NEGATIVE EFFECTIVE PRESSURES IN LIQUID MIXTURES

Abstract

Ethanol was studied under hydrostatic pressure and in mixtures with water and with chloroform. High resolution Raman spectroscopy was used to monitor the change in vibrational frequency as a function of pressure and composition. Molecular dynamics (MD) simulations were carried out and were compared with experimental results. Results show that for mixtures the cohesive energy density (CED) acts like a real pressure. The CED of a mixture is different from the CED's of the components, and the differences result in effective pressures, negative and positive, on the components of the mixture. Other strong effects overshadow the working of this pressure in some cases. Nevertheless, it is possible to generate an effective negative pressure, which will have various applications in for example protein folding.

Keywords:

• Negative pressure
• Cohesive energy density
• Liquid mixtures
• Raman
• Ethanol