The above describes the operating principles of a dual beam IR spectrometer, whatever that is. It's the creation of Richard Thornley, an IB associate examiner and teacher at the United Nations International School in New York City.

What he likes to do, not just for his students but anyone that's interested in chemistry, is illustrate complex theories related to chemistry in Gary's Mod. If I knew anything about such matters, I could say authoritatively that Thornley's videos make things nice and clear. But because I cannot, I can only say that they're at the very least entertaining.

Besides, his YouTube page has enough comments from folks who all say how helpful his vignettes are. After the cut is another clip, one that states the relative energies of s, p, d, and f orbitals in a single energy level.