeeman Effect:
https://courses.physics.ucsd.edu/2016...

EPR Spectroscopy: The Basics
https://www.healthcare.uiowa.edu/core...

Orbitals: What they are and how they work?
https://www.cuyamaca.edu/studentsupp...

This is not what an atom really looks like:
https://bigthink.com/hardscience/ato...

Practical Aspects
https://webhome.auburn.edu/~duinedu/e...