What kind of radiation (light) does CO2 molecule absorb -UV or IR? I've read that it's infrared however some sources suggest ultraviolet. If so, how might it be possible?
It is tedious trying to get good answers to this by searching the net because the first large-patience-testing-number of hits are likely to be advocacy web sites. Sigh. Even if what they are advocating is correct it is tedious.
CO2 is a linear molecule in the form O-C-O, so it has no dipole. So it will need particular energy ranges to strongly absorb. But it can have different ranges that it strongly absorbs.
Essentially, these will be the energies that can interact with transitions the molecule can make. These will primarily include rotational and vibrational modes. Eventually at high enough energy you will start to get into energy ranges that can split an O off the molecule.
Here is the spectrum of solar radiation from wikipedia, where also the absorption by CO2 is shown , where it diminishes the radiation:
The wavelengths of CO2 absorption are larger than 2000 nanometers, i.e larger than microns. UV is order of 0.1micron . It may be possible if one is lenient with the limits of definition that some ultraviolet absorption by CO2 may happen, but should not be significant.