High-Pressure Raman Study of n-Octane up to 15 GPa

Pressure and Composition Effects on a Common Nanoparticle Ligand-Solvent Pair

The effect of pressure on the properties of nanoparticles is a growing area of investigation. These measurements are typically performed in a colloidal suspension; however, pressure-induced changes in the interactions between the nanoparticle surface and the solvent are often neglected. Here, we report vibrational spectroscopy of a common nanoparticle ligand, 1-dodecanethiol, and a common solvent, toluene, under pressure. We find that the pressure-induced phase change of the 1-dodecanethiol is altered by the presence of toluene and that change depends on the concentration of the free ligand in the solution. At near-equal concentrations, phase segregation is observed and the dodecanethiol crystallizes independently from the toluene. On the other hand, at unequal concentrations, concerted phase transitions are observed in the dodecanethiol and toluene, and a disordered conformation of dodecanethiol is maintained under much higher pressures. These results shed light on the pressure-induced changes in intermolecular interactions between nanoparticle ligands and solvents, which must be considered in the design of high-pressure investigations of colloidal nanoparticles.

High pressure investigations on TTF-TCNQ charge-transfer complexes

Charge-transfer complexes (CTC) exhibit promising application in scientific field. A prototype CTC (TTF-TCNQ), formed by charge donating (tetrathiafulvalene) and charge accepting (tetracyanoquinodimethane) molecule, was systematically studied by Raman method. By combining Raman and synchrony X-ray diffraction (XRD), we investigated the high-pressure structures of TTF-TCNQ up to 15 GPa, and did not observe any first-order phase transition. Finally, a detailed evolution of structure for TTF-TCNQ, versus pressure, is provided, offering a new pathway to investigate the structural stability of CTC.