Carbon dioxide CO2 is a linear molecule with a carbon atom in the center and two oxygen atoms on either side. There are three fundamental molecular vibrations in CO2, which can be classified as follows:1. Symmetric Stretching v1 : In this mode, both oxygen atoms move away from or towards the central carbon atom simultaneously, while the carbon atom remains stationary. This vibration is symmetric and does not result in a change in the molecule's dipole moment. As a result, it is not infrared IR active and does not contribute to the infrared spectrum of CO2.2. Bending v2 : In this mode, the molecule bends in a plane, with the carbon atom acting as the pivot point and the two oxygen atoms moving in opposite directions. This vibration is degenerate, meaning it has two equivalent forms: bending in the plane scissoring and bending out of the plane rocking . Both forms result in a change in the molecule's dipole moment, making them IR active and contributing to the infrared spectrum of CO2.3. Asymmetric Stretching v3 : In this mode, one oxygen atom moves away from the carbon atom while the other moves towards it, resulting in an asymmetric stretching motion. This vibration leads to a change in the molecule's dipole moment and is IR active, contributing to the infrared spectrum of CO2.In summary, the molecular vibrations of carbon dioxide include symmetric stretching v1 , bending v2 , and asymmetric stretching v3 . The bending and asymmetric stretching vibrations are IR active and contribute to the infrared spectrum of CO2, while the symmetric stretching vibration does not. These IR-active vibrations play a significant role in the greenhouse effect, as they absorb and re-emit infrared radiation, trapping heat in the Earth's atmosphere.