ИСТИНА

Nanoporous materials and composite structures based on them have occupied a wide niche in modern science and technological applications such as refining, cleaning, catalysis, storage, biological and chemical sensing. Phase behavior of molecular fluids in pores is of considerable interest. Nanoconfined geometry, effective interaction with pore walls define essential features of fluid state in nanopores in comparison with ones in the bulk volume. The sensitive and high-resolution methods of immediate control and diagnostics of a molecular media inside nanocomposite system allowing to probe its phase composition, fragmentation features, interaction with the pore walls and with nanoparticles within the pores are to be developed. Coherent anti-Stokes Raman scattering (CARS) can be efficiently used for diagnostics of fluid phase behavior in nanopores with diameter of several nanometers including the case of near-critical temperatures. In the present work, CARS spectroscopy is applied to analyze the vibrational spectra of carbon dioxide in the depth of nanoporous Vycor glass samples with pores of about 2 nm radius. Similarly, we tested the samples with silver nanoparticles inside pores introduced by means the impregnation the sample with the silver-containing precursor and the following thermo-chemical processing. The size and shape of nanoparticles within nanopores can be monitored through observation the extinction spectrum of the samples. For better sensitivity and high spatial resolution of CARS measurements, we used noncollinear technique. This allowed observation of molecular adsorbed layers on pore walls in the depth of the glass samples beginning from pressure values of several atm that is well before the saturation pressure in the pore volume. The nature of substantially inhomogeneous spectral broadening and manifestation of nanoparticles in CARS spectra will be discussed.