ИСТИНА

Adsorption behavior of carbon dioxide in nanoporous Vycor glass was studied by coherent anti-Stokes Raman scattering spectroscopy. The intensity and profile of the CO2 band at 1388 cm-1 were measured in a wide pressure range providing the transition from partial surface coverage of the pore walls up to complete condensation in the pore volume. The contributions of the gaseous, surface-adsorbed, and liquid-like carbon dioxide have been distinguished in the spectrum even when the three states coexist. The results show that the liquid-like phase appears when the amount of the surface adsorbed fluid is below the monolayer coverage. Developed approach is applicable to characterize the fluid behavior in the pores of transparent nanoporous materials with various pore size, shape, ordering, and interconnection.