Acoustic, thermal and flow processes in a water filled nanoporous glass by time-resolved optical spectroscopy
Year: 2010
Authors: Cucini R., Taschin A., Bartolini P., Torre R.
Autors Affiliation: Univ Florence, European Lab Nonlinear Spect LENS, I-50019 Florence, Italy; Univ Florence, Dip Fis, I-50019 Florence, Italy.
Abstract: We present heterodyne detected transient grating measurements on water filled Vycor 7930 in the range of temperature 20-90 degrees C. This experimental investigation enables to measure the acoustic propagation, the average density variation due to the liquid flow and the thermal diffusion in this water filled nano-porous material. The data have been analyzed with the model of Pecker and Deresiewicz which is an extension of Biot model to account for the thermal effects. In the whole temperature range the data are qualitatively described by this hydrodynamic model that enables a meaningful insight of the different dynamic phenomena. The data analysis proves that the signal in the intermediate and long time-scale can be mainly addressed to the water dynamics inside the pores. We proved the existence of a peculiar interplay between the mass and the heat transport that produces a flow and back-flow process inside the nano-pores. During this process the solid and liquid dynamics have opposite phase as predicted by the Biot theory for the slow diffusive wave. Nevertheless, our experimental results confirm that transport of elastic energy (i.e. acoustic propagation), heat (i.e. thermal diffusion) and mass (i.e. liquid flow) in a liquid filled porous glass can be described according to hydrodynamic laws in spite of nanometric dimension of the pores. The data fitting, based on the hydrodynamic model, enables the extraction of several parameters of the water-Vycor system, even if some discrepancies appear when they are compared with values reported in the literature.
Journal/Review: JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
Volume: 58 (9) Pages from: 1302 to: 1317
More Information: The research has been performed at LENS of University of Firenze. We thank D.L. Johnson for the helpful suggestions and discussions. The research has been supported by the EC Grant no. RII3-CT-2003-506350, by CRS-INFM-Soft Matter (CNR) and MIUR-COFIN-2005 Grant no. 2005023141-003.KeyWords: Transient grating experiment; Porous media; Confined water; Acoustic wavesDOI: 10.1016/j.jmps.2010.06.002Citations: 16data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2024-10-20References taken from IsiWeb of Knowledge: (subscribers only)