Dynamic evidence of chemical and physical traps in H-bonded confined liquids

Rayleigh wing, infrared (IR) absorption, and Raman-scattering measurements are employed to investigate the reorientational and vibrational dynamics of ethylene glycol and its homologous systems, namely ethylene glycol monomethyl ether and ethylene glycol dimethyl ether, in the bulk state and confined into 25 Angstrom pores of a sol-gel porous glass. As far as the Rayleigh wing data are concerned, the quantitative analysis of the different contributions in the spectra shows the clear influence of the physical and chemical confinement on the mobility of the studied liquids. In addition the IR and Raman measurements, performed in the O-H stretching region, allowed to identify the intramolecular, II-bond imposed, sub-band, as well as to connect the various sub-bands to different intermolecular environments originated by the existence of the II-bond potential. The observed dynamics is discussed on the basis of current theories for associated liquids. (C) 1998 American Institute of Physics. [S0021-9606(98)52041-7].