Rapid detection of arsenic minerals using portable broadband NQR

Lehmann-Horn, J. A.; Miljak, D.G.; O’Dell, Luke A.; Yong, R.; Bastow, Timothy J.

doi:10.1002/2014gl061386

Cited by 9 publications

(4 citation statements)

References 31 publications

(35 reference statements)

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“…Recently, we have determined the 75 As NQR frequencies of selected arsenic minerals by systematic stepped frequency scanning over a large frequency range [7]. The results were well modelled by first principles ab initio calculations based on density functional theory (DFT) [8], and we demonstrated later that NQR can be a useful tool to detect the presence of contaminant phases such as arsenic or antimony in mining processes [9]. In such industrial measurement applications, it is crucial to maximize sensitivity and reduce measurement times [10].…”

Section: Introductionmentioning

confidence: 84%

75 As NQR studies on FeAs 2

Lehmann-Horn

Yong

Miljak

et al. 2015

Solid State Nuclear Magnetic Resonance

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Section: Introductionmentioning

confidence: 84%

75 As NQR studies on FeAs 2

Lehmann-Horn

Yong

Miljak

et al. 2015

Solid State Nuclear Magnetic Resonance

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“…The interest in efficient near-field representation is particularly motivated by the recent development of large magnetic resonance loop sensor arrays that are used for measurement of specific "zero-field" mineral resonances that occur in the HF to VHF range [33], operated both in air and over earth layers [34]. The sensing zone is generally limited to the extreme near field, corresponding to approximately one loop diameter from the loop centre.…”

Section: Introductionmentioning

confidence: 99%

Exact Expressions for the Near Field of a Thin Uniform Circular Loop Current with Application to Loops Lying on a Half Space

Miljak

2024

PIER B

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Exact analytic solutions for the electromagnetic field due to a thin, time varying uniform circular loop current are presented. The solutions are provided in the form of a power series with respect to wavenumber. The coefficients of the series are real functions of the spatial coordinates and loop radius and involve recursions of complete elliptic integrals or finite sums of elementary functions. Explicit expressions for the magnetic vector potential and electric and magnetic fields are provided for both cylindrical and spherical coordinate systems. The expressions are adapted for computing the electric field and axial magnetic field on the interface of two half spaces generated by a current loop lying on the half-space interface. Expressions for the self and mutual loop impedances are provided for both the free-space and interface case. Computed examples are given for specific frequency and half-space parameters and are compared to known solutions based on spherical Hankel functions or direct integration. The solutions are shown to be particularly efficient in the near field. Their derivation is motivated by recent developments of large sensors used in magnetic resonance sensing of minerals.

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“…Basic investigations concerning polymorphism in minerals can be found, for example, in References [16,17]. Practical implementations and applications for the identification and quantification of As compounds in processing pipelines of minery have been reported in Reference [18]. Several publications describe the application of NQRS for the investigation of phase transitions in crystalline samples, for example, References [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Tris(2-Methoxyphenyl)Bismuthine Polymorphism Characterized by Nuclear Quadrupole Resonance Spectroscopy

et al. 2019

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Based on the previous identification of metastable polymorphs in crystalline triphenylbismuth by nuclear quadrupole resonance spectroscopy (NQRS), the potential formation of similar phases was studied in Tris(2-Methoxyphenyl)Bismuthine. To this end, commercial samples with known NQRS properties were molten and re-crystallized at different speeds (shock freezing in different coolants versus slow cooling inside of a heater). In all recrystallization products we have identified a new crystal phase which has not been observed after synthesis from a solution. The new crystallographic structure has been confirmed by X-ray diffraction (XRD). The newly isolated polymorph crystallizes in the monoclinic space group P2(1)/c with only one molecule in the asymmetric unit and consequently only one 5/2-7/2 transition is observed at 88.75 MHz at 310 K. In contrast, the two transitions at 89.38 and 89.29 MHz for the well-known trigonal polymorph originate from two crystallographically distinct molecules of Tris(2-methoxy-Phenyl)Bismuthine in the asymmetric unit. Additional relaxometric NQRS shows distinctly different T2 relaxation times for the new polymorph when compared to the original samples. Additional phase transitions could not be observed during temperature sweeps between 153K and 323K.

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Rapid detection of arsenic minerals using portable broadband NQR

Cited by 9 publications

References 31 publications

75 As NQR studies on FeAs 2

75 As NQR studies on FeAs 2

Exact Expressions for the Near Field of a Thin Uniform Circular Loop Current with Application to Loops Lying on a Half Space

Tris(2-Methoxyphenyl)Bismuthine Polymorphism Characterized by Nuclear Quadrupole Resonance Spectroscopy

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