Spectroscopic evidence of reversible micro-crystallization of carbon dioxide dissolved in solid xenon

FTIR spectra of CO2 dissolved in liquid and solid Xe have been studied in ∼1000 ÷ 6000 cm−1 frequency domain at T ∼ 170 ÷ 100 K. Apart a set of the fundamental and combination bands of the solute CO2, a set of new bands ascribed to crystalline CO2 have been found in the solid species. The crystallization process is reversible with respect to temperature variations. The qualitative change of the intensity ratio between the low-and high frequency components of the Fermi resonance Πu doublet (1110)I/(1110)II has been revealed for the crystalline CO2.