| Grant number: | 14/15049-8 |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |
| Start date: | November 01, 2014 |
| End date: | October 31, 2018 |
| Field of knowledge: | Physical Sciences and Mathematics - Chemistry - Physical-Chemistry |
| Principal Investigator: | Mauro Carlos Costa Ribeiro |
| Grantee: | Thamires Andrade Lima |
| Host Institution: | Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| Associated research grant: | 12/13119-3 - Vibrational spectroscopy in condensed phases, AP.TEM |
| Associated scholarship(s): | 16/24241-5 - Studying the dynamics of glass forming ionic liquids by neutron and X-ray scattering, BE.EP.PD |
Abstract Several room temperature molten salts, the so-called ionic liquids, are viscous liquids, which are easily supercooled with typical glass transition temperature Tg = 190 K. In the Molecular Spectroscopy Laboratory of IQ-USP, LEM/IQ-USP, we have been studying several issues on the dynamics of glass transition of ionic liquids by Raman spectroscopy as a function of temperature. In this work, we will study the glass transition at room temperature of ionic liquids under high pressure by using a diamond anvil cell (DAC) allowing for ca. 5.0 GPa of applied pressure. The relevance of pressure in studying glass-forming liquids relies on the fact that pressure addresses the role played by density, and therefore free volume, from thermal energy effects. The spectral window of interest is the low-frequency range, w < 100 cm-1, as it directly probes the intermolecular dynamics. Raman spectra within the low-frequency range result from fast (picoseconds) relaxation processes and intermolecular vibrational dynamics, the so-called boson peak. The relative contribution of relaxation and vibration exhibits remarkable temperature dependence, and in this work we intend the study of the pressure dependence. The aim of this work is to compare temperature and pressure effects, as it has been proposed that relaxation in different thermodynamic states before or after the glass transition might be determined by free volume or thermal energy. | |
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