  A Monte Carlo model has been developed to study the degradation of <1000 eV
electrons in an atmosphere of CO2, which is one of the most abundant species in
Mars' and Venus' atmospheres. The e-CO2 cross sections are presented in an
assembled set along with their analytical representations. Monte Carlo
simulations are carried out at several energies to calculate the "yield
spectra", which embodied all the information related to electron degradation
process and can be used to calculate "yield" (or population) for any inelastic
process. The numerical yield spectra have been fitted analytically resulting in
an analytical yield spectra (AYS). We have calculated the mean energy per ion
pair and efficiencies for various inelastic processes, including the double and
dissociative double ionization of \car\ and negative ion formation. The energy
distribution of the secondary electrons produced per incident electron is also
presented at few incident energies. The mean energy per ion pair for CO2 is
37.5 (35.8) eV at 200 (1000) eV, compared to experimental value 32.7 eV at high
energies. Ionization is the dominant loss process at energies above 50 eV with
contribution of ~50%. Among the excitation processes, 13.6 eV and 12.4 eV
states are the dominant loss processes consuming ~28% energy above 200 eV.
Around and below ionization threshold, 13.6 eV, 12.4 eV, and 11.1 eV, followed
by 8.6 eV and 9.3 eV excitation states are important loss processes, while
below 10 eV vibrational excitation dominates.
