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Titolo:
Determination of quadrupole parameters with a composite pulse for spurioussignal suppression
Autore:
Millot, Y; Man, PP;
Indirizzi:
Univ Paris 06, Lab Chim Surfces, CNRS, FRE 2312, F-75252 Paris 05, France Univ Paris 06 Paris France 05 , CNRS, FRE 2312, F-75252 Paris 05, France
Titolo Testata:
JOURNAL OF MAGNETIC RESONANCE
fascicolo: 1, volume: 150, anno: 2001,
pagine: 10 - 16
SICI:
1090-7807(200105)150:1<10:DOQPWA>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
SOLID-STATE NMR; MAGNETIC-RESONANCE SPECTROSCOPY; NUCLEI; ECHOES; PHASE;
Keywords:
spurious signal suppression; half-integer quadrupole spin; composite-pulse sequence; featureless lineshape; spin-population quantification;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Physical, Chemical & Earth Sciences
Citazioni:
23
Recensione:
Indirizzi per estratti:
Indirizzo: Millot, Y Univ Paris 06, Lab Chim Surfces, CNRS, FRE 2312, 4 Pl Jussieu,tour 55,Casier 196, F-75252 Paris 05, France Univ Paris 06 4 Pl Jussieu,tour 55,Casier 196 Paris France 05 e
Citazione:
Y. Millot e P.P. Man, "Determination of quadrupole parameters with a composite pulse for spurioussignal suppression", J MAGN RES, 150(1), 2001, pp. 10-16

Abstract

Spurious signals such as the piezoelectric signal from a ferroelectric crystal or the ringing signal from the NMR probe head tuned for low gyromagnetic ratio nuclei are often observed in pulsed NMR, Both signals are cancelled using the Hahn echo sequence with appropriate phase cyclings. The presentpaper applies a composite-pulse sequence to cancel the ringing signal. Themain advantage of this sequence over the Hahn echo sequence is in the simplicity of optimizing the line intensity: the optimization of only one pulseduration far this sequence but of two pulse durations and the interpulse delay for the Hahn echo sequence. We are interested in half-integer quadrupole spins (I = 3/2, 5/2, 7/2, and 9/2), which means that we must consider the first-order quadrupole interaction during the pulses. For simplicity, we deal mainly with spin I = 3/2 nuclei. Since the central-line intensity depends on the ratio of the quadrupole coupling-constant (QCC) to the amplitudeof the RF pulse, we can determine the QCC from a featureless lineshape by fitting the variation of the experimental central-line intensity for increasing pulse duration with theoretical results. Contrary to the one-pulse sequence where the central-line intensity is proportional to the pulse duration if the latter is short, there is no such condition with the composite-pulse sequence. In other words, this sequence does not allow us to quantify the relative spin populations in powders. The size of the sample must be muchsmaller than that of the RF coil in order for the RF magnetic field to become homogeneous for the sample. We used Rb-87 (I = 3/2) in an aqueous solution of RbCl and in RbNb2O5-F powder Xe-131 (I = 3/2) of xenon gas physisorbed in Na-Y zeolite, and Na-23 (I = 3/2) in two well-known powders (NaNO3 and NaNO2) to support our theoretical result. (C) 2001 Academic Press.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 19/01/20 alle ore 09:24:40