مونوکسید ِ کربون
monoksid-e karbon (#)
Fr.: monoxyde de carbone
A colorless, odorless, very poisonous gas which burns in air with a
bright blue flame to form → carbon dioxide.
CO gives rise to a violent explosion when ignited in air in certain proportions. It
occurs in coal gas and in the exhaust fumes of motor engines. Melting point -207 °C;
boiling point -191.1 °C.
Carbon monoxide is the most important → molecule
found in the → interstellar medium, and is produced
through several chemical reactions, → CO formation.
It was discovered in 1970 by R. Wilson
and A. Penzias of Bell Laboratories, using the 11-m telescope of the National Radio Astronomy
Observatory (NRAO) in the direction of the → Orion nebula.
Because the CO line is so intense and widely distributed in space, this
molecule is a most useful tool for tracing the ISM. In addition,
measurement of its rare isotopes have shown that the main line
12C16O (wavelength 2.6 mm, 115 GHz) is
→ optically thick, that is the
→ column density of the molecule is so high that the
material becomes opaque at the transition frequency. Moreover, the
upper-energy levels of the CO molecule are easily excited by collision
with → molecular hydrogen.
The combination of high → optical depth
and the ease of → excitation
imply that CO emission brightness will
accurately reflect the local gas temperature. CO is also one of the
principal molecules detected in → comet
→ carbon; → mono-;