Why does each element have its own unique spectral signature? how doe emission lines and absorption lines arise? This lecture is the second part of a two-part exploration of matter and light, looking at how the unique spectral-line signatures of atoms are a reflection of their internal electron energy-level structures. Topics include energy level diagrams for atoms, excitation, de-excitation, and ionization. There will be a short demonstration with gas-discharge tubes and slide-mounted diffraction gratings. For podcast listeners, the last portion of the class is the demo, for which we do not unfortunately have the resources to videotape. Recorded 2007 Oct 25 in 1000 McPherson Lab on the Columbus campus of The Ohio State University.