Ultra-Broadband Dielectric and Optical Kerr-Effect Study of the Ionic Liquids Ethyl and Propylammonium Nitrate

Sonnleitner, Thomas; Turton, David A.; Hefter, Glenn; Ortner, Alexander; Waselikowski, Stefan; Walther, Markus; Wynne, Klaas; Buchner, Richard

doi:10.1021/jp502935t

Cited by 52 publications

(47 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the slope of t 1 vs. Z a friction coefficient of C = 0.127 can be calculated, which is close to that of neat EAN (C = 0.091), obtained from temperature-dependent measurements. 56 This implies that the dynamical properties of pure EAN are preserved down to a dilution of x EAN E 0.5 (Fig. 6a) and suggests that AN acts as a ''lubricant'' accelerating the overall dynamics, similar to what was found for 1-alkyl-3-methylimidazolium IL + AN mixtures.…”

Section: Amplitudessupporting

confidence: 58%

Do H-bonds explain strong ion aggregation in ethylammonium nitrate + acetonitrile mixtures?

Sonnleitner

Nikitina

Nazet

et al. 2013

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

Binary mixtures of the protic ionic liquid ethylammonium nitrate (EAN) and acetonitrile (AN) were studied at 25 1C over the entire composition range by means of broadband dielectric spectroscopy covering 0.2 r n/GHz r 89. The dielectric spectra could be decomposed into two relaxation processes, both of which proved to be composite modes. For dilute solutions the higher-frequency Debye relaxation centered at B60 GHz is associated with the rotational diffusion of AN molecules, whereas at higher salt concentrations ultra-fast intermolecular vibrations and librations of EAN dominate the process. For EAN-rich solutions the lower-frequency relaxation is mainly due to jump reorientation of the ethylammonium cation, whereas contact ion pairs (CIPs) dominate this mode for dilute solutions. From the relaxation amplitudes effective solvation numbers and ion-pair concentrations were determined. For vanishing EAN mole fraction, x EAN -0, an effective cation solvation number of B7 was found which steeply drops until x EAN E 0.2 but shows only moderate decrease later on. The obtained association constant for EAN, K 0 A = 970 L mol À1 , exceeds that of other 1 : 1 electrolytes in AN by a factor of B30-50. This observation, as well as the fact that CIPs are formed despite strong cation solvation, indicates that ion pairing is mainly driven by the formation of strong hydrogen bonds between anions and cations.

show abstract

Section: Amplitudessupporting

confidence: 58%

Do H-bonds explain strong ion aggregation in ethylammonium nitrate + acetonitrile mixtures?

Sonnleitner

Nikitina

Nazet

et al. 2013

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…As found previously [32], the use of a G instead of a DHO bandshape for the highest-frequency mode provided a better description of ε′(ν) and ε′′(ν) at ν N 2 THz. Other tested fit models, based on combinations of up to four relaxation and/or resonance modes, yielded larger χ r 2 values or did not converge.…”

Section: Discussionsupporting

confidence: 65%

“…The libration and intermolecular vibration modes present in this region are of resonant character. Such band shapes can be modelled by damped harmonic oscillators (DHO) or antisymmetrized Gaussian oscillators (G) [32]. Additionally, relaxation modes extending into the THz region require a high-frequency correction to allow for molecular inertia [33].…”

Section: Discussionmentioning

confidence: 99%

Dielectric response and collective dynamics of acetonitrile

Stoppa

Nazet

Buchner

et al. 2015

Journal of Molecular Liquids

Self Cite

View full text Add to dashboard Cite

“…The loss function χ ′′ X (ω) is broadly distributed, in accord with the highly stretched dielectric relaxation of RTILs. 40,82 Two characteristic peaks, at sub-picosecond and nanosecond range of frequencies, mirror the corresponding peaks in the dielectric loss functions. Integration of χ ′′ X (ω) in Eq.…”

Section: Electrode Reactions In Ionic Liquidsmentioning

confidence: 78%

Electrode reactions in slowly relaxing media

Matyushov

Newton

2017

The Journal of Chemical Physics

View full text Add to dashboard Cite

Standard models of reaction kinetics in condensed materials rely on the Boltzmann-Gibbs distribution for the population of reactants at the top of the free energy barrier separating them from the products. While energy dissipation and quantum effects at the barrier top can potentially affect the transmission coefficient entering the rate pre-exponential factor, much stronger dynamical effects on the reaction barrier are caused by the breakdown of ergodicity for populating the reaction barrier (violation of the Boltzmann-Gibbs statistics). When the spectrum of medium modes coupled to the reaction coordinate includes fluctuations slower than the reaction rate, such nuclear motions dynamically freeze on the reaction time scale and do not contribute to the activation barrier. Here we consider the consequences of this scenario for electrode reactions in slowly relaxing media. Changing the electrode overpotential speeds the electrode electron transfer up, potentially cutting through the spectrum of nuclear modes coupled to the reaction coordinate. The reorganization energy of electrochemical electron transfer becomes a function of the electrode overpotential, switching between the thermodynamic value at low rates to the nonergodic limit at higher rates. The sharpness of this transition depends on the relaxation spectrum of the medium. The reorganization energy experiences a sudden drop with increasing overpotential for a medium with a Debye relaxation but becomes a much shallower function of the overpotential for media with stretched exponential dynamics. The latter scenario characterizes the electron transfer in ionic liquids. The analysis of electrode reactions in room-temperature ionic liquids shows that the magnitude of the free energy of nuclear solvation is significantly below its thermodynamic limit. This result applies to reaction times faster than microseconds and is currently limited by the available dielectric relaxation data.

show abstract

Ultra-Broadband Dielectric and Optical Kerr-Effect Study of the Ionic Liquids Ethyl and Propylammonium Nitrate

Cited by 52 publications

References 80 publications

Do H-bonds explain strong ion aggregation in ethylammonium nitrate + acetonitrile mixtures?

Do H-bonds explain strong ion aggregation in ethylammonium nitrate + acetonitrile mixtures?

Dielectric response and collective dynamics of acetonitrile

Electrode reactions in slowly relaxing media

Contact Info

Product

Resources

About