Presentation Title

Water dynamics in CaSO4.2D2O investigated by deuterium nuclear magnetic resonance

Faculty Mentor

Dr. Deniz Cizmeciyan

Start Date

17-11-2018 12:30 PM

End Date

17-11-2018 2:30 PM

Location

CREVELING 112

Session

POSTER 2

Type of Presentation

Poster

Subject Area

physical_mathematical_sciences

Abstract

Deuterium with a spin quantum of one, has a non-spherically symmetrical nuclear charge distribution. It possesses a quadrupole moment that interacts with the electrical field gradients around the nucleus giving rise to a quadrupolar interaction, which dominates its solid state NMR spectrum. Deuterium line shapes are very sensitive to molecular motion and provide valuable information through line shape simulations. We are investigating the molecular motion of D2O in perdeuterated Gypsum using variable temperature deuterium NMR line shape analysis and deuterium T1 relaxation time simulations. At 295K the results indicate that the deuterium nuclei of D2O in Gypsum undergo two-site C2180 degree jumps about the D-O-D bisector angle of 54.80 at a rate of >107sec-1. The jump rate stays in the fast motion regime down to 198K. At 198K and 173K the motion is in the intermediate motion regime where the line intensities drop and k varies from 1x106 to 5x105s-1. The best fit quadrupole coupling constants for the range of temperatures (qcc’s) vary between 216 kHz and 235kHz and the asymmetry parameters between 0.10 to 0.15. We calculated activation parameters of ΔH= 15.12kJ/mol, and ΔS= -42.30 J/mol.K and an activation energy of Ea= 16.93 kJ/mol for the C2 jumps.

Summary of research results to be presented

Up to -50oC D2O rotates around its C2 axis in the fast motion regime (>107 Hz) and η deviated form the typical zero.

At -75oC and -100oC this motion is in the intermediate motion regime. T1 simulation is necessary as line intensity drops in the experimental spectra.

The activation parameters obtained are 13.114 kJ/mol for Ea, 11.232 kJ/mol for ∆H+, and -71 J/(K*mol) for ∆S+.

This document is currently not available here.

Share

COinS
 
Nov 17th, 12:30 PM Nov 17th, 2:30 PM

Water dynamics in CaSO4.2D2O investigated by deuterium nuclear magnetic resonance

CREVELING 112

Deuterium with a spin quantum of one, has a non-spherically symmetrical nuclear charge distribution. It possesses a quadrupole moment that interacts with the electrical field gradients around the nucleus giving rise to a quadrupolar interaction, which dominates its solid state NMR spectrum. Deuterium line shapes are very sensitive to molecular motion and provide valuable information through line shape simulations. We are investigating the molecular motion of D2O in perdeuterated Gypsum using variable temperature deuterium NMR line shape analysis and deuterium T1 relaxation time simulations. At 295K the results indicate that the deuterium nuclei of D2O in Gypsum undergo two-site C2180 degree jumps about the D-O-D bisector angle of 54.80 at a rate of >107sec-1. The jump rate stays in the fast motion regime down to 198K. At 198K and 173K the motion is in the intermediate motion regime where the line intensities drop and k varies from 1x106 to 5x105s-1. The best fit quadrupole coupling constants for the range of temperatures (qcc’s) vary between 216 kHz and 235kHz and the asymmetry parameters between 0.10 to 0.15. We calculated activation parameters of ΔH= 15.12kJ/mol, and ΔS= -42.30 J/mol.K and an activation energy of Ea= 16.93 kJ/mol for the C2 jumps.