Influence of the alkyl side-chain length on the ultrafast vibrational dynamics of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (CnmimNTf2) ionic liquids

Time-resolved nonlinear optical spectroscopy of perovskites

Ultrafast decay of optical phonons has been studied in wide-bandgap BaSnO3 and SrTiO3 perovskites using nonlinear spectroscopy with 120 femtosecond time resolution. The coherent Raman mode excitations have been selected and traced with tunable optical pulses. Decay of symmetry forbidden modes of vibrations have been detected directly in time. Phonon decay rates for the main LO- and TO- phonon modes have been found to be within 1.36-1.78 ps-1 and are explained in terms of parametric phonon interactions and pure dephasing mechanisms in the materials that are of interest in microelectronic applications.

Ionic liquid mixtures as energy storage materials: a preliminary and comparative study based on thermal storage density

Fifteen equimolar binary mixtures are synthesized and thermophysically evaluated in this study. These mixtures are derived from six ionic liquids (ILs) based on methylimidazolium and 2,3-dimethylimidazolium cations with butyl chains. The objective is to compare and elucidate the impact of small structural changes on the thermal properties. The preliminary results are compared to previously obtained results with mixtures containing longer eight-carbon chains. The study demonstrates that certain mixtures exhibit an increase in their heat capacity. Additionally, due to their higher densities, these mixtures achieve a thermal storage density equivalent to that of mixtures with longer chains. Moreover, their thermal storage density surpasses that of some conventional materials commonly used for energy storage.

Femtosecond coherent Raman system with >75 dB dynamic range for probing vibration modes across 250-2400 cm-1

We report on the design and performance of a time-resolved Coherent Raman spectroscopy system with time resolution of better than 120 fs. The coherent transients can be traced with more than 75 dB dynamic range while accessing and probing Raman active modes across a 250-2400 cm^-1 frequency. The system delivers an equivalent spectral resolution of better than 0.1 cm^-1 regarding line bandwidth parameters for probed Raman resonances.