Different sensitivities of two optical magnetometers realized in the same experimental arrangement

In this article, operation of optical magnetometers detecting static (DC) and oscillating (AC) magnetic fields is studied and comparison of the devices is performed. To facilitate the comparison, the analysis is carried out in the same experimental setup, exploiting nonlinear magneto-optical rotation. In such a system, a control over static-field magnitude or oscillating-field frequency provides detection of strength of the DC or AC fields. Polarization rotation is investigated for various light intensities and AC-field amplitudes, which allows to determine optimum sensitivity to both fields. With the results, we demonstrate that under optimal conditions the AC magnetometer is about ten times more sensitive than its DC counterpart, which originates from different response of the atoms to the fields. Bandwidth of the magnetometers is also analyzed, revealing its different dependence on the light power. Particularly, we demonstrate that bandwidth of the AC magnetometer can be significantly increased without strong deterioration of the magnetometer sensitivity. This behavior, combined with the ability to tune the resonance frequency of the AC magnetometer, provide means for ultra-sensitive measurements of the AC field in a broad but spectrally-limited range, where detrimental role of static-field instability is significantly reduced.Comment: 9 pages, 6 figure

Zero-field NMR J-spectroscopy of organophosphorus compounds

Organophosphorus compounds are a wide and diverse class of chemicals playing a crucial role in living organisms. This aspect has been often investigated using nuclear magnetic resonance (NMR), which provides information about molecular structure and function. In this paper, we report the results of theoretical and experimental studies on basic organophosphorus compounds using zero-field NMR, where spin dynamics are investigated in the absence of a magnetic field with the dominant heteronuclear J-coupling. We demonstrate that the zero-field NMR enables distinguishing the chemicals owing to their unique electronic environment even though their spin systems have the same alphabetic designation. Such information can be obtained just in a single measurement, while amplitudes and widths of observed low-field NMR resonances enable the study of processes affecting spin dynamics. An excellent agreement between simulations and measurements of the spectra, particularly in the largest frequency J-couplings range ever reported in zero-field NMR, is demonstrated

Proton relaxometry of tree leaves at hypogeomagnetic fields

We report on a cross-species proton-relaxometry study in ex vivo tree leaves using nuclear magnetic resonance (NMR) at 7µT. Apart from the intrinsic interest of probing nuclear-spin relaxation in biological tissues at magnetic fields below Earth field, our setup enables comparative analysis of plant water dynamics without the use of expensive commercial spectrometers. In this work, we focus on leaves from common Eurasian evergreen and deciduous tree families: Pinaceae (pine, spruce), Taxaceae (yew), Betulaceae (hazel), Prunus (cherry), and Fagaceae (beech, oak). Using a nondestructive protocol, we measure their effective proton T2 relaxation times as well as track the evolution of water content associated with leaf dehydration. Newly developed “gradiometric quadrature” detection and data-processing techniques are applied in order to increase the signal-to-noise ratio (SNR) of the relatively weak measured signals. We find that while measured relaxation times do not vary significantly among tree genera, they tend to increase as leaves dehydrate. Such experimental modalities may have particular relevance for future drought-stress research in ecology, agriculture, and space exploration

Experimental setup for materials characterization using zero-field nuclear magnetic resonance.

Praca opisuje konstrukcję układu wykorzystywanego w eksperymencie magnetycznego rezonansu jądrowego (MRJ) w zerowym polu. W pierwszej części pracy przedstawiono podstawy teoretyczne techniki magnetycznego rezonansu jądrowego. Zaprezentowano przebieg typowego eksperymentu oraz scharakteryzowane istotne z punktu widzenia techniki oddziaływania. Następnie opisano zachowanie spinu jądrowego w zerowym polu magnetycznym. W tym rozdziale przedstawiono technikę spektroskopii J oraz przedyskutowano obrazowanie MRJ w niskich pola magnetycznych. W następnej sekcji przedstawiono teoretyczne podstawy zjawiska nieliniowej magnetorotacji oraz ich wykorzystanie do pomiaru pola magnetycznego.Dwa kolejne rozdziały przedstawiają część doświadczalną. Został tam przedstawiony układ eksperymentalny. Dokonano charakteryzacji parametrów zbudowanego magnetometru optycznego. W ostatniej sekcji opisano i przedyskutowano próbę pomiaru magnetyzacji jądrowej z pomocą magnetometru optycznego.Thesis describes construction of an experimental setup used in a zero-field NMR experiment. First section focuses on theoretical aspects of nuclear magnetic resonance. Experimental technique and inter-/intramolecular interactions characteristic for a conventional NMR experiment are presented. Next, nuclear spin behavior in zero and low magnetic field is discussed. This chapter contains information about J-Spectroscopy and NMR imaging at low magnetic field. In the following section, Nonlinear Magneto-Optical Rotation (NMOR) is explained in the context of optical magnetometry. Next two chapters center on experimental work. Technical details of the setup are presented, parameters of constructed magnetometer are investigated. Finally, an experimental effort to measure nuclear magnetization using an optical magnetometer is described. Results and possible technical shortcomings are discussed

Properties and applications of microstructured optical fibres

Tematem pracy są symulacyjne i doświadczalne badania własności światłowodów z rdzeniem zawieszonym istotnych z punktu widzenia spektroskopii absorpcyjnej.W pracy opisano propagację światła w strukturach światłowodowych, mechanizmy propagacji światła oraz istotne własności światłowodów mikrostrukturalnych.Za pomocą symulacji metodą elementów skończonych wyznaczono strukturę modów poprzecznych w prostym modelu światłowodu z rdzeniem zawieszonym.W ramach przedstawionej części eksperymentalnej zmierzono widma absorpcyjne dla roztworów barwnika kationowego w etanolu, które porównano z wcześniej wykonanymi pomiarami.This work focuses on computational and experimental studies of suspended-core fibers from the standpoint of absorption spectroscopy.Thesis describes propagation of light in fiber structures, mechanisms of light propagation and essential characteristics of microstructured optical fibers.The theoretical work is supported by computational analysis. The mode structure of a simple suspended-core fiber is determined using finite element method. In the experimental section absorption spectra are measured for ethanol solutions of a cationic dye using suspended-core fibers. The results are compared with previously made measurements

Nonlinear magneto-optical rotation with parametric resonance

We report on investigations of nonlinear magneto-optical rotation (NMOR) in rubidium vapor subjected to a modulated magnetic field and continuous-wave (CW) laser-light illumination. By superimposing modulation and a static (DC) magnetic field, we demonstrate the appearance of resonances at both small and large (compared to the ground-state relaxation rate) values of the static field. Since in conventional NMOR, there is no rotation at high fields, this suggests an existence of a novel mechanism generating anisotropy in the considered case, which we identify as parametric resonance. The experiments are performed using light of small ellipticity and rotation signals are significantly enhanced by combining atom-induced polarization rotation with a passive rotation induced with a wave plate. All the observations are supported with theoretical simulations. The density-matrix formalism and angular-momentum probability surfaces are used to provide intuitive explanation of the observed signals.Comment: 10 pages, 11 figure

Zero-field NMR J-Spectroscopy of Organophosphorus Compounds

In this paper, we report the results of theoretical and experimental studies on basic organophosphorus compounds using zero-field NMR, where spin dynamics are investigated in the absence of a magnetic field with the dominant heteronuclear J-coupling. We demonstrate that the zero-field NMR enables distinguishing the chemicals owing to their unique electronic environment even for identical spin systems. Such information can be obtained just in a single measurement, while amplitudes and widths of observed low-field NMR resonances enable to study of processes affecting spin dynamics. An excellent agreement between simulations and measurements of the spectra, particularly in the largest frequency J-couplings range ever reported in zero-field NMR is demonstrated

Zero-field J-Spectroscopy of Urea: Spin-Topology Engineering by Chemical-Exchange

Well-resolved and information-rich J-spectra are the foundation for chemical analysis based on zero-field NMR. Yet, even in relatively small molecules, the spectra may gain complexity, hindering the analysis. To address this problem, we investigate an example biomolecule characterized with a complex J-coupling network -- urea, a key metabolite in protein catabolism -- and demonstrate ways of simplifying its zero-field spectra by modifying spin topology. This goal is achieved by controlling pH-dependent chemical-exchange rates of 1H nuclei and varying the composition of the D2O/H2O mixture used as a solvent. Specifically, we demonstrate that by increasing hydrogen chemical-exchange rate in [13C, 15N2]-urea solution, the molecule, being an effective spin system XAB2A\u27B\u272, behaves as a much simpler XA2 system (where X = 13C, A = 15N, B = 1H), manifesting through a single narrow spectral peak. Additionally, we show that introducing spin-1 nuclei into the molecule and investigating J-spectra of 1H/D isotopologues of [15N2]-urea allows to study various isolated spin subsystems: XA2, (XA)B, and XB2 (here X = 15N, A = 1H, B = D), again greatly simplifying spectra analysis. The influence of the chemical exchange process on zero-field $J$-spectra for each urea solution is elucidated by theoretical studies, demonstrating solid agreement between results and simulations. This study shows the applicability of zero-field NMR to detect complex biomolecules in aqueous solutions, and it opens the means for future in vivo/in vitro biochemical investigations, particularly in biofluids with a high concentration of water

DataSheet_1_Proton relaxometry of tree leaves at hypogeomagnetic fields.pdf

We report on a cross-species proton-relaxometry study in ex vivo tree leaves using nuclear magnetic resonance (NMR) at 7µT. Apart from the intrinsic interest of probing nuclear-spin relaxation in biological tissues at magnetic fields below Earth field, our setup enables comparative analysis of plant water dynamics without the use of expensive commercial spectrometers. In this work, we focus on leaves from common Eurasian evergreen and deciduous tree families: Pinaceae (pine, spruce), Taxaceae (yew), Betulaceae (hazel), Prunus (cherry), and Fagaceae (beech, oak). Using a nondestructive protocol, we measure their effective proton T2 relaxation times as well as track the evolution of water content associated with leaf dehydration. Newly developed “gradiometric quadrature” detection and data-processing techniques are applied in order to increase the signal-to-noise ratio (SNR) of the relatively weak measured signals. We find that while measured relaxation times do not vary significantly among tree genera, they tend to increase as leaves dehydrate. Such experimental modalities may have particular relevance for future drought-stress research in ecology, agriculture, and space exploration.</p