Hyperfine Constants Research Articles

Absolute frequency measurements on the 5s5p3P0 → 5s6d3D1 transition in strontium

We report the first absolute frequency measurements for the 5s5p3P0→5s6d3D1 transition at 394 nm for all the stable strontium isotopes by utilizing repumping induced spectroscopy in a magneto-optical trap. Absolute transition frequency is measured to be 760524409251(25) kHz for Sr88. With reference to Sr88, the isotope shifts are measured to be 91052(35), 54600(33), and 51641(28) kHz for Sr84, Sr86, and Sr87, respectively. We calculate the hyperfine constants A and B for the fermionic isotope Sr87 at kHz level. Furthermore, we perform King plot analysis by combining isotope shifts on the 689-nm transition to our data. Published by the American Physical Society 2024

Measurement of transition frequencies and hyperfine constants of molecular iodine at 520.2 nm

We measured the transition frequencies of the hyperfine components in the four lines (P(34) 39-0, R(36) 39-0, P(33) 39-0, and R(35) 39-0) of the B-X transitions of molecular iodine at 520.2 nm. The 520.2 nm laser was generated by wavelength-converting the output of a 1560.6 nm external-cavity diode laser using a dual-pitch periodically poled lithium niobate (PPLN) waveguide. The frequencies were measured by counting the heterodyne beats between the laser stabilized at the frequencies of the hyperfine components and a frequency comb synchronized with a hydrogen maser. We determined the transition frequencies of the a1 components with relative uncertainties of 1×10−11; the uncertainty was limited by the impurity of the molecular iodine in the cell. From the measured hyperfine splitting frequencies, we calculated the hyperfine constants of these four transitions to obtain the rotational dependence of the excited-state hyperfine constants.

Optical Frequency References at 1542 nm: Precision Spectroscopy of the R(106)50-0, R(100)49-0, R(84)47-0, R(59)45-0, P(82)47-0, and P(71)46-0 Lines of 127I2 at 514 nm

Frequency-stabilized lasers are fundamental topics in research relating to optical frequency and wavelength standards. The absolute frequencies and hyperfine structures of the R(106)50-0, R(100)49-0, R(84)47-0, R(59)45-0, P(82)47-0, and P(71)46-0 lines of molecular iodine (127I2) at 514 nm were measured using a frequency-stabilized laser based on modulation transfer spectroscopy. The hyperfine splitting of each line was fitted to a four-term Hamiltonian with an uncertainty of several kilohertz to obtain the hyperfine constants for the line. A total of 97 hyperfine transitions of the six lines were measured with an uncertainty of 5.6 kHz (fractionally 9.6 × 10−12). They can provide new optical frequency references for telecommunication and other applications.

Large-scale multiconfiguration Dirac-Hartree-Fock calculations of atomic data, Landé gj -factors and hyperfine constants of the neutral Rn-211 isotope

We computed the atomic data of ns[K]J ( n = 7, 8, 9), np[K]J ( n = 7, 8, 9), nd[K]J ( n = 6, 7, 8, 9), and nf[K]J ( n = 5, 6, 7, 8) and 5g[K]J autoionized Rydberg spectra of the neutral radon-211 isotope. The computations are carried out by using the Multiconfiguration Dirac-Hartree-Fock method (MCDHF) together with the relativistic configuration (RCI) approach. The convergence of the obtained results is monitored by incorporating relativistic electron-electron correlation, the Breit-interaction effect, self-energy, and vacuum-polarization corrections. As a result, we acquired the energy levels, transition rates, oscillator strengths, Landé gJ -factors and magnetic dipole hyperfine constants. The transition parameters between the levels belonging to different series are computed for all allowed electric dipole transition selection rules. The present results are in very good agreement with other experimental and theoretical data available in the literature database. The present data could be useful in predicting spectral lines of radon via astrophysics and stellar spectroscopy.

Isotope shifts in electron affinities and in binding energies of Pb and hyperfine structure of 207Pb.

The isotope shifts in electron affinities of Pb were measured by Walter et al. [Phys. Rev. A 106, L010801 (2022)] to be -0.002(4) meV for 207-208Pb and -0.003(4) meV for 206-208Pb by scanning the threshold of the photodetachment channel Pb-(S3/2◦4) - Pb (3P0), while Chen and Ning reported 0.015(25) and -0.050(22) meV for the isotope shifts on the binding energies measured relative to 3P2 using the SEVI method [J. Chem. Phys. 145, 084303 (2016)]. Here we revisited these isotope shifts by using our second-generation SEVI spectrometer and obtained -0.001(15) meV for 207-208Pb and -0.001(14) meV for 206-208Pb, respectively. In order to aid the experiment by theory, we performed the first abinitio theoretical calculations of isotope shifts in electron affinities and binding energies of Pb, as well as the hyperfine structure of 207Pb-, by using the MCDHF and RCI methods. The isotope shifts in electron affinities of 207-208Pb and 206-208Pb are -0.0023(8) and -0.0037(13) meV for the 3P0 channel, respectively, in good agreement with Walter et al.'s measurements. The isotope shifts in binding energies relative to 3P1,2, -0.0015(8) and -0.0026(13) meV for 207-208Pb and 206-208Pb, respectively, are compatible with the present measurements. The hyperfine constant for the ground state of 207Pb- obtained by the present calculations, A(S3/2◦4)=-1118 MHz, differs by a factor of 3 from the previous estimation by Bresteau et al. [J. Phys. B: At., Mol. Opt. Phys. 52, 065001 (2019)]. The reliability is supported by the good agreement between the theoretical and experimental hyperfine parameters of 209Bi.

Spectroscopic study of the 4f76s2 8 S7/2∘ – 4f7(8S°) 6s6p(1P°) 8P5/2,7/2 transitions in neutral europium-151 and europium-153: absolute frequency and hyperfine structure

We report on spectroscopic measurements on the 4f76s28S7/2∘−4f7(8S∘)6s6p(1P∘)8P5/2,7/2 transitions at 466.32 nm and 462.85 nm, respectively, in neutral europium-151 and europium-153. The center of gravity frequencies for the 151 and 153 isotopes for both transitions are reported for the first time using saturated absorption spectroscopy. For the 6s6p(1P∘)8P5/2 state, the center of gravity frequencies were found to be 642,894,493.3(4) MHz and 642,891,693.3(9) MHz for the 151 and 153 isotopes, respectively. The hyperfine constants for the upper state were found to be A(151)=−157.01(3)MHz, B(151)=74.5(4)MHz and A(153)=−69.43(14)MHz, B(153)=191.0(26)MHz. These hyperfine values are all consistent with previously published results except for B(151) that has a small discrepancy. The isotope shift was found to be 2799.54(20) MHz, a small discrepancy with previously published results. For the 6s6p(1P∘)8P7/2 state, the center of gravity frequencies were found to be 647,708,930.6(6) MHz and 647,705,958.4(26) MHz for the 151 and 153 isotopes, respectively. The hyperfine constants for the upper state were found to be A(151)=−218.66(4)MHz, B(151)=−293.4(8)MHz and A(153)=−97.15(13)MHz, B(153)=−750(3)MHz. These values are all consistent with previously published results except for A(151) that has a small discrepancy. The isotope shift was found to be 2972.8(5) MHz, a small discrepancy with previously measured results.

Laser spectroscopy of triply charged 229Th isomer for a nuclear clock.

Thorium-229 (229Th) possesses an optical nuclear transition between the ground state (229gTh) and low-lying isomer (229mTh). A nuclear clock based on this nuclear-transition frequency is expected to surpass existing atomic clocks owing to its insusceptibility to surrounding fields1-5. In contrast to other charge states, triply charged 229Th (229Th3+) is the most suitable for highly accurate nuclear clocks because it has closed electronic transitions that enable laser cooling, laser-induced fluorescence detection and state preparation of ions1,6-8. Although laser spectroscopic studies of 229Th3+ in the nuclear ground state have been performed8, properties of 229mTh3+, including its nuclear decay lifetime that is essential to specify the intrinsic linewidth of the nuclear-clock transition, remain unknown. Here we report the trapping of 229mTh3+ continuously supplied by a 233U source and the determination of nuclear decay half-life of the isolated 229mTh3+ to be through nuclear-state-selective laser spectroscopy. Furthermore, by determining the hyperfine constants of 229mTh3+, we reduced the uncertainty of the sensitivity of the 229Th nuclear clock to variations in the fine-structure constant by a factor of four. These results offer key parameters for the 229Th3+ nuclear clock and its applications in the search for new physics.

Automatic Detection of Nuclear Spins at Arbitrary Magnetic Fields via Signal-to-Image AI Model.

Quantum sensors leverage matter's quantum properties to enable measurements with unprecedented spatial and spectral resolution. Among these sensors, those utilizing nitrogen-vacancy (NV) centers in diamond offer the distinct advantage of operating at room temperature. Nevertheless, signals received from NV centers are often complex, making interpretation challenging. This is especially relevant in low magnetic field scenarios, where standard approximations for modeling the system fail. Additionally, NV signals feature a prominent noise component. In this Letter, we present a signal-to-image deep learning model capable of automatically inferring the number of nuclear spins surrounding a NV sensor and the hyperfine couplings between the sensor and the nuclear spins. Our model is trained to operate effectively across various magnetic field scenarios, requires no prior knowledge of the involved nuclei, and is designed to handle noisy signals, leading to fast characterization of nuclear environments in real experimental conditions. With detailed numerical simulations, we test the performance of our model in scenarios involving varying numbers of nuclei, achieving an average error of less than 2kHz in the estimated hyperfine constants.

Millimeter and Submillimeter Spectroscopy of the Deuterated Molecular Ion SD+

Seven rotational and fine-structure transitions of the deuterated molecular ion SD+ in the X 3Σ− ground electronic state have been measured in the 271–863 GHz region in the laboratory. This ion has been produced by direct-current glow discharge using a mixture of D2S and argon in a free space cell in a temperature range of −140°C to −160°C. The rotational, centrifugal distortion, spin–spin interaction, and hyperfine constants have been determined; the standard deviation of the residuals in the fitting is 109 kHz. The set of obtained spectroscopic parameters provides a list of accurate submillimeter rest frequencies of SD+ for astronomical detection. We have investigated lines of SD+ toward the quasar PKS 1830-211 using the Atacama Large Millimeter/submillimeter Array archive, as the z = 0.89 molecular absorber exists in front of this quasar. A data set covering the 297 GHz region includes the N J = 23–12 transition at 561 GHz due to redshift, providing an upper limit of the column density N tot = 3 × 1012 cm−2 for SD+.

Computation of hyperfine multiplet oscillator strengths in Tantalum atom

BackgroundThe electronic transitions between two fine levels depend on the transition probability. The transition probability depends on spectral line strength and oscillator strength. The oscillator strength depends on the number of oscillators and their energies. In this research, we will find the oscillator strengths of hyperfine multiplets of the Tantalum atom. The oscillator strength of hyperfine multiplet investigation aims to enhance our understanding of Tantalum's spectral characteristics. This work provides valuable information in the spectroscopy of material, atomic/molecular, and astrophysics.ResultFourier transform spectra from ultraviolet to far infrared regions have been obtained from TUGRAZ. Fourier transform spectra give the most reliable position of the wavelength of hyperfine multiplets. The Fourier transform spectra of Tantalum contain thousands of Tantalum I and II spectral lines. Each spectral line can be characterized by its upper and lower levels and corresponding angular momenta and hyperfine constants. These properties of the spectral lines were collected from the literature. Hyperfine multiplets for each fine structure were calculated, and they revealed their spectroscopic behavior with high precision.ConclusionIn this study, Tantalum's hyperfine multiplet oscillator strength was calculated using advanced computational techniques to address its atomic structure. The fine structure “gf” values were obtained from literature, and intensities of the multiplets were determined. They combined with the gf values to calculate the oscillator strengths of the hyperfine multiplets.

A perturbed energy level of the holmium atom

This study focuses on two lines of atomic holmium for which standard hyperfine structure analysis could not be performed. The lines were studied by laser-induced fluorescence spectroscopy using a Ti-sapphire laser. Usually, the hyperfine structure of spectral lines is described by the well-known Casimir formula. However, this was not possible in the analysis of these two lines. The common feature of these two lines is that their upper energy levels are identical. In this study, hyperfine structure analyses were performed by considering a perturbation in the hyperfine splitting of the upper energy level of both lines. Shifts were introduced for the hyperfine sub-levels with F = 4 to 7 of the perturbed level, with the help of which the positions of all components of both laser lines could be satisfactorily explained. The same behaviour was found for three other spectral lines present in the Fourier transform spectrum, which are connected to the same perturbed upper energy level. The perturbation must be caused by a hitherto unknown energy level of odd parity with small J -value. The energy, J - quantum number and hyperfine constant A of this level were estimated.

Precision spectroscopy of iodine absorption lines near the 1S0-3P2 transition of Yb atoms at 507 nm

We performed Doppler-free spectroscopy on the P(40)52-0 and P(52)53-0 lines of molecular iodine (127I2) near the 1S0-3P2 metastable transition of Yb at 507 nm. The frequency instability of an external-cavity diode laser locked to the observed hyperfine transitions of the 127I2 lines reached a level below 1.0 × 10−12, at the average time τ of the measurement of >10 s. The absolute frequency of the laser locked to the hyperfine transitions was measured with an uncertainty of 8 kHz (fractionally 1.4 × 10−11) using an optical frequency comb. The hyperfine transition intervals were fitted to a four-term Hamiltonian to validate the measurements and calculate the hyperfine constants of the iodine lines. The observed 30 hyperfine transitions of the P(40)52-0 and P(52)53-0 lines of 127I2 can be used as optical frequency references to investigate the 1S0-3P2 transition of Yb atoms.

Investigation of the 6s6p P03−4f135d6s2 ( J=2 ) Clock Transition in Yb171 Atoms

High-precision atomic spectroscopy provides an invaluable and sensitive tool for exploring a wide range of physical questions. Here, we investigate the forbidden optical transition of the 6s6pP30−4f135d6s2 (J=2) in Y171b atoms at the wavelength of 1695 nm, which exhibits the highest sensitivity to the variation of the fine-structure constant α compared to the current neutral optical clock. We obtain high-resolution transition spectroscopy in a one-dimensional optical lattice, and the measurement of its absolute frequency achieves kHz-level accuracy. Meanwhile, several essential atomic constants are also determined, including the electric-dipole (E1) magic wavelengths, as well as the hyperpolarizabilities and tensor polarizabilities around the E1 magic wavelengths. Additionally, we derive the hyperfine constant for the J=2 state from the measured absolute frequencies 1123 252.3±2.0 kHz, providing a sixfold enhancement in the uncertainty reduction compared to the recent result. We anticipate that this work will prompt further investigation of the additional clock transition at 1695 nm in Y171b atoms. Together with the well-established S01−P03 transition, many fundamental and new physics research, such as the time variation of α, ultralight dark-matter searches, Lorentz violation, etc., will enable new bounds and measurements with unprecedented precision. Published by the American Physical Society 2024

Insights of the peroxychloroformyl radical ClC(O)OO via microwave spectrum.

The exploration of Venus has received much attention in the past and will keep growing due to the starting of the NASA DAVINCI project. To explain the extremely low O2 : CO ratio observed in Venus' atmosphere, a chlorine-initiated CO oxidation catalytic cycle has been proposed. However, relevant studies on the key intermediates, such as the peroxychloroformyl radical (ClC(O)OO), are rare. In this study, the ClC(O)OO radical was observed using Fourier-Transform Microwave (FTMW) spectroscopy under the supersonic expansion condition. Two conformers, trans-ClC(O)OO and cis-ClC(O)OO, and their chlorine isotopologues were detected. The molecular constants including the fine and hyperfine constants, were determined. Based on the experimental and the ab initio calculations, the unpaired electron is mostly located at the terminal oxygen atom, supported by the small magnetic hyperfine constants of chlorine. In addition, the angles between the Cl-C bond and the a-axis of the trans-35ClC(O)OO and trans-37ClC(O)OO are similar, but these angles are different for cis-ClC(O)OO, making the quadrupole coupling tensors in the inertial axes disagree with the ratio of the quadrupole moments of 35Cl and 37Cl. Finally, we concluded that the ClC(O)OO radicals should behave similarly to other peroxyl radicals, as assumed in the current photochemical model of Venus.

Fourier-transform microwave spectroscopy of the ClSO radical.

Pure rotational transitions of the ClSO radical have been observed by Fourier-transform microwave spectroscopy. a-type and b-type transitions, for both 35Cl and 37Cl isotopologues, were detected, and the observed very complicated fine and hyperfine components were assigned well. The intensities of the observed spectra of the two isotopologues correspond to the ratio of the isotope abundances of 35Cl and 37Cl. A total of 21 molecular constants were determined precisely for both 35ClSO and 37ClSO, including the rotational constants, centrifugal distortion constants, electronic spin-rotation constants, nuclear spin-rotation constants, magnetic hyperfine constants, and quadrupole coupling constants of chlorine. The molecular constants show ClSO to have the 2A'' electronic ground state with an out-of-plane unpaired electron. The spin density of the chlorine atom is about 10.6%, which is similar to that of the fluorine atom for FSO, about 8%. Results of the ClSO radical are compared with those of other triatomic radicals with similar structures, the XSS, XSO, and XOO radicals with X = H, F, and Cl, leading to a conclusion that the ClSO radical is more like FSO, but fairly different from the FOO and ClOO radicals.

Accurate calculation of hyperfine-induced 5d6s <sup>3</sup>D<sub>1,3</sub>→6s<sup>2</sup> <sup>1</sup>S<sub>0</sub> E2 transitions and hyperfine constants of ytterbium atoms

The parity violation effects via the <inline-formula><tex-math id="M14">\begin{document}$ {\mathrm{5d6s\; {^3D_1} \to 6s^2 \; {^1S_0}}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M14.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M14.png"/></alternatives></inline-formula> transition have been extensively investigated in ytterbium atoms. However, the M1 transition between the excitation state <inline-formula><tex-math id="M15">\begin{document}$ {\mathrm{5d6s\; {^3D_1}}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M15.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M15.png"/></alternatives></inline-formula> and the ground state <inline-formula><tex-math id="M16">\begin{document}$ {\mathrm{6s^2 \; {^1S_0}}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M16.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M16.png"/></alternatives></inline-formula>, as well as the hyperfine-induced E2 transition, significantly affects the detection of parity violation signal. Therefore, it is imperative to obtain the accurate transition probabilities for the M1 and hyperfine-induced E2 transitions between the excitation state <inline-formula><tex-math id="M17">\begin{document}${\mathrm{ 5d6s\; {^3D_1} }}$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M17.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M17.png"/></alternatives></inline-formula> and the ground state <inline-formula><tex-math id="M18">\begin{document}$ {\mathrm{6s^2\; {^1S_0}}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M18.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M18.png"/></alternatives></inline-formula>. In this work, we use the multi-configuration Dirac-Hartree-Fock theory to precisely calculate the transition probabilities for the <inline-formula><tex-math id="M19">\begin{document}${\mathrm{ 5d6s \; {^3D_1} \to 6s^2 \; {^1S_0} }}$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M19.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M19.png"/></alternatives></inline-formula> M1 and hyperfine-induced <inline-formula><tex-math id="M20">\begin{document}${\mathrm{ 5d6s \; ^3D_{1,3} \to 6s^2 \; {^1S_0} }}$\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M20.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M20.png"/></alternatives></inline-formula> E2 transitions. We extensively analyze the influences of electronic correlation effects on the transition probabilities according to our calculations. Furthermore, we analyze the influences of different perturbing states and various hyperfine interactions on the transition probabilities. The calculated hyperfine constants of the e <inline-formula><tex-math id="M21">\begin{document}$ {\mathrm{^3D_{1,2,3}}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M21.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M21.png"/></alternatives></inline-formula> and <inline-formula><tex-math id="M22">\begin{document}${\mathrm{ ^1D_2}} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M22.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M22.png"/></alternatives></inline-formula> states accord well with experimental measurements, validating the rationality of our computational model. By combining experimentally measured hyperfine constants with the theoretically derived electric field gradient of the extra nuclear electrons at the nucleus, we reevaluate the nuclear quadrupole moment of the <inline-formula><tex-math id="M23">\begin{document}$ ^{173} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M23.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M23.png"/></alternatives></inline-formula>Yb nucleus as <inline-formula><tex-math id="M24">\begin{document}$ Q = 2. 89(5) \;\rm {b} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M24.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240028_M24.png"/></alternatives></inline-formula>, showing that our result is in excellent agreement with the presently recommended value.

Fourier-transform microwave spectroscopy of the ClSS radical.

The ClSS radical is one of the members of the XSS, XSO and XOO (X = H, F, Cl) radicals. It was studied by Fujitake et al. using millimeter- and sub-millimeter wave spectroscopy, where no hyperfine structure was resolved. As the last piece of this series of radicals, it is important to determine the fine and hyperfine constants of the ClSS radical precisely using FTMW spectroscopy. Different from the case of the ClSO radical with the unpaired electron mainly occupying the S atom at the center, the unpaired electron of the ClSS radical mainly occupies the pc orbital of the terminal S atom. Despite this difference, the investigation of the fine and hyperfine structures of the ClSS radical made us confirm that the XSS and XSO radicals share characteristics in common, but they are quite different from the XOO radicals.

EPR INVESTIGATIONS OF DPPH AND MN(II)CL2/H2O

EPR (Electron paramagnetic resonance) spectroscopies of DPPH (DiPhenylPicrylHydrazyl) and Mn(II)Cl2/H2O were carried out at different temperatures and the spectra were analyzed using EPR theory and spectroscopic techniques. The g-values and hyperfine constants were determined from the spectra and were compared to previously established data in other experiments in this field and thus analyzed.

Variation of the Quadrupole Hyperfine Structure and Nuclear Radius due to an Interaction with Scalar and Axion Dark Matter.

Atomic spectroscopy is used to search for the space-time variation of fundamental constants which may be due to an interaction with scalar and pseudoscalar (axion) dark matter. In this Letter, we study the effects that are produced by the variation of the nuclear radius and electric quadrupole moment. The sensitivity of the electric quadrupole hyperfine structure to both the variation of the quark mass and the effects of dark matter exceeds that of the magnetic hyperfine structure by 1-2 orders of magnitude. Therefore, the measurement of the variation of the ratio of the electric quadrupole and magnetic dipole hyperfine constants is proposed. The sensitivity of the optical clock transitions in the Yb^{+} ion to the variation of the nuclear radius allows us to extract, from experimental data, limits on the variation of the hadron and quark masses, the QCD parameter θ and the interaction with axion dark matter.

EPR Spectrum Analysis of DPPH and MnCl2

This paper presents the findings of electron paramagnetic resonance (EPR) spectroscopy experiments conducted on two different samples: 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Manganese Chloride (MnCl2) dissolved in H2O. The experiments were conducted at Dr. D. Petasis EPR lab located in Allegheny College, Meadville, PA, USA. A Varian X-Band spectrometer was utilized for the analysis of the EPR absorption spectra. The primary objective was to determine the g-values and hyperfine structure of the two samples, which can be crucial in characterizing their electronic properties. The g-values obtained for both DPPH and MnCl2 were found to be remarkably close to the theoretically calculated values, suggesting the high accuracy and success of the experiments. This agreement validates the reliability of the EPR measurements and demonstrates the precision of the instruments and experimental procedures employed. For the MnCl2 sample, a hyperfine structure with 6 visible EPR lines was observed. By analyzing the number of EPR lines, the nuclear spin of the Mn(II) ion was determined to be I = 5/2, consistent with the expected value for Mn(II). The hyperfine constant (A) was also calculated from the field position differences between adjacent lines, providing further insights into the sample's magnetic properties. Comparisons were made between the obtained g-values and hyperfine constant with the expected values for Mn(II) in the literature, confirming the accuracy of the measurements and reinforcing the credibility of the experimental data. Overall, the EPR spectroscopy experiments conducted on DPPH and MnCl2 in H2O have provided valuable information about the electronic and magnetic properties of these paramagnetic materials. The results demonstrate the effectiveness of EPR spectroscopy as a powerful experimental technique for investigating various bio-chemical samples and understanding the effects of solvents on the EPR spectra of compounds. The close agreement between the experimental and theoretical values for the g-factors and hyperfine constants reinforces the reliability of the data obtained from the EPR experiments.