Intermolecular Vibrations in Aprotic Molecular Liquids and Ionic Liquids

Physical Properties and Low-Frequency Polarizability Anisotropy and Dipole Responses of Phosphonium Bis(fluorosulfonyl)amide Ionic Liquids with Pentyl, Ethoxyethyl, or 2-(Ethylthio)ethyl Group

“…First, the surface tensions of the [P 2225 ][NF 2 ] and [P 222(2O2) ][NF 2 ] were almost the same. We previously reported that the surface tension of ( 2 35.0 mN m −1 ) was higher than that of triethyloctylphosphonium bis(trifluorometylsulfonyl)amide ([P 2228 ][NTf 2 ], 32.7 mN m −1 ). 15 This feature is also true for the respective ammonium-based ILs.…”

“…This study directly compared the essential physical properties, such as glass transition temperature, viscosity, density, surface tension, and electrical conductivity, and the low-frequency spectra of triethylpentylphosphonium bis­(fluorosulfonyl)­amide ([P 2225 ]­[NF 2 ]), ethoxyethyltriethylphosphonium bis­(fluorosulfonyl)­amide ([P 222(2O2) ]­[NF 2 ]), and triethyl­[2-(ethylthio)­ethyl]­phosphonium bis­(fluorosulfonyl)­amide ([P 222(2S2) ]­[NF 2 ]) at various temperatures using femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES) − and terahertz time-domain spectroscopy (THz-TDS). , The low-frequency vibrations in ILs were investigated using both the time-domain vibrational techniques, fs-RIKES ,− and THz-TDS, − and frequency domain methods − to date. Some studies have compared the low-frequency spectra of ILs using fs-RIKES and THz-TDS (and dielectric relaxation) − or Raman and IR spectroscopy, although the main focus is the collective orientational relaxation and the number of reports is few.…”

Exploring the Microscopic Aspects of 1-Methyl-3-octylimidazolium Tetrafluoroborate Mixtures with Formamide, N-Methylformamide, and N,N-Dimethylformamide by Multiple Spectroscopic Techniques and Computations

“…A multiple spectroscopic technique is helpful to understand the molecular-level aspects of IL mixtures from various perspectives. , For example, the situation of a specific nuclei can be elucidated by NMR. − Observations of the unique intramolecular vibrational modes (typically over 800 cm –1 ) by IR and Raman spectroscopies reveal the specific interactions of functional groups in the targets. − The intermolecular vibrational band that appears in the low-frequency region below 200 cm –1 can be detected by femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES) − and terahertz time-domain spectroscopy, , which are complementary spectroscopic methods to observe Raman- and IR-active motions in the low-frequency region and probe the microscopic intermolecular interaction and structure in liquids − including ILs. − The direct measurement of intermolecular vibrational spectra is significant because the intermolecular interactions affecting the liquid properties of ILs and their mixtures must be determined to tune these liquid properties . Frequency-domain Raman and far-IR spectroscopies have also been applied for several ILs. ,, Intermolecular vibrations are often treated as fluctuations in liquids and solutions from a dynamical aspect.…”

“…36−53 The direct measurement of intermolecular vibrational spectra is significant because the intermolecular interactions affecting the liquid properties of ILs and their mixtures must be determined to tune these liquid properties. 23 Frequency-domain Raman and far-IR spectroscopies have also been applied for several ILs. 20,54,55 Intermolecular vibrations are often treated as fluctuations in liquids and solutions from a dynamical aspect.…”

Intermolecular Dynamics of Positively and Negatively Charged Aromatics and Their Isoelectronic Neutral Analogs in Aqueous Solutions

“…Femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES) is a powerful technique for the investigation of the low-frequency molecular motions (dynamical fluctuation) due to interaction- or collision-induced motion, libration, and the overdamped relaxation process in liquids and solutions. − The fs-RIKES technique is a time-domain Raman spectroscopy. In contrast to the steady-state Raman spectroscopy (wavelength dispersive spectroscopy), fs-RIKES simultaneously detects both Stokes and anti-Stokes signals because the Raman active modes at various vibrational states are induced within a spectral width of a femtosecond pump pulse.…”