Greenhouse gases absorb and emit energy mainly in which part of the spectrum?

Greenhouse gases absorb and emit energy mainly in the thermal infrared part of the electromagnetic spectrum.

Earth’s surface absorbs much of the Sun’s incoming energy and reradiates that energy upward as infrared radiation, because the relatively cool planet emits at longer wavelengths than the Sun. Molecules such as carbon dioxide, methane, water vapor, and nitrous oxide can absorb some of these infrared wavelengths and later emit infrared radiation in different directions.

This does not mean greenhouse gases block all sunlight. Visible light passes through the atmosphere relatively well, allowing solar energy to warm the surface. The greenhouse effect occurs mainly because the atmosphere partially slows the escape of the surface’s outgoing thermal radiation to space.

Gamma rays and ultraviolet radiation are different parts of the spectrum and are not the main band involved in the ordinary terrestrial greenhouse effect. Nitrogen and oxygen, which make up most of dry air, are poor absorbers of thermal infrared because their symmetrical molecules do not strongly interact with those wavelengths. Small concentrations of infrared-active gases can therefore have a large climatic effect.