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Dmitry Budker - One of the best experts on this subject based on the ideXlab platform.
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detection of radio frequency magnetic fields using nonlinear magneto Optical Rotation
Physical Review A, 2007Co-Authors: M P Ledbetter, Dmitry Budker, Szymon Pustelny, S M Rochester, Victor M Acosta, Valeriy V YashchukAbstract:We describe a room-temperature alkali-metal atomic magnetometer for detection of small, high-frequency magnetic fields. The magnetometer operates by detecting Optical Rotation due to the precession of an aligned ground state in the presence of a small oscillating magnetic field. The resonance frequency of the magnetometer can be adjusted to any desired value by tuning the bias magnetic field. Based on experimentally measured signal-to-noise ratio, we demonstrate a sensitivity of $100\phantom{\rule{0.3em}{0ex}}\mathrm{pG}∕\sqrt{\mathrm{Hz}}$ (rms) in a $3.5\text{\ensuremath{-}}\mathrm{cm}$-diameter paraffin coated cell. Assuming detection at the photon shot-noise limit, we project a sensitivity as low as $25\phantom{\rule{0.3em}{0ex}}\mathrm{pG}∕\sqrt{\mathrm{Hz}}$ (rms).
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nonlinear magneto Optical Rotation with frequency modulated light in the geophysical field range
Physical Review A, 2006Co-Authors: Victor M Acosta, Dmitry Budker, W Gawlik, Szymon Pustelny, Jerzy Zachorowski, S M Rochester, D Jackson F Kimball, M P Ledbetter, D C Hovde, Valeriy V YashchukAbstract:Recent work investigating resonant nonlinear magneto-Optical Rotation (NMOR) related to long-lived $({\ensuremath{\tau}}_{\mathrm{rel}}\ensuremath{\sim}1\mathrm{s})$ ground-state atomic coherences has demonstrated potential magnetometric sensitivities exceeding ${10}^{\ensuremath{-}11}\phantom{\rule{0.3em}{0ex}}\mathrm{G}∕\sqrt{\mathrm{Hz}}$ for small $(\ensuremath{\lesssim}1\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{G}$) magnetic fields. In the present work, NMOR using frequency-modulated light (FM NMOR) is studied in the regime where the longitudinal magnetic field is in the geophysical range$(\ensuremath{\sim}500\mathrm{mG})$, of particular interest for many applications. In this regime a splitting of the FM NMOR resonance due to the nonlinear Zeeman effect is observed. At sufficiently high light intensities, there is also a splitting of the FM NMOR resonances due to ac Stark shifts induced by the Optical field, as well as evidence of alignment-to-orientation conversion type processes. The consequences of these effects for FM-NMOR-based atomic magnetometry in the geophysical field range are considered.
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nonlinear magneto Optical Rotation with amplitude modulated light
Applied Physics Letters, 2006Co-Authors: W Gawlik, L Krzemien, Szymon Pustelny, D Sangla, Jerzy Zachorowski, Miriam T Graf, Alexander O Sushkov, Dmitry BudkerAbstract:The technique of nonlinear magneto-Optical Rotation with amplitude modulated light is developed. The technique is an alternative to its counterpart with frequency modulated light and can be applied to sensitive measurements of magnetic fields ranging from microgauss to the Earth-field level. The Rotation signals exhibit nontrivial features such as narrowed non-Lorentzian line shapes and multicomponent resonances.
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pump probe nonlinear magneto Optical Rotation with frequency modulated light
Physical Review A, 2006Co-Authors: Szymon Pustelny, Valeriy V Yashchuk, W Gawlik, S M Rochester, D Jackson F Kimball, Dmitry BudkerAbstract:Specific types of atomic coherences between Zeeman sublevels can be generated and detected using a method based on nonlinear magneto-Optical Rotation with frequency-modulated light. Linearly polarized, frequency-modulated light is employed to selectively generate ground-state coherences between Zeeman sublevels for which m=2 and m=4 in 85 Rb and 87 Rb atoms, and additionally m=6 in 85 Rb. The atomic coherences are detected with a separate, unmodulated probe light beam. Separation of the pump and probe beams enables independent investigation of the processes of creation and detection of the atomic coherences. With the present technique the transfer of the Zeeman coherences, including high-order coherences, from excited to ground state by spontaneous emission has been observed.
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nonlinear magneto Optical Rotation with amplitude modulated light amor
arXiv: Optics, 2005Co-Authors: W Gawlik, L Krzemien, Szymon Pustelny, D Sangla, Jerzy Zachorowski, Miriam T Graf, Alexander O Sushkov, Dmitry BudkerAbstract:A new technique of nonlinear magneto-Optical Rotation with amplitude modulated light is developed. The technique is an alternative to its counterpart with frequency modulated light and can be applied to sensitive measurements of magnetic fields ranging from microgauss to the Earth-field level. The Rotation signals exhibit nontrivial features like narrowed non-Lorentzian lineshapes and multi-component resonances.
P J Stephens - One of the best experts on this subject based on the ideXlab platform.
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determination of the absolute configurations of natural products via density functional theory calculations of vibrational circular dichroism electronic circular dichroism and Optical Rotation the iso schizozygane alkaloids isoschizogaline and isoschizogamine
Chirality, 2008Co-Authors: P J Stephens, F J Devlin, Jianjung Pan, Marie Urbanova, Ondřej Julinek, Josef HajicekAbstract:The development of density functional theory (DFT) methods for the calculation of vibrational circular dichroism (VCD), electronic circular dichroism (ECD), and transparent spectral region Optical Rotation (OR) has revolutionized the determination of the absolute configurations (ACs) of chiral molecules using these chi- rOptical properties. We report the concerted application of DFT calculations of VCD, ECD, and OR to the determination of the ACs of the isoschizozygane alkaloid natural products, isoschizogaline, and isochizogamine, whose ACs have not previously been determined. The ACs of naturally occurring (2)-isoschizogaline and (2)-isoschizog- amine, are both determined definitively to be 2R ,7 R ,2 0S ,2 1S. Chirality 20:454-470, 2008. V C 2007 Wiley-Liss, Inc.
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determination of the absolute configuration of a chiral oxadiazol 3 one calcium channel blocker resolved using chiral chromatography via concerted density functional theory calculations of its vibrational circular dichroism electronic circular dichro
Journal of Organic Chemistry, 2007Co-Authors: P J Stephens, F J Devlin, Alessia Ciogli, Domenico Spinelli, Francesco Gasparrini, Barbara CosimelliAbstract:The chiral oxadiazol-3-one 2 has recently been shown to exhibit myocardial calcium entry channel blocking activity, substantially higher than that of diltiazem. To determine the enantioselectivity of this activity, the enantiomers of 2 have been resolved using chiral chromatography. The absolute configuration (AC) of 2 has been determined by comparison of density functional theory (DFT) calculations of its vibrational circular dichroism (VCD) spectrum, electronic circular dichroism (ECD) spectrum, and Optical Rotation (OR) to experimental VCD, ECD, and OR data. All three chirOptical properties yield identical ACs; the AC of 2 is unambiguously determined to be S(+)/R(−).
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determination of the absolute configurations of natural products via density functional theory calculations of vibrational circular dichroism electronic circular dichroism and Optical Rotation the schizozygane alkaloid schizozygine
Journal of Organic Chemistry, 2007Co-Authors: P J Stephens, F J Devlin, Jianjung Pan, Marie Urbanova, Josef HajicekAbstract:The development of density functional theory (DFT) methods for the calculation of vibrational circular dichroism (VCD), electronic circular dichroism (ECD), and transparent spectral region Optical Rotation (OR) has revolutionized the determination of the absolute configurations (ACs) of chiral molecules using these chirOptical properties. We report the first concerted application of DFT calculations of VCD, ECD, and OR to the determination of the AC of a natural product whose AC was previously undetermined. The natural product is the alkaloid schizozygine, isolated from Schizozygia caffaeoides. Comparison of DFT calculations of the VCD, ECD, and OR of schizozygine to experimental data leads, for each chirOptical technique, to the AC 2R,7S,20S,21S for the naturally occurring (+)-schizozygine. Three other alkaloids, schizogaline, schizogamine, and 6,7-dehydro-19beta-hydroxyschizozygine, have also been isolated from S. caffaeoides and shown to have structures closely related to schizozygine. Assuming a common biosynthetic pathway, their ACs are defined by that of schizozygine.
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determination of absolute configuration using density functional theory calculations of Optical Rotation and electronic circular dichroism chiral alkenes
Journal of Organic Chemistry, 2006Co-Authors: P J StephensAbstract:In principle, the absolute configuration (AC) of a chiral molecule can be deduced from its Optical Rotation (OR) and/or its electronic circular dichroism (ECD). In practice, this requires reliable methodologies for predicting OR and ECD. The recent application of ab initio time-dependent density functional theory (TDDFT) to the calculation of transparent spectral region OR and ECD has greatly enhanced the reliability with which these phenomena can be predicted. TDDFT calculations of OR and ECD are being increasingly utilized in determining ACs. Nevertheless, such calculations are not perfect, and as a result, ACs determined are not 100% reliable. In this paper, we examine the reliability of the TDDFT methods in the case of chiral alkenes. Sodium d line specific Rotations, [α]D, are predicted for 26 conformationally rigid alkenes of known AC, ranging in size from 5 to 20 C atoms, and with [α]D values in the range of 0−500. The mean absolute deviation of predicted [α]D values from experimental values is 28....
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determination of the absolute configurations of natural products via density functional theory calculations of Optical Rotation electronic circular dichroism and vibrational circular dichroism the cytotoxic sesquiterpene natural products quadrone suberosenone suberosanone and suberosenol a acetate
Journal of Natural Products, 2006Co-Authors: P J Stephens, F J Devlin, David M Mccann, A B SmithAbstract:The determination of the absolute configurations (ACs) of chiral molecules using the chirOptical techniques of Optical Rotation (OR), electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) has been revolutionized by the development of density functional theory (DFT) methods for the prediction of these properties. Here, we demonstrate the significance of these advances for the stereochemical characterization of natural products. Time-dependent DFT (TDDFT) calculations of the specific Rotations, [α]D, of four cytotoxic natural products, quadrone (1), suberosenone (2), suberosanone (3), and suberosenol A acetate (4), are used to assign their ACs. TDDFT calculations of the ECD of 1 are used to assign its AC. The VCD spectrum of 1 is reported and also used, together with DFT calculations, to assign its AC. The ACs of 1 derived from its [α]D, ECD, and VCD are identical and in agreement with the AC previously determined via total synthesis. The previously undetermined ACs of 2−4, derived f...
Valeriy V Yashchuk - One of the best experts on this subject based on the ideXlab platform.
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detection of radio frequency magnetic fields using nonlinear magneto Optical Rotation
Physical Review A, 2007Co-Authors: M P Ledbetter, Dmitry Budker, Szymon Pustelny, S M Rochester, Victor M Acosta, Valeriy V YashchukAbstract:We describe a room-temperature alkali-metal atomic magnetometer for detection of small, high-frequency magnetic fields. The magnetometer operates by detecting Optical Rotation due to the precession of an aligned ground state in the presence of a small oscillating magnetic field. The resonance frequency of the magnetometer can be adjusted to any desired value by tuning the bias magnetic field. Based on experimentally measured signal-to-noise ratio, we demonstrate a sensitivity of $100\phantom{\rule{0.3em}{0ex}}\mathrm{pG}∕\sqrt{\mathrm{Hz}}$ (rms) in a $3.5\text{\ensuremath{-}}\mathrm{cm}$-diameter paraffin coated cell. Assuming detection at the photon shot-noise limit, we project a sensitivity as low as $25\phantom{\rule{0.3em}{0ex}}\mathrm{pG}∕\sqrt{\mathrm{Hz}}$ (rms).
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nonlinear magneto Optical Rotation with frequency modulated light in the geophysical field range
Physical Review A, 2006Co-Authors: Victor M Acosta, Dmitry Budker, W Gawlik, Szymon Pustelny, Jerzy Zachorowski, S M Rochester, D Jackson F Kimball, M P Ledbetter, D C Hovde, Valeriy V YashchukAbstract:Recent work investigating resonant nonlinear magneto-Optical Rotation (NMOR) related to long-lived $({\ensuremath{\tau}}_{\mathrm{rel}}\ensuremath{\sim}1\mathrm{s})$ ground-state atomic coherences has demonstrated potential magnetometric sensitivities exceeding ${10}^{\ensuremath{-}11}\phantom{\rule{0.3em}{0ex}}\mathrm{G}∕\sqrt{\mathrm{Hz}}$ for small $(\ensuremath{\lesssim}1\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{G}$) magnetic fields. In the present work, NMOR using frequency-modulated light (FM NMOR) is studied in the regime where the longitudinal magnetic field is in the geophysical range$(\ensuremath{\sim}500\mathrm{mG})$, of particular interest for many applications. In this regime a splitting of the FM NMOR resonance due to the nonlinear Zeeman effect is observed. At sufficiently high light intensities, there is also a splitting of the FM NMOR resonances due to ac Stark shifts induced by the Optical field, as well as evidence of alignment-to-orientation conversion type processes. The consequences of these effects for FM-NMOR-based atomic magnetometry in the geophysical field range are considered.
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pump probe nonlinear magneto Optical Rotation with frequency modulated light
Physical Review A, 2006Co-Authors: Szymon Pustelny, Valeriy V Yashchuk, W Gawlik, S M Rochester, D Jackson F Kimball, Dmitry BudkerAbstract:Specific types of atomic coherences between Zeeman sublevels can be generated and detected using a method based on nonlinear magneto-Optical Rotation with frequency-modulated light. Linearly polarized, frequency-modulated light is employed to selectively generate ground-state coherences between Zeeman sublevels for which m=2 and m=4 in 85 Rb and 87 Rb atoms, and additionally m=6 in 85 Rb. The atomic coherences are detected with a separate, unmodulated probe light beam. Separation of the pump and probe beams enables independent investigation of the processes of creation and detection of the atomic coherences. With the present technique the transfer of the Zeeman coherences, including high-order coherences, from excited to ground state by spontaneous emission has been observed.
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microwave transitions and nonlinear magneto Optical Rotation in anti relaxation coated cells
Physical Review A, 2005Co-Authors: Dmitry Budker, Derek Jackson F Kimball, Szymon Pustelny, L Hollberg, J Kitching, Valeriy V YashchukAbstract:Using laser Optical pumping, widths and frequency shifts are determined for microwave transitions between ground-state hyperfine components of {sup 85}Rb and {sup 87}Rb atoms contained in vapor cells with alkane anti-relaxation coatings. The results are compared with data on Zeeman relaxation obtained in nonlinear magneto-Optical Rotation (NMOR) experiments, a comparison important for quantitative understanding of spin-relaxation mechanisms in coated cells. By comparing cells manufactured over a forty-year period we demonstrate the long-term stability of coated cells, an important property for atomic clocks and magnetometers.
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nonlinear magneto Optical Rotation of frequency modulated light resonant with a low j transition
Physical Review A, 2004Co-Authors: Yu P Malakyan, Dmitry Budker, Derek Jackson F Kimball, S M Rochester, Valeriy V YashchukAbstract:A low-light-power theory of nonlinear magneto-Optical Rotation of frequency-modulated light resonant with a J=1{yields}J{sup '}=0 transition is presented. The theory is developed for a Doppler-free transition and then modified to account for Doppler broadening and velocity mixing due to collisions. The results of the theory are shown to be in qualitative agreement with experimental data obtained for the rubidium D1 line.
Bingui Wang - One of the best experts on this subject based on the ideXlab platform.
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prenylated phenol and benzofuran derivatives from aspergillus terreus en 539 an endophytic fungus derived from marine red alga laurencia okamurai
Marine Drugs, 2019Co-Authors: Honglei Li, Xiaoming Li, Suiqun Yang, Linghong Meng, Xin Li, Bingui WangAbstract:Three new prenylated phenol derivatives, terreprenphenols A–C (1–3), along with four known related compounds (4–7), were isolated from Aspergillus terreus EN-539, an endophytic fungus obtained from the marine red alga Laurencia okamurai. The structures of these compounds were established by extensive analysis of 1D/2D NMR data, mass spectrometric data, and Optical Rotation (OR). The corresponding relationship between absolute configuration and Optical Rotation for known compounds anodendroic acid (4) and asperterreusine C (5) was ambiguous in literature, and their absolute configurations were therefore discussed and confirmed for the first time by time-dependent density functional (TDDFT) ECD and OR calculations. Compounds 1–7 inhibited some common aquatic bacteria with MIC values ranging from 2 to 64 μg/mL.
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prenylated phenol and benzofuran derivatives from aspergillus terreus en 539 an endophytic fungus derived from marine red alga laurencia okamurai
Marine Drugs, 2019Co-Authors: Suiqun Yang, Linghong Meng, Bingui WangAbstract:Three new prenylated phenol derivatives, terreprenphenols A–C (1–3), along with four known related compounds (4–7), were isolated from Aspergillus terreus EN-539, an endophytic fungus obtained from the marine red alga Laurencia okamurai. The structures of these compounds were established by extensive analysis of 1D/2D NMR data, mass spectrometric data, and Optical Rotation (OR). The corresponding relationship between absolute configuration and Optical Rotation for known compounds anodendroic acid (4) and asperterreusine C (5) was ambiguous in literature, and their absolute configurations were therefore discussed and confirmed for the first time by time-dependent density functional (TDDFT) ECD and OR calculations. Compounds 1–7 inhibited some common aquatic bacteria with MIC values ranging from 2 to 64 μg/mL.
Jochen Autschbach - One of the best experts on this subject based on the ideXlab platform.
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temperature dependence of the Optical Rotation in six bicyclic organic molecules calculated by vibrational averaging
ChemPhysChem, 2007Co-Authors: Brendan C Mort, Jochen AutschbachAbstract:The vibrational corrections and the temperature dependence of the specific Rotation of six rigid organic molecules (alpha-pinene, beta-pinene, cis-pinane, camphene, camphor, and fenchone) were calculated at three wavelengths using hybrid time-dependent density functional theory (TDDFT). A technique for calculating the temperature dependence of the vibrational average of a molecular property has been applied to obtain the specific Rotation of the molecules as a function of temperature. For cases in which accurate equilibrium Optical Rotations can be obtained as a "base value," and for which there is little effect from solvation, accurate predictions of the trends in the temperature-dependence of the specific Rotations can be calculated. For other cases, the method can be used to extract purely vibrational contributions to the overall temperature dependence of Optical Rotation.
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Temperature dependence of the Optical Rotation of fenchone calculated by vibrational averaging.
The journal of physical chemistry. A, 2006Co-Authors: Brendan C Mort, Jochen AutschbachAbstract:On the basis of vibrational averaging, the temperature dependence of the Optical Rotation for fenchone has been calculated using TDDFT with the B3LYP hybrid functional at three wavelengths. The results show that very good agreement is obtained between theory and experiment. It is concluded that temperature-dependent vibrational effects are likely to account for much of the observed temperature dependence in Optical Rotation exhibited by rigid organic molecules in case there is only a weak temperature-dependent interaction with the solvent.
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calculation of origin independent Optical Rotation tensor components in approximate time dependent density functional theory
Journal of Chemical Physics, 2006Co-Authors: Mykhaylo Krykunov, Jochen AutschbachAbstract:We outline an implementation of the origin-independent Optical Rotation tensor, which includes electric dipole-magnetic dipole and electric dipole-electric quadrupole polarizability. The method is based on approximate time-dependent density functional theory. We utilize time-periodic magnetic-field-dependent basis functions as well as a modified velocity-gauge formulation of dynamic polarizability tensors in order to obtain a gauge-origin independence. To ensure gauge-origin independence of the results within a given numerical accuracy, density fit coefficient derivatives are employed. A damping constant has been introduced into the linear response equations to treat both resonance and nonresonance regions of Optical activity. We present calculations for trans-2,3-dimethyloxirane and derivatives thereof as well as calculations for androst-4,17-dien-3-one. In the Appendix, we derive the equivalence between the common-gauge origin and gauge-including atomic orbitals formulations for the Optical Rotation ten...
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time dependent density functional calculations of Optical rotatory dispersion including resonance wavelengths as a potentially useful tool for determining absolute configurations of chiral molecules
Journal of Physical Chemistry A, 2006Co-Authors: Jochen Autschbach, Lasse Jensen, George C Schatz, Mykhaylo KrykunovAbstract:The Optical Rotations for six organic molecules (verbenone, fenchone, camphor, nopinone, Troger's base, dimethyl-cyclopropane) and the transition metal complex [Co(en)3]3+ were calculated as a function of wavelength using time-dependent density functional theory (TDDFT). In the calculations, a realistic behavior of the Optical Rotation in the vicinity of an electronic transition was obtained by using a phenomenological damping parameter of the order of 0.2 eV (0.007 au). In comparison with experiment, for the molecules studied here the sign and order of magnitude of the Optical Rotation as well as the excitation energies were reasonably well reproduced in most computations. These findings apply to the investigated wavelength ranges typically between about 200 and 650 nm even when using comparatively small basis sets. Such calculations might therefore routinely be applied to help assigning the absolute configurations of chiral molecules. Supplementary calculations of the circular dichroism (CD) and compari...