A1 Refereed original research article in a scientific journal
Separation of the ortho and para NMR signals in solid deuterium via DQ filtering
Authors: Malmi P, Punkkinen M, Ylinen E, Shevtsov V
Publisher: ACADEMIC PRESS INC
Publication year: 2000
Journal:: Journal of Magnetic Resonance
Journal name in source: JOURNAL OF MAGNETIC RESONANCE
Journal acronym: J MAGN RESON
Volume: 145
Issue: 2
First page : 326
Last page: 333
Number of pages: 8
ISSN: 1090-7807
DOI: https://doi.org/10.1006/jmre.2000.2094
Abstract
Double quantum (DQ) filtering is shown to lead to an effective separation of the NMR signals from the para (I = 1) and ortho (I = 2) molecules in solid deuterium. The separation is achieved by the pulse sequence 90(phi)degrees-t(pr)-90(phi)degrees-t(ev)-90(x)degrees-t, where the phase-cycled first two pulses create the Do coherence. Two components are observed after the third pulse; the para signal shows the maximum at a short time t while the ortho signal reaches the maximum at a longer t. The observed signal can be expressed as 1/2 Sigma(I) [F-1(t(pr) - t) - F-1(t(pr) + t)], where F-1(t) is a proper fitting function for the free induction signal of the para and ortho molecules (with I = 1 or 2, respectively). Numerical fits to experimental data at 4.2 and 2 K show that this method can be used to determine the ratio F-1(0)/F-2(0) and thus, because the initial value F-1(0) is proportional to the respective magnetization before the pulse sequence, the ortho and para concentrations in solid deuterium. (C) 2000 Academic Press.
Double quantum (DQ) filtering is shown to lead to an effective separation of the NMR signals from the para (I = 1) and ortho (I = 2) molecules in solid deuterium. The separation is achieved by the pulse sequence 90(phi)degrees-t(pr)-90(phi)degrees-t(ev)-90(x)degrees-t, where the phase-cycled first two pulses create the Do coherence. Two components are observed after the third pulse; the para signal shows the maximum at a short time t while the ortho signal reaches the maximum at a longer t. The observed signal can be expressed as 1/2 Sigma(I) [F-1(t(pr) - t) - F-1(t(pr) + t)], where F-1(t) is a proper fitting function for the free induction signal of the para and ortho molecules (with I = 1 or 2, respectively). Numerical fits to experimental data at 4.2 and 2 K show that this method can be used to determine the ratio F-1(0)/F-2(0) and thus, because the initial value F-1(0) is proportional to the respective magnetization before the pulse sequence, the ortho and para concentrations in solid deuterium. (C) 2000 Academic Press.
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