Sparkly watches true-crime shows, and I occasionally look over her shoulder and identify instrumentation and spectra by sight. I’m surpised by how distinctive I still find them. There’s a lot of mass spectrometry, of course, and some infrared. Today I explained to Sparkly about the secret hilarity of infrared spectra, which is that each spike in the signal represents a different part of the molecule wiggling or bouncing in a different way.