Carbon dioxide is a linear triatomic molecule. Its importance in nature makes knowledge of it manditory. In the planetary evolution of earth, carbon dioxide has been, along with water and some simple organic molecule like methane, a natural product. Carbon dioxide is one of the stable combustion products, along with water, from burning hydrocarbons. It thus contributes to the greenhouse effect-the trapping of heat within the "atmospheric cover" of carbon dioxide. The absorbtion of heat radiation is through the vibrations of the molecule. With 3 atoms in a linear molecule there are 3N - 5 natural vibrations. These are shown in the figures below. Each vibration absorbs a different frequency of infrared radiation (heat radiation) excepting that the last two pictured are the same.

Super Critical Carbon Dioxide