Two-dimensional zero-field nutation nuclear quadrupole resonance spectroscopy

Harbison, Gerard S.; Slokenbergs, Andris; Barbara, Thomas M.

doi:10.1063/1.456433

Cited by 89 publications

(70 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In recent years some ingenious experimental methods have been invented to extract these parameters without applying a field. This include 1D [1], and amplitude [2] and phase modulated [3] 2D nutation spectroscopy. However, these methods are based on the assumptions that the NQR line is much narrower than the effective nutation frequency (which is on the order of γH 1 where H 1 is the radio frequency (RF) field and γ is the nuclear gyromagnetic ratio).…”

Section: Introductionmentioning

confidence: 99%

Pure nuclear quadrupole resonance determination of the electric field gradient asymmetry for broad lines

Levy

Keren

2004

Journal of Magnetic Resonance

View full text Add to dashboard Cite

We present an angle dependent nuclear quadrupole resonance (ADNQR) method to determine the electric field gradient asymmetry parameter η in systems where the resonance line is so broad that the radio frequency field can excite only a portion of the nuclear spins. In this situation the recently developed spectroscopic methods are not applicable. ADNQR is useful for single crystals and oriented powders, and, for small η determines η 4 . Therefore, it can be used to evaluate fluctuations in η due to inhomogeneities. We demonstrate the application of ADNQR experimentally to oriented superconducting YBa2Cu3O7 powder.

show abstract

Section: Introductionmentioning

confidence: 99%

Pure nuclear quadrupole resonance determination of the electric field gradient asymmetry for broad lines

Levy

Keren

2004

Journal of Magnetic Resonance

View full text Add to dashboard Cite

show abstract

“…4͑a͒, in which we show the intensity of the ͑3/2-1/2͒ transition of the 123 Sb nucleus in antimony͑III͒ chloride at an observation frequency of 2 ϭ37.400 MHz, as a function of the length of a pulse on the ͑5/2-3/2͒ transition. The nominal nutation frequency is 65 kHz, however, because the precession frequency of individual crystallites in a powder NQR sample depends on the orientation of the electric field gradient tensor relative to the coil axis, 2,9 this is merely the predominant value in the powder. The maximum enhancement measured for the ͑3/2-1/2͒ transition is 2.64, corresponding to a nominal pulse on the 5/2-3/2 transition, which is close to the maximum possible value for a single crystal of ( 1 ϩ 2 )/ 2 ϭ2.81.…”

Section: Longitudinal Coherence Transfermentioning

confidence: 99%

“…The first such applications [1][2][3] were directed at extracting the asymmetry parameter, ordinarily unavailable for spin 3/2 nuclei at zero field. For spins 5/2 and higher, can be obtained from the ratios of two or more spectral frequencies observable for each species.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional nuclear magnetic resonance correlation spectroscopy at zero field

Liao

Harbison

1999

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

Three methods for two-dimensional correlation nuclear magnetic resonance spectroscopy at zero field are discussed. All three involve coherence transfer via longitudinal polarization, double quantum coherence, or both in parallel. The double quantum pulse sequences exploit the spinor property of spin states. These sequences have been applied to connected ⌬mϭ1 transitions, as well as for the indirect detection of forbidden or nearly forbidden ⌬mϾ1 transitions. © 1999 American Institute of Physics. ͓S0021-9606͑99͒00331-1͔ INTRODUCTIONDespite their success in high-field nuclear magnetic resonance ͑NMR͒, extension of multidimensional Fourier transform methods to zero-field NMR has been limited. There are several legitimate reasons for this; principally, high-field spectra are often complex, with literally thousands of resonance signals; in such systems, two-dimensional methods are necessary both to increase the resolution and provide spectral assignments. In contrast, zero-field spectra are often very simple, both because of the paucity of chemically distinct species in the material, and because there is usually only a single significant term in the spin Hamiltonian, resulting in a lack of spectral multiplicity.Nonetheless, there are occasions when multidimensional techniques can be usefully applied at zero field. The first such applications [1][2][3] were directed at extracting the asymmetry parameter, ordinarily unavailable for spin 3/2 nuclei at zero field. For spins 5/2 and higher, can be obtained from the ratios of two or more spectral frequencies observable for each species. However, in samples with several distinct quadrupolar species, such as partially deuterated amine and amino acid hydrohalides, 4 connected transitions must be correctly assigned to extract this information. This was the purpose of our original nuclear quadrupolar correlation experiment. 5 Since then, we have also applied the experiment to inhomogeneously broadened systems, since in such systems the quadrupolar frequencies are strongly correlated. The resulting removal of this broadening has allowed us to estimate the hexadecapolar interaction for 127 I In cadmium iodide with high accuracy. 6 Figure 1 correlates the energy levels and transitions for a spin 5/2 nucleus at zero field with the high-field energy levels. At zero field, the high-field eigenstates, labeled by the quantum number m associated with the z component of the angular momentum, become twofold degenerate, with the Ϯm states having the same energy. There are two connected single-quantum transitions at frequencies 1 and 2 and one double-quantum transition at dq ϭ 2 ϩ 1 . For an axially symmetric electric field gradient 2 ϭ2 1 , and the eigenstates are identical to the high-field eigenstates. If the electric field gradient is not axially symmetric, the ratio between the two single-quantum frequencies decreases until it reaches a value of 1 for an asymmetry parameter ϭ(ٌE yy ϪٌE xx )/ٌE zz ϭ1, and concomitantly there is some mixing of the high-field eigenstates, the mϭϮ5/2 state...

show abstract

“…This complicates the problem and demands additional equipment. Recently Harbison and Slokenbergs [1,2] suggested a new two-dimensional nutation NQR ex periment which uses the singularities of the nutation spectrum of a powder sample for the determination of the asymmetry parameter rj. The calculations of the nutation spectra for 1=3/2 and for powders [1,2] were made without consideration of the spectrometer frequency offset Av of the relative to the Larmor fre quency, i.e.…”

Section: Introductionmentioning

confidence: 99%