By asking about the"glow" of a plasma, I assume you mean the characterization of certain plasmas that "emit coherent visible-band electromagnetic waves (light). read more
The important take-away is that a stable, visible, quasi-monochromatic glow of a plasma, as found in neon signs, is due to these types of excitation/de-excitation quantum mechanical processes. read more
For instance and neon plasma, like that in a neon light, is red. Also, the free electrons in the plasma can collide with ions, when that happens it can knock electrons in the ions into excited states. read more
Glow discharges are used as a source of light in devices such as neon lights, fluorescent lamps, and plasma-screen televisions. Analyzing the light produced with spectroscopy can reveal information about the atomic interactions in the gas, so glow discharges are used in plasma physics and analytical chemistry. read more