Line shapes in nuclear quadrupole resonance spectroscopy

Bryant, P.J.; Hacobian, S

doi:10.1016/0022-2860(82)85200-9

Cited by 3 publications

(2 citation statements)

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“…127I), it has been shown that even for the best and most perfect crystalline samples, electrical broadening effects dominated [9,10]. As shown in a previous paper [10] with p-diiodobenzene, electrical broadening gives the ratio of 2.0 for the ratio of half widths of the upper and lower l27I lines.…”

Section: General Considerationsmentioning

confidence: 82%

Zeeman NQR Powder Line Shapes for Half Integral Spin Nuclei

Bryant

Hacobian

1986

Zeitschrift Für Naturforschung A

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A polycrystalline material was simulated by assuming a random distribution o f small crystalites. The effect o f a small applied m agnetic field on the N Q R lineshape was calculated for half integral spin nuclei ( / = 3/2, 5/2, 7/2 and 9 /2 ) using a theory based on Toyam a's work [11], The line shapes indicate qualitatively the half width ratios o f the upper and lower resonances (e.g. A v1/Av] for 1=5/2) and thus enables one to see generally whether the broadening mechanism is mainly due to m agnetic or electric effects. General ConsiderationsConventionally, the Zeeman effect in NQR has been studied by the variations in the splittings of the resonance of a spin 3/2 system as the orientation of a single crystal was varied in the applied field [1,2,3], Morino and Toyama [4] were the first to show that a distinct effect was also observable in polycrystalline samples. Brooker and Creel [5] and Darville, Gerard and Calende [6] have independent ly given a full analysis of the problem where the applied magnetic field and the r.f. field were parallel. This has since been extended to other orientations and nuclei [7,8].In most polycrystalline samples studied by us so far with multilevel spin systems containing halogen nuclei (e.g. 127I), it has been shown that even for the best and most perfect crystalline samples, electrical broadening effects dominated [9,10]. As shown in a previous paper [10] with p-diiodobenzene, electrical broadening gives the ratio of 2.0 for the ratio of half widths of the upper and lower l27I lines. It can be qualitatively shown from the calculated line shapes in this paper that the half width NQR line ratio due to magnetic interaction is significantly less than 1.0 . In order to observe such magnetic broadening effects almost perfect crystals of p-diiodobenzene had to be obtained but since the compound has a tendency to decompose in heat and light it was not possible to obtain the desired conditions. Hence, it is proposed to present in the first instance the theoretical prediction of line shapes. To a large extent the theoretical treatment is based on solutions of equations developed by Toyama [11]. 2, The Zeeman Perturbation for H alf Integral SpinWhen a static magnetic field is applied to a nuclear quadrupolar system, the energy levels are determined by solving the secular eqation for the entire perturbed nuclear quadrupolar Hamiltonian ST, where z r = H Q + Hm. (l)Here Hq is the pure (unperturbed) nuclear quadru polar Hamiltonian and H m is that describing the magnetic interaction and is given by Hm = -y i H ,where y is the magnetogyric ratio and IH is the scalar product of the nuclear spin and applied magnetic field vectors. In the NQR case, the Zeeman effect is studied with external fields of the order of 100 gauss [1]. The nuclear magnetic dipoledipole fields are about 1 or 2 gauss and therefore the following perturbation treatment is a valid approximation.The eigenvalues of the nuclear quadrupolar Hamiltonian for half integral spins with finite asym metry parameter are given by m 'T...

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Section: General Considerationsmentioning

confidence: 82%

Zeeman NQR Powder Line Shapes for Half Integral Spin Nuclei

Bryant

Hacobian

1986

Zeitschrift Für Naturforschung A

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“…There have been several theoretical studies done to clarify the physical sources of the broadening and to explore lineshapes for special cases [36][37][38][39][40][41][42][43][44]; however, a universal expression for lineshape that is appropriate for broadening caused by charged defects distributed randomly on a crystal lattice has not yet been established. The usual approach when analyzing PAC spectra is to assume that the distribution of EFGs leads to a Gaussian or Lorentzian distribution of frequencies.…”

Section: Defects and Diffusion Studied Using Pac Spectroscopymentioning

confidence: 99%

Perturbed Angular Correlation Spectroscopy – A Tool for the Study of Defects and Diffusion at the Atomic Scale

Zacate

Jaeger

2011

DDF

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Abstract. This paper provides an introduction to perturbed angular correlation (PAC) spectroscopy in the context of its application in the study of point defects and diffusion. It emphasizes what we anticipate to be of interest to non-PAC specialists who are interested in understanding variations in how PAC results are presented by different research groups and in how physical quantities such as defect formation energies, association energies, and migration barriers can be extracted from analysis of PAC spectra. Numerous citations are included to emphasize the universality of the analysis methods across different classes of materials including metallic, ceramic, and semiconducting compounds.

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Line broadening effects in nuclear quadrupole resonance

Bryant

Hacobian

1983

Journal of Molecular Structure

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Line shapes in nuclear quadrupole resonance spectroscopy

Cited by 3 publications

References 10 publications

Zeeman NQR Powder Line Shapes for Half Integral Spin Nuclei

Zeeman NQR Powder Line Shapes for Half Integral Spin Nuclei

Perturbed Angular Correlation Spectroscopy – A Tool for the Study of Defects and Diffusion at the Atomic Scale

Line broadening effects in nuclear quadrupole resonance

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