Deuteron quadrupole resonance studies. Part 9.—1H/2H double resonance in potassium bicarbonate

1979 ◽  
Vol 75 (0) ◽  
pp. 1054-1063 ◽  
Author(s):  
Ian J. F. Poplett ◽  
John A. S. Smith
Keyword(s):  
Double Resonance ◽  
Potassium Bicarbonate ◽  
Quadrupole Resonance

Double Resonance Detection Using Zero Field Level Crossing

1998 ◽  
Vol 53 (6-7) ◽  
pp. 301-304
Author(s):  
David Stephenson ◽  
John A. S. Smith
Keyword(s):  
High Frequency ◽  
Asymmetry Parameter ◽  
Double Resonance ◽  
Zero Field ◽  
Level Crossing ◽  
Small Magnetic Field ◽  
Crossing Experiment ◽  
Quadrupole Resonance ◽  
Simple Variation ◽  
Resonance Detection

Abstract Double resonance level crossing detection cannot normally be used to record transitions between the quadrupole Zeeman levels. Neither can it be used if the quadrupole resonance frequency is larger than the proton NMR frequency in high field. A simple variation of the level crossing experiment is demonstrated which allows energy to be efficiently transferred from quadrupole to proton system and hence lead to detection in these two cases. In the case of the quadrupole Zeeman levels it allows transitions between the ±½ levels to be detected in a small magnetic field, allowing measurement of the asymmetry parameter (ƞ) for spin 3/2 systems. This is demonstrated for the 11B nucleus in triethanolamine borate. Detection of high frequency quadrupole transitions is demonstrated from which relaxation information is obtained.

New Methods of Nuclear Quadrupole Resonance

1990 ◽  
Vol 45 (3-4) ◽  
pp. 559-564 ◽  
Author(s):  
V. S. Grechishkin
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Double Resonance ◽  
Rf Pulses ◽  
The Past ◽  
New Methods ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Abstract New NQR methods, developed over the past years, are discussed: 1. Two frequency NQR double resonance, 2. the influence of strong off-resonance combination of rf pulses on demagnetized state in NQR, 3. remote NQR.

scholarly journals 14N Nuclear Quadrupole Resonance of Some Heterocyclic CompoundsviaNuclear Double Resonance

1978 ◽  
Vol 51 (4) ◽  
pp. 978-980 ◽  
Author(s):  
Takuya Maruizumi ◽  
Yukio Hiyama ◽  
Noriyuki Watanabe ◽  
Eiji Niki
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Double Resonance ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Nitrogen-14 quadrupole cross-relaxation spectroscopy

1988 ◽  
Vol 416 (1850) ◽  
pp. 149-178 ◽  
Keyword(s):  
Magnetic Field ◽  
Double Resonance ◽  
Relaxation Times ◽  
High Sensitivity ◽  
Lattice Relaxation ◽  
Cross Relaxation ◽  
Spin Lattice Relaxation ◽  
Proton Relaxation ◽  
Spin Lattice ◽  
Quadrupole Resonance

Cross-relaxation spectroscopy can be used as a sensitive method of detecting 14 N quadrupole-resonance signals in hydrogen-containing solids. The 1 H spin system is polarized in a high magnetic field that is then reduced adiabatically to a much lower value satisfying the level­-crossing condition, when the 1 H Zeeman splitting matches one of the 14 N quadrupole splittings. If the 14 N spin–lattice relaxation time is much shorter than that of the 1 H nuclei, a drastic loss of 1 H polarization occurs that is measured by recording the residual 1 H magnetic resonance signal after the sample has been returned to the higher field. The experimental cycle can be run in several different ways according to the relative values of the 1 H spin–lattice relaxation times ( T 1 ) in high and low field, the 14 N spin–lattice relaxation ( T 1Q ) and cross-polarization times ( T CP ), all of which can markedly influence the spectra. The line shapes are broadened by the presence of the magnetic field and Zeeman shifts of the peak frequencies also occur, for which simple corrections may be derived. The methods used have high sensitivity, particularly if the ratio T 1 / T 1Q is large. They have the advantage over other double-resonance techniques in that long proton T 1 values are not necessary for the success of an experiment; it is also possible to select conditions in which the recovered 1 H signal is directly proportional to the relative numbers of 14 N nuclei present and the magnitude of the cross-relaxation field. Multi-proton relaxation jumps also give rise to signals at subharmonics of the fundamental, whose relative intensities reflect the extent to which the 14 N and 1 H relaxation is coupled via their dipole–dipole interactions, which are not completely quenched in the finite magnetic fields necessary in cross-relaxation spectroscopy. These conclusions are illustrated in a number of 14 N spectra of compounds in which quadrupole-resonance signals have not previously been recorded.

A Low-Temperature High-Sensitivity Field-Cycling Spectrometer for Quadrupole Double Resonance Spectroscopy

1990 ◽  
Vol 45 (3-4) ◽  
pp. 595-598 ◽  
Author(s):  
M. M. P. Khurshid ◽  
F. Zhenye ◽  
J.A.S. Smith
Keyword(s):  
Variable Temperature ◽  
Double Resonance ◽  
High Sensitivity ◽  
Resonance Spectroscopy ◽  
Quadrupole Resonance ◽  
Field Cycling ◽  
Double Resonance Spectroscopy ◽  
Nuclear Quadrupole ◽  
The Magnetic Field ◽  
Sensitivity Field

Abstract This paper discusses the design of a variable-temperature high-sensitivity field cycling spectrometer for nuclear magnetic resonance and nuclear quadrupole double resonance experiments. The instrument is capable of detecting N-14 quadrupole resonance signals from samples as small as 0.1 g down to temperatures of 150 K. The magnetic field cycling is performed by mechanical transfer of the sample using a pair of switchable electromagnetic solenoids, in times of about 0.2 s.

1H - 17O Nuclear Quadrupole Double Resonance in DL-Proline

1990 ◽  
Vol 45 (5) ◽  
pp. 733-735 ◽  
Author(s):  
J. Seliger ◽  
V. Žagar ◽  
R. Blinc ◽  
P. K. Kadaba ◽  
D. Fiat
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Double Resonance ◽  
Unit Cell ◽  
The Other ◽  
Resonance Technique ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Abstract 17O nuclear quadrupole resonance spectra have been measured in an 17O enriched polycristalline sample of DL-proline with the help of 1H - 17O nuclear quadrupole double resonance technique. The results show the presence of eight chemically inequivalent oxygen sites corresponding to four inequivalent proline molecules in the unit cell. The oxygen sites may be grouped into two sets of four sites. One set with the short proton-oxygen distances belongs to the C - O • • • H groups whereas the other with the long proton-oxygen distances to the C = O groups

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