Infrared spectra are reported for carbon dioxide and nitrous oxide solvated in superfluid helium droplets, corresponding to the vibrational excitation of the (02(0)1)/(10(0)1) Fermi diad. Although the rotational constants of these two molecules are similar in the gas phase, they are observed to be quite different in liquid helium, namely, 0.154 cm(-1) for CO2 and 0.0717 cm(-1) for N2O. In addition, solvation in helium results in shifts in the vibrational origin that are in the opposite directions, -0.42 cm(-1), for CO2 and +1.2 cm(-1) for N2O. The spectra also show strong droplet size dependence, indicative of the interactions between the molecule and the liquid.