Infrared and Raman spectra of carbon dioxide monomers and dimers trapped in various matrices and in the gas phase are considered in an attempt to retrieve general regularities in vibrational shifts vs matrix properties. It is demonstrated that some useful conclusions can be drawn from an examination of the vibrational shifts as a function of the Square root of the matrix material critical temperature. These correlations can be employed to roughly predict the positions of yet unknown vibrational origins or to obtain information on the nature of optically inactive hosts.