Analysis of quadrupolar spin echoes in a series of V3X compounds

Schoep, G.K.; Valk, H.; Frijters, G.A.M.; Kok, H.B.; Poulis, N.J.

doi:10.1016/0031-8914(74)90241-9

Cited by 19 publications

(10 citation statements)

References 5 publications

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“…However, we have found that the (p/2) 7 x -t-p 7 y sequence applied for 139 La nuclei in LaOs 4 As 12 retained small amounts of quadrupolar echoes, as was also observed for the spin I=5/2 nuclei 27 Al and 127 I in NiAl and KI, respectively [18]. Our measurements confirm earlier theoretical predictions [19] that the maximum height of the 2t echo for spin I=7/2 is not obtained for b=p, but for b opt =p/6, in agreement also with the study of the 59 Co 2t echo in V 3 Co [20]. Under this condition, however, other echoes at ta2t are strongly attenuated.…”

Section: Article In Presssupporting

confidence: 93%

“…Here, the two radio-frequency (RF) pulses are separated by an interpulse delay t and the time origin starts from the end of the first pulse. For I43/2, under certain favorable conditions, extra echoes (allowed and forbidden) can be elicited [17][18][19][20]. For a more recent review see Ref.…”

Section: Article In Pressmentioning

confidence: 97%

“…To our knowledge based on Ref. [21] only one paper has dealt with quadrupolar echoes in a spin I=7/2 system, 51 V in a series of V 3 X compounds and 59 Co in V 3 Co [20].…”

Section: Article In Pressmentioning

confidence: 99%

See 2 more Smart Citations

Multiple quadrupolar spin echoes in the La-filled skutterudite LaOs4As12

Nowak¹,

Żogał²,

Henkie³

et al. 2009

Solid State Nuclear Magnetic Resonance

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Section: Article In Presssupporting

confidence: 93%

Section: Article In Pressmentioning

confidence: 97%

See 1 more Smart Citation

Multiple quadrupolar spin echoes in the La-filled skutterudite LaOs4As12

Nowak¹,

Żogał²,

Henkie³

et al. 2009

Solid State Nuclear Magnetic Resonance

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“…quadrupole spins (I = 5/2, 7/2, and 9/2) for the case when second-order quadrupole interaction is negligible. 10,11,[17][18][19][20][21] The considered spin systems were inhomogeneously broadened by magnetic as well as quadrupole interactions, which resulted in the prediction of so-called allowed and forbidden echoes. More specifically, an allowed echo is the refocusing of two 1Q and two nQ coherences generated by first pulse while a forbidden echo is the refocusing of two couples of nQ coherences.…”

Section: A Nmr Spectramentioning

confidence: 99%

Order-disorder phase transition in CePt4In: Evidence fromIn115and
Nowak
¹

2011
Phys. Rev. B

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We present the results of nuclear magnetic resonance (NMR) studies on CePt 4 In crystallizing at ambient temperature in an ordered cubic MgCu 4 Sn-type structure (space group F-43m, no. 216). The 115 In and 195 Pt NMR powder spectra have provided microscopic evidence for the occurrence of the phase transition suggested by the specific heat anomaly at T 0 = 205 K. Single-site (multiple-site) 195 Pt (I = 1/2) NMR spectra are observed above (below) T 0 , while the single-site 115 In (I = 9/2) NMR signal disappears below T 0 . The Solomon echoes of half-integer quadrupolar nuclei with spin I = 9/2 have been observed. The Knight shifts 115 K iso (T) and 195 K α (T) (α = //, ⊥, iso, ax) scale linearly with magnetic susceptibility χ (T). 195 Pt NMR exhibits strong anisotropy of the Knight shift and nuclear spin-lattice relaxation rate due to the huge anisotropy of hyperfine fields (H // /H ⊥) ≈ 43. The (1/T 1 ) iso are fast and temperature independent for both 115 In and 195 Pt nuclei, indicating that the spin fluctuation of the 4f electrons has a local nature at the Ce sites.

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“…Two approaches have been adopted, the first using the multipole operator formalism [41] and the second the fictitious spin-1/2 operator formalism [40]. They extend early work which dealt mainly with the special case of small or/and large tOo/tO~f ratios [26,[42][43][44][45][46][47][48][49][50][51][52]. As only ~(~1) was taken into account in the calculations, the central transition echo at " 91 ~ "t'2 for ~2 > Tr~D (duration of the FID) was not predicted.…”

Section: Case I = 3/2mentioning

confidence: 99%

Excitation conditions for quantitative determination of quadrupolar spins with one pulse or spin-echo sequences in solid-state NMR

Man

1993

Appl. Magn. Reson.

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One of the major problems concerning quadrupolar spins in solid-state NMR is their quantification. Ir the optimal excitation conditions with one radio-frequency pulse are widespread known now, this is not the case with the spin-echo sequences. This paper reports some theoretical predictions and their limitations concerning quantification with the echo obtained with spin-echo resonances. To realize that, first, the relative line intensity of a transition ( m + 1, m) is defined in order to allow the comparison of results from different authors. Then results concerning one pulse excitation on a spin I= 3/2 are summarized. The condition of short pulse excitation is generalized to higher spins using the Pauli matrices applied to the two extreme cases: hard pulse of non selective excitation, and selective excitation. Finally the same procedure has been foUowed for the spin-echo sequence involving two x-pulses. It was shown that the optimum conditions are: both the pulse length must be sufficiently short, and the interpulse delay should be taken as short as the duration of the FID provided the phase of the second pulse alternates without changing the receiver phase. In these conditions, the relative echo amplitude depends lineady on the first pulse length and quadraticaUy on the second. The limitations are: the homonuclear magnetic dipolar interaction must be much smaller than the heteronuclear case which must be itself much smaller than the amplitude of the pulse. Furthermore, quantification with the echo requires the determination of the spin-spin relaxation time as well.

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Analysis of quadrupolar spin echoes in a series of V3X compounds

Cited by 19 publications

References 5 publications

Multiple quadrupolar spin echoes in the La-filled skutterudite LaOs4As12

Multiple quadrupolar spin echoes in the La-filled skutterudite LaOs4As12

Order-disorder phase transition in CePt4In: Evidence fromIn115and
Nowak
¹

2011
Phys. Rev. B

Excitation conditions for quantitative determination of quadrupolar spins with one pulse or spin-echo sequences in solid-state NMR

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Analysis of quadrupolar spin echoes in a series of V3X compounds

Cited by 19 publications

References 5 publications

Multiple quadrupolar spin echoes in the La-filled skutterudite LaOs4As12

Multiple quadrupolar spin echoes in the La-filled skutterudite LaOs4As12

Order-disorder phase transition in CePt4In: Evidence fromIn115andNowak1 2011Phys. Rev. B

Excitation conditions for quantitative determination of quadrupolar spins with one pulse or spin-echo sequences in solid-state NMR

Contact Info

Product

Resources

About

Order-disorder phase transition in CePt4In: Evidence fromIn115and
Nowak
¹

2011
Phys. Rev. B