Raman spectroscopy and molecular dynamics of ionic liquids

Abstract

This project of passage for PhD studies expands and deepens the project started on the masters, "Raman spectroscopy study of glass transition and crystallization of ionic liquids," 2010/12717-9 FAPESP process. Ionic liquids are generally viscous and easily super-cooled, so that they are precursors of glass (glass-forming liquids). In this project, we are particularly interested in ionic liquids states: supercooled liquid, glassy and crystalline. Structural aspects of different phases of these systems are being investigated by Raman spectroscopy from the differences in vibrational frequency, relative intensity and shape bandwidth between liquid and solid states resulting from the modification of the local environment experienced by the ions. In this project, the study of Raman spectra as a function of temperature will be complemented by measures of the spectra as a function of pressure. Calculations of ab initio quantum chemistry will be conducted to assist in the assignment of vibrational frequencies observed experimentally. In the PhD project, simulations of ionic liquids by the method of molecular dynamics will also be conducted to investigate the dependence of the conformation of the ions with the thermodynamic state. We will ask later Bolsa de Estágio de Pesquisa no Exterior (BEPE) to the fellow intern for about one year in the group of Prof. Edward W. Castner, Depart. of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, USA. The group of Prof. Castner have been studying the structure and dynamics of ionic liquids for spectroscopy of x-ray scattering and NMR. Therefore, by using various spectroscopic techniques and methods of calculations, the project aims to contribute to understanding the structure of ionic liquids as well as analyze the occurrence of crystallization or glass transition, the formation of the "glacial" state and the role of nucleation frustrated in the glass transition of glass-forming liquids. (AU)