Self-diffusion in liquid acetonitrile under pressure

Hurle, Robert L.; Woolf, L. A.

doi:10.1039/f19827802233

Cited by 74 publications

(35 citation statements)

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“…Using this phase cycle, the diffusion coefficient of acetonitrile at 298 K and 0.1 MPa was measured to be 3.7 × 10 −5 cm 2 /s, the same value from the first and second echo. This is within the range of reported values at these conditions which range from 3.18 × 10 −5 cm 2 /s to 4.35 × 10 −5 cm 2 /s …”

Section: Echo Superposition and Phase Cyclingsupporting

confidence: 89%

Diffusion measurements using the second echo

Fabich

Nandi

Thomann

et al. 2018

Concepts Magnetic Resonance

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We present a tutorial discussion of diffusion measurements by NMR, aimed around a specific problem. To measure diffusion in the presence of convective flow, one may use the second echo using the well‐known cancellation of phase effects from flow for the second echo. In testing this with a simple organic liquid and a static (dc) gradient at room temperature, where no convection can occur, we noticed the data from the second echo implied a substantially larger rate of diffusion than for the first echo. The error is due to the second echo being a superposition of a spin (Hahn) echo (an echo of the first echo) and a stimulated echo. We show that the stimulated echo is more attenuated by diffusion (it has a larger b value), explaining our result. A simple phase cycle is presented that suppresses the stimulated echo and leads to the correct diffusion value from the second echo. That is, the diffusion values taken from the first and second echoes are now identical.

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Section: Echo Superposition and Phase Cyclingsupporting

confidence: 89%

Diffusion measurements using the second echo

Fabich

Nandi

Thomann

et al. 2018

Concepts Magnetic Resonance

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“…The sample height was 2 mm. The diffusion coefficients were calculated using the Stejskal-Tanner diffusion equation [36], i.e., ln (I/ I 0 ) = À Dc 2 G 2 d 2 (D À d/3) only for data where the correlation coefficient of ln (I/I 0 ) versus c 2 G 2 d 2 (D À d/3) was higher than 0.99. To determine the reliable size of the random error of the spectral repetitions, a single spectrum of the solvent was chosen as a target; a more efficient way to observe the reliability of quantitative results.…”

Section: Methodsmentioning

confidence: 99%

“…In the past a significant number of the published diffusion coefficients for solvent molecules were obtained using the diaphragm and capillary-cell protocols [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39], and PFG-NMR [40][41][42][43][44][45][46][47]. However, the published values exhibit scatter and are not comparable because the first method requires tracer isotope molecules.…”

Section: Introductionmentioning

confidence: 98%

Assessment of diffusion coefficients of general solvents by PFG-NMR: Investigation of the sources error

Kato

Saito

Nabeshima

et al. 2006

Journal of Magnetic Resonance

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“…Because the temperature dependence of the self-diffusion coefficients of these two compounds is known [57,58], their measured D values were then corrected in accordance with the true sample temperature. The results are reported in Fig.…”

Section: Influence Of Mas On Diffusion Measurementsmentioning

confidence: 99%

Pulsed field gradient magic angle spinning NMR self-diffusion measurements in liquids

Viel

Ziarelli

Pagès

et al. 2008

Journal of Magnetic Resonance

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Several investigations have recently reported the combined use of pulsed field gradient (PFG) with magic angle spinning (MAS) for the analysis of molecular mobility in heterogeneous materials. In contrast, little attention has been devoted so far to delimiting the role of the extra force field induced by sample rotation on the significance and reliability of self-diffusivity measurements. The main purpose of this work is to examine this phenomenon by focusing on pure liquids for which its impact is expected to be largest. Specifically, we show that self-diffusion coefficients can be accurately determined by PFG MAS NMR diffusion measurements in liquids, provided that specific experimental conditions are met. First, the methodology to estimate the gradient uniformity and to properly calibrate its absolute strength is briefly reviewed and applied on a MAS probe equipped with a gradient coil aligned along the rotor spinning axis, the so-called 'magic angle gradient' coil. Second, the influence of MAS on the outcome of PFG MAS diffusion measurements in liquids is investigated for two distinct typical rotors of different active volumes, 12 and 50 microL. While the latter rotor led to totally unreliable results, especially for low viscosity compounds, the former allowed for the determination of accurate self-diffusion coefficients both for fast and slowly diffusing species. Potential implications of this work are the possibility to measure accurate self-diffusion coefficients of sample-limited mixtures or to avoid radiation damping interferences in NMR diffusion measurements. Overall, the outlined methodology should be of interest to anyone who strives to improve the reliability of MAS diffusion studies, both in homogeneous and heterogeneous media.

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Self-diffusion in liquid acetonitrile under pressure

Cited by 74 publications

References 0 publications

Diffusion measurements using the second echo

Diffusion measurements using the second echo

Assessment of diffusion coefficients of general solvents by PFG-NMR: Investigation of the sources error

Pulsed field gradient magic angle spinning NMR self-diffusion measurements in liquids

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