Importance of Transition Probability Values for Accurate EPR Concentration Measurements

Siebert, D.; Dahlem, J.; Nagy, Vitaly

doi:10.1021/ac00089a009

Cited by 14 publications

(5 citation statements)

References 8 publications

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“…Lineshape analysis of electron spin resonance (ESR) spectroscopy has been applied to determine the concentration of paramagnetic impurities. Although high precision of the spin concentration determination (∼ 3 %) has been achieved at X-band ESR spectroscopy 24 , the method remains challenging for wide applications as it highly depends on the choice of the reference sample 25 , position of the samples in the cavity 26,27 , spin relaxations 28 and requires precise knowledge of effect of samples on microwave fields 29,30 , filling 25,30 and quality factors of the cavity 25,29 , microwave and modulation field distributions over the sample volume [31][32][33] .…”

Section: Introductionmentioning

confidence: 99%

Determination of nitrogen spin concentration in diamond using double electron-electron resonance

Stepanov

Takahashi

2016

Phys. Rev. B

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Diamond has been extensively investigated recently due to a wide range of potential applications of nitrogen-vacancy (NV) defect centers existing in a diamond lattice. The applications include magnetometry and quantum information technologies, and long decoherence time (T 2) of NV centers is critical for those applications. Although it has been known that T 2 highly depends on the concentration of paramagnetic impurities in diamond, precise measurement of the impurity concentration remains challenging. In the preset work, we show a method to determine a wide range of the nitrogen concentration (n) in diamond using a wide-band high-frequency electron spin resonance and double electron-electron resonance spectrometer. Moreover, we investigate T 2 of the nitrogen impurities and show the relationship between T 2 and n. The method developed here is applicable for various spin systems in solid and implementable in nanoscale magnetic resonance spectroscopy with NV centers to characterize the concentration of the paramagnetic spins within a microscopic volume.

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Section: Introductionmentioning

confidence: 99%

Determination of nitrogen spin concentration in diamond using double electron-electron resonance

Stepanov

Takahashi

2016

Phys. Rev. B

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“…For this reason, we adopted ICP-MS technique for Mn(II) quantification and used EPR spectra to estimate the relative concentration of Mn(II) and spin defects in GO. As reported in Materials and Methods section, the comparison of the relative abundance between two different paramagnetic species with different lineshapes is not straightforward in EPR, so we referred to [39,40] and, taking into account the different transition probability, we calculated the ratio between the Mn and the defect centers, ranging from 4.3:1 to 1.7:1. The smaller fraction of structural defects compared to the manganese atoms gives them critical importance and effectiveness, being the former the main source of relaxation in MRI in our samples.…”

Section: Discussionmentioning

confidence: 99%

“…Due to noise in the experimental spectra we observed some degree of variation in the Mn(II) line width values (4.7-6.4 mT). The different transition probability was considered [39,40] to obtain the ratio between the two paramagnetic species.…”

Section: Electron Paramagnetic Resonance (Epr)mentioning

confidence: 99%

Disentangling the intrinsic relaxivities of highly purified graphene oxide

Fioravanti,

Galante,

Fattibene

et al. 2024

Nanotechnology

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The chemistry of Contrast Agents (CAs) for Magnetic Resonance Imaging (MRI) applications is an active area of research and, in recent work, it was shown that CA-based Graphene Oxide (GO) has valuable properties for biomedical uses. GO has a potential as MRI CAs thanks to several functionalities, like its ability to penetrate tissues and cell membranes, as well as easy coupling with therapeutic agents, therefore showing the potential for both a diagnostic and therapeutic role. In this study, we performed a thorough cleaning of the GO sample (synthesized using a modified Hummers method), minimizing the amount of residual manganese down to 73 ppm. Using a wide range of physical-chemical methods (morphology, chemical composition, elemental analysis, spectroscopies, and imaging), we characterized the intrinsic longitudinal and transverse relaxivities of highly purified GO nanosheets. X-band Electron Paramagnetic Resonance (EPR) allowed to recognize the paramagnetic species involved, and 1.0 T MRI was used to disentangle the relative contributions to the MRI contrast of pristine GO nanosheets arising from structural defects and residual paramagnetic manganese impurities embedded in the nanomaterial. Although experiments show that the MRI relaxivity of GO nanosheets arises from the cumulative effect of structural defects and paramagnetic impurities, we conclude that the latter contribution to the longitudinal and transverse relaxivities becomes irrelevant for highly purified (pristine) GO. This novel finding clearly demonstrate that, apart from trivial manganese inclusion, pristine GO produces an inherent MRI response via structural defects, and therefore it is on its own a suitable candidate as MRI contrast agent.

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“…4b) and were calibrated to the standard using eqn (S4) (ESI†), which accounts for the g-dependence of the ESR transition probability. 120…”

Section: Methodsmentioning

confidence: 99%

“…4b) and were calibrated to the standard using eqn (S4) (ESI †), which accounts for the g-dependence of the ESR transition probability. 120 Raman spectra (Fig. S7-S9, ESI †) were measured to assess sample structure and composition before and after irradiation.…”

Section: Characterization Of Cryogenic Samplesmentioning

confidence: 99%