Hemant K Kashyap

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In this article we show that, analyzed in a barycentric reference frame, the deviation in conductivity measured directly from impedance experiments with respect to that estimated indirectly from NMR diffusion experiments has different origins in electrolyte solutions and pure salts. In the case of electrolyte solutions, the momentum conservation law is(More)
Steady state and time-resolved fluorescence spectroscopic techniques have been used to explore the Stokes' shift dynamics and rotational relaxation of a dipolar solute probe in molten mixtures of acetamide (CH(3)CONH(2)) with sodium and potassium thiocyanates (Na /KSCN) at T approximately 318 K and several other higher temperatures. The dipolar solute probe(More)
A recently developed molecular theory is used to investigate the temperature dependence of the dynamic fluorescence Stokes shift of a dipolar solute in seven imidazolium ionic liquids. The temperature range considered is 278.15-338.15 K, for which experimental dielectric relaxation data (frequency range of 0.2 ≤ ν/GHz ≤ 89) are available. The theory used(More)
We report the combined results of computational and x ray scattering studies of amorphous methyltributylammonium bis(trifluoromethylsulfonyl)amide as a function of temperature. These studies included the temperature range for the normal isotropic liquid, a deeply supercooled liquid and the glass. The low q peaks in the range from 0.3 to 1.5 A(-1) in the(More)
In this work we compare the role that different anions play in the structure function S(q) for a set of liquids with the same cation. It is well established that because of their amphiphilic nature and their often larger size, cations play a fundamental role in the structural landscape of ionic liquids. On the other hand, it is often atoms in the anions(More)
Structural patterns that have the same spatial periodicity but a phase offset give rise to peaks and anti-peaks (negative-going peaks) at the same q value in the SAXS structure function S(q). As an example, in ionic liquids we often find charge alternation, and at the distance where one finds a density enhancement of charges of the same type one also finds(More)
The structural landscape of room-temperature ionic liquids (RTILs) with longer cationic alkyl tail(s) exhibits polarity ordering (PO) along with charge ordering (CO). In polarity ordering, which is also referred to as intermediate-range ordering, polar groups are separated by segregated domains of apolar groups and vice versa. Charge ordering resembles(More)
Solvation dynamics in four imidazolium cation based room temperature ionic liquids (RTIL) have been calculated by using the recently measured dielectric relaxation data [ J. Phys. Chem. B 2008, 112, 4854 ] as an input in a molecular hydrodynamic theory developed earlier for studying solvation energy relaxation in polar solvents. Coumarin 153 (C153),(More)
In the present molecular dynamics study, we investigate the effects of increasing pressure on the structural morphology of trihexyl(tetradecyl)phosphonium bromide (P666,14+/Br-) and trihexyl(tetradecyl)phosphonium dicyanamide (P666,14+/DCA-) ionic liquids (ILs). Special attention was paid to how charge and polarity orderings, which are present in the(More)
X-ray scattering and molecular dynamics simulations have been carried out to investigate structural differences and similarities in the condensed phase between pyrrolidinium-based ionic liquids paired with the bis(trifluoromethylsulfonyl)amide (NTf2(-)) anion where the cationic tail is linear, branched, or cyclic. This is important in light of the charge(More)