CONFINEMENT EFFECTS ON THE DYNAMICS OF LIQUID CARBON-DISULFIDE

The effects of confinement on the dynamics of liquid CS2 were studied by spontaneous Raman spectroscopy The Raman bands of the fundamental symmetric stretching mode, nu(1) (similar to 655 cm(-1)), and the first overtone, 2 nu(2) (similar to 800 cm(-1)), of liquid CS2 confined to porous sol-gel silica glasses with pore radii in the range from 12 to 50 Angstrom were investigated at 20 degrees C. In contrast to earlier literature reports, the confinement affects the dynamics of the confined liquid CS2 in a major way. The experimental data allowed us to determine the effects of confinement on the vibrational and reorientational correlation functions, the Fermi resonance strength S, and the anharmonic force constant K-122 The decreasing pore size leads to a decrease in the vibrational dephasing time and an increase in the reorientational correlation time. It is interesting to find that the correlation times scale with the pore size as 1/R (R is the pore radius). The similarities in the confinement effects and the effects produced by high pressure on the dynamics of bulk liquid CS2 are discussed in a phenomenological way. Both the decrease of S and K-122 With decreasing pore size (scaling as 1/R) can be qualitatively interpreted in terms of increased orientational order of the confined CS2.