X-Band Rapid-Scan Electron Paramagnetic Resonance of Radiation-Induced Defects in Tooth Enamel

Yu, Zhelin; Romanyukha, Alexander

doi:10.1667/rr14032.1.1

Cited by 6 publications

(6 citation statements)

References 22 publications

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“…Improved S/N has also been observed for irradiated teeth [36] and irradiated clipped fingernails [37], which have potential applications for radiation dosimetry. At L-band the S/N for radicals observed in γ-irradiated solids is improved by factors of 20 to 35 [30].…”

Section: Improved Signal-to-noise For Rapid Scan Relative To Cwmentioning

confidence: 99%

Rapid-scan EPR imaging

Eaton

Shi

Woodcock

et al. 2017

Journal of Magnetic Resonance

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In rapid-scan EPR the magnetic field or frequency is repeatedly scanned through the spectrum at rates that are much faster than in conventional continuous wave EPR. The signal is directly-detected with a mixer at the source frequency. Rapid-scan EPR is particularly advantageous when the scan rate through resonance is fast relative to electron spin relaxation rates. In such scans, there may be oscillations on the trailing edge of the spectrum. These oscillations can be removed by mathematical deconvolution to recover the slow-scan absorption spectrum. In cases of inhomogeneous broadening, the oscillations may interfere destructively to the extent that they are not visible. The deconvolution can be used even when it is not required, so spectra can be obtained in which some portions of the spectrum are in the rapid-scan regime and some are not. The technology developed for rapid-scan EPR can be applied generally so long as spectra are obtained in the linear response region. The detection of the full spectrum in each scan, the ability to use higher microwave power without saturation, and the noise filtering inherent in coherent averaging results in substantial improvement in signal-to-noise relative to conventional continuous wave spectroscopy, which is particularly advantageous for low-frequency EPR imaging. This overview describes the principles of rapid-scan EPR and the hardware used to generate the spectra. Examples are provided of its application to imaging of nitroxide radicals, diradicals, and spin-trapped radicals at a Larmor frequency of ca. 250 MHz.

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Section: Improved Signal-to-noise For Rapid Scan Relative To Cwmentioning

confidence: 99%

Rapid-scan EPR imaging

Eaton

Shi

Woodcock

et al. 2017

Journal of Magnetic Resonance

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“…In particular, “rapid-scan” refers to the regime originally defined by Weger [19] in terms of the incident MW field B 1 , the magnetic-field scan rate d B 0 /d t (for field-swept RSEPR) and the relaxation times T 1 and T 2 [18, 19]:

true| \frac{B_{1}}{normald B_{0} / normald t} true| ≪ \sqrt{T_{1} T_{2}} .

In this rapid-scan regime, B 1 and d B 0 /d t can be selected to achieve improved signal-to-noise ratios (SNRs) relative to those attained by conventional CWEPR. This has been demonstrated for a variety of samples, such as nitroxides [20, 21], spin-trapped radicals [22], radiation-induced defects in tooth enamel [23] and defect states in solids, including DBs in a -Si:H [24]. Moreover, its applicability for quantitative intensity measurements has already been pointed out [25].…”

Section: Introductionmentioning

confidence: 99%

Using rapid-scan EPR to improve the detection limit of quantitative EPR by more than one order of magnitude

Möser

Lips

Tseytlin

et al. 2017

Journal of Magnetic Resonance

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X-band rapid-scan EPR was implemented on a commercially available Bruker ELEXSYS E580 spectrometer. Room temperature rapid-scan and continuous-wave EPR spectra were recorded for hydrogenated amorphous silicon powder samples. By comparing the resulting signal intensities the feasibility of performing quantitative rapid-scan EPR is demonstrated. For different hydrogenated amorphous silicon samples, rapid-scan EPR results in signal-to-noise improvements by factors between 10 and 50. Rapid-scan EPR is thus capable of improving the detection limit of quantitative EPR by at least one order of magnitude. In addition, we provide a recipe for setting up and calibrating a conventional pulsed and continuous-wave EPR spectrometer for rapid-scan EPR.

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“…The source dose rate was 0.55 Gy/min. More details on irradiation conditions and sources calibration can be found in reference (21) . After irradiation, samples were stored in a refrigerator at 4 o C. When samples were outside of the refrigerator, tubes were protected from ultraviolet radiation by wrapping with aluminum foil.…”

Section: Methodsmentioning

confidence: 99%

“…Processing of the rapid scan data was performed as previously reported (21) , using software written in MatLab. The residual background that remained after removal of the rapid scan background was fit to a fourth order polynomial and subtracted.…”

Section: Methodsmentioning

confidence: 99%

“…The method has provided substantially improved signal-to-noise (S/N) relative to CW EPR for a wide range of samples including paramagnetic defects in solids (20) , the radiationinduced defects in teeth (21) , defects in gamma irradiated solids (22) and immobilized organic radicals (23) . These papers demonstrate the improvement in S/N that can be achieved by rapid scan for samples with a wide range of relaxation times.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Continuous Wave and Rapid Scan X-band Electron Paramagnetic Resonance of Irradiated Clipped Fingernails

Elajaili

McPeak

Romanyukha³

et al. 2016

Radiat Prot Dosimetry

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X-band rapid scan electron paramagnetic resonance (EPR) measures the free radicals in irradiated clipped fingernails with higher signal-to-noise (S/N) and lower standard deviation of the signal amplitude for replicate measurements than does conventional continuous wave (CW) EPR in the same measurement time. For a clipped fingernail sample irradiated to 10 Gy and data acquisition time of 30 s with B 1 = 8.5 μT, the S/N for rapid scan is >2000 for the absorption spectrum and 1200 for the corresponding first derivative. The standard deviation for replicate measurements of signal amplitude is~1%. For CW spectra, the S/N depends on the modulation amplitude. The CW signal has a first derivative peak-to-peak linewidth of 0.95 mT. For 30 s of CW acquisition time, the S/N was 30 for a conservative modulation amplitude of 0.2 mT and B 1 of 2.3 μT or 90 for a modulation amplitude of 0.4 mT and B 1 of 3.2 μT, which resulted in standard deviations of replicate measurements of 5% or 2%, respectively.

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X-Band Rapid-Scan Electron Paramagnetic Resonance of Radiation-Induced Defects in Tooth Enamel

Cited by 6 publications

References 22 publications

Rapid-scan EPR imaging

Rapid-scan EPR imaging

Using rapid-scan EPR to improve the detection limit of quantitative EPR by more than one order of magnitude

Comparison of Continuous Wave and Rapid Scan X-band Electron Paramagnetic Resonance of Irradiated Clipped Fingernails

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