TY - JOUR A2 - Zhang, Fajun AU - Palumbo, Oriele AU - Trequattrini, Francesco AU - Vitucci, Francesco Maria AU - Navarra, Maria Assunta AU - Panero, Stefania AU - Paolone, Annalisa PY - 2015 DA - 2015/08/30 TI - An Infrared Spectroscopy Study of the Conformational Evolution of the Bis(trifluoromethanesulfonyl)imide Ion in the Liquid and in the Glass State SP - 176067 VL - 2015 AB - We measure the far-infrared spectrum of N,N-Dimethyl-N-ethyl-N-benzylammonium (DEBA) bis(trifluoromethanesulfonyl)imide (TFSI) ionic liquid (IL) in the temperature range between 160 and 307 K. Differential scanning calorimetry measurements indicate that such IL undergoes a glass transition around 210 K. DFT calculations allow us to assign all the experimental absorptions to specific vibrations of the DEBA cation or of the two conformers of the TFSI anion. We find that the vibration frequencies calculated by means of the PBE0 functional are in better agreement with the experimental ones than those calculated at the B3LYP level, largely used for the attribution of vibration lines of ionic liquids. Experimentally we show that, in the liquid state, the relative concentrations of the two conformers of TFSI depend on temperature through the Boltzmann factor and the energy separation, ΔH, is found to be 2 kJ/mol, in agreement with previous calculations and literature. However, in the glassy state, the concentrations of the cis-TFSI and trans-TFSI remain fixed, witnessing the frozen state of this phase. SN - 1687-8108 UR - https://doi.org/10.1155/2015/176067 DO - 10.1155/2015/176067 JF - Advances in Condensed Matter Physics PB - Hindawi Publishing Corporation KW - ER -