Behavior of aqueous Tetrabutylammonium bromide - a combined approach of microscopic simulation and neutron scattering

Abstract

Aqueous solution of tetrabutylammonium bromide is studied by quasi-elastic neutron scattering, to give information on the dynamic modes involving the ions present. Using a careful combination of two techniques, time-of-flight (TOF) and neutron spin echo (NSE), we decouple the dynamic information in both the coherently and incoherently scattered signal from this system. We take advantage of the different intensity ratio of the two signals, as detected by each of the techniques, to achieve this decoupling. By using heavy water as the solvent, the tetrabutylammonium cation is the only hydrogen-containing species in the system and gives rise to a significant incoherent scattered intensity. The dynamic analysis of the incoherent signal (measured by TOF) leads to a translational diffusion coefficient of the cation as that is in good agreement with previous NMR, neutron scattering and tracer diffusion measurements. The dynamic analysis of the coherent signal observed at wave-vectors < 0.6 Å−1 (measured by NSE) leads to a significantly slower diffusive mode, by a factor of 2. This study explains that apparent difference and the reasons for that.

A comparative study of solvent dynamics in Choline Bromide aqueous solution using combination of neutron scattering technique and molecular dynamics simulation

“…The Time of Flight (ToF) technique is used for the neutron scattering experiments. The details or related information could be found in ref [14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. For the experiments 0.2 mm thick flat quartz cell is used in the MIBEMOL spectrometer in LLB-Orphee reactor with resolution of 50 µeV (HWHM) under 6 Åincident beam.…”

Deep diving into the comparative study of Choline dynamics using molecular dynamics simulation and neutron scattering technique

“…The study on the dynamics will be performed by a combination of Time-of-Flight (TOF), Neutron Spin Echo (NSE) and Molecular Dynamics (MD) simulation methods [14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. We take advantage of the above mentioned techniques to study separately the coherent and incoherent signal dynamics and will find out if the two approaches (coherent and incoherent signal dynamics) lead to two different results in comparison to with MD simulation.…”