Photochemical smog

Physical and chemical properties
Carbon monoxide (CO) is a tasteless, odorless, colorless, noncorrosive and quite
stable diatomic molecule that exists as a gas in the Earth’s atmosphere. Radiation
in the visibleand near-ultraviolet (UV) regions of the electromagnetic spectrum is
not absorbed by carbon monoxide, although the molecule does have weak
absorption bands between 125 and 155 nm. Carbon monoxide absorbs radiation
in the infrared region corresponding to the vibrational excitation of its electronic
ground state.