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single crystal
摘要： We have investigated the hyperfine structure in high-resolution broadband optical absorption spectra of a strongly diluted paramagnet 7LiYF4 : Ho3+ (0.1 at. %) in external magnetic fields parallel to the tetragonal symmetry axis of the crystal. Anticrossings in the hyperfine spectral pattern were observed. It is the first direct observation of the hyperfine level anticrossings in optical spectra. Analysis of the spectral envelopes corresponding to transitions between the electron-nuclear sublevels of crystal-field non-Kramers doublets and singlets of the Ho3+ ions, based on the microscopic model of the electronic 4f 10 configuration, allowed us to retrieve information on the hyperfine structure of electronic singlets, nuclear quadroupole interactions, and random lattice strains.
关键词： LiYF4:Ho3+,hyperfine structure,hyperfine interactions,crystal-field,random strains,optical spectra,magnetic fields,anticrossings
更新于2025-09-23 15:23:52
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Hyperfine structure and 2s-2p transition in C-like Fe, Co and Ni
摘要： Energy levels, hyperfine structure and 2s-2p radiative transition processes of C-like Fe, Co and Ni are studied by performing multiconfiguration Dirac–Hartree–Fock method using the fully relativistic codes GRASP2K. Electron correlation effect on the energies, hyperfine structure constants and radiative transition rates are investigated in detail. Influences of Breit and quantum electrodynamics (QED) effect on energies are studied. Good agreements are found between the results in this work and experimental data. The radiative spectra of the excited states 1s22s2p3 and 1s22p4 of C-like Fe, Co and Ni may provide theoretical support for further experimental study. Since Fe, Co and Ni are important constituent part of experimental apparatus (such as EBIT), the data in this work have important application value for experimental application.
关键词： Radiative transition,Hyperfine structure,MCDF method
更新于2025-09-23 15:22:29
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On the performance of wavelength meters: Part 1a??consequences for medium-to-high-resolution laser spectroscopy
摘要： Present-day laser-spectroscopy experiments increasingly rely on modern commercial devices to monitor, stabilize, and scan the wavelength of their probe laser. Recently, new techniques are capable of achieving unprecedented levels of precision on atomic and nuclear observables, pushing these devices to their performance limits. Considering the fact that these observables themselves are deduced from the frequency difference between specific atomic resonances, in the order of MHz–GHz, the uncertainty on the output of the device measuring the wavelength is often directly related to the final systematic uncertainty on the experimental results. Owing to its importance, the performance of several commercial wavelength meters was compared against different reference sources, including a Scanning Fabry–Pérot Interferometer (SFPI) and a frequency comb. Reproducible, wavelength- and device-dependent disagreements are observed, potentially skewing the experimental output at high precision. In this paper, a practical and relatively inexpensive wavelength meter characterization procedure is presented and validated. This method is capable of improving the precision on wavelength differences considerably depending on the device, while together with a second investigation that is published separately, (K?nig et al., in Appl Phys B, 2020), it offers a full description of the expected wavelength meter performance for users.
关键词： frequency comb,hyperfine structure,laser spectroscopy,wavelength meters,Scanning Fabry–Pérot Interferometer
更新于2025-09-23 15:21:01
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A Study of the Kinetic Parameters of Lu Laser Photoionization Scheme
摘要： Development of the laser photoionization method for obtaining 177Lu radionuclide for a medical purpose requires the knowledge of the light-saturation intensities at each stage of the Lu photoionization scheme (5d6s2 2D3/2?5d6s6p 4F5/2?5d6s7s 4D3/2?(53375 cm–1)), taking into account the used components of the hyperfine structure of transitions. The effective excitation cross sections of various hyperfine transition components for 175Lu, 176Lu, 177Lu, and 177mLu isotopes have been experimentally determined for radiations of pulsed tunable dye lasers pumped by copper-vapor lasers.
关键词： laser isotope separation,177Lu,hyperfine structure,laser photoionization
更新于2025-09-23 15:21:01
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A direct diode pumped Ti:sapphire laser with single-frequency operation for high resolution spectroscopy
摘要： A direct diode pumped continuous-wave Ti:sapphire laser (DDPTS) is presented. A bow-tie geometry with optical diode is chosen for unidirectional single-mode operation. Frequency selection is performed with a standard combination of birefringent filter and etalon. To accomplish mode-hop free frequency tuning the piezo-driven etalon is stabilized to one of the cavity modes via dither-locking method. To suppress environmental fluctuations the cavity-mode is additionally locked to an external optical cavity with low frequency drift. Feasibility of the setup for high-resolution spectroscopy is demonstrated by saturated absorption spectroscopy of the D2 line of Rubidium.
关键词： Rubidium,Stabilization,Hyperfine structure,Laser,Titanium:sapphire,Optical cavity,Beatnote
更新于2025-09-23 15:21:01
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Hyperfine structures and isotopic shifts of uranium transitions using tunable laser spectroscopy of laser ablation plumes
摘要： We report isotopic shifts and hyperfine structures of selected U transitions employing tunable spectroscopy viz: laser-induced fluorescence and laser absorption spectroscopy of laser ablation plumes. The plasmas were produced during ns laser ablation on a natural U metal target which contains 0.73% 235U. Our results show that isotopic shifts between 238U and 235U are entangled with hyperfine structures of 235U. Measurements obtained using laser-induced fluorescence are affected by the high absorbance of 238U. Time-resolved laser absorption spectroscopy is carried out for evaluating the optical absorption and estimating the hyperfine constants.
关键词： LIBS,Hyperfine structure,Laser absorption spectroscopy,Isotopic analysis,Uranium,Laser-induced fluorescence,Laser ablation,Tunable laser spectroscopy
更新于2025-09-23 15:19:57
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Features of the Formation of the Spin Polarization of an Alkali Metal at the Resolution of Hyperfine Sublevels in the 2S1/2 State
摘要： The optical orientation of the angular momenta of alkali atoms in the presence of a buffer gas (molecular nitrogen) has been studied experimentally. It has been shown that, even at a low concentration of molecular nitrogen in the cell, the excitation of 133Cs atoms from the lower hyperfine level with F = 3, which belongs to the 2S1/2 state, results in a larger amplitude of the magnetic resonance than the excitation from the hyperfine level with F = 4. This result has been theoretically explained under the assumption that the spin state of the alkali atomic nucleus does not change at collision with a nitrogen molecule, which is accompanied by a nonradiative transition of the alkali atom from the excited 2P1/2 state to the ground 2S1/2 state.
关键词： optical orientation,nonradiative transition,magnetic resonance,hyperfine structure,buffer gas,spin polarization,alkali atoms
更新于2025-09-19 17:15:36
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Investigations of the possible second-stage laser cooling transitions for the holmium atom magneto-optical trap
摘要： In this work laser-spectroscopic investigations of selected electronic levels in the holmium atom are performed in the context of possible second-stage laser cooling transitions which can be considered in a magneto-optical trap. Five transitions were directly recorded by the method of laser induced fluorescence in a hollow cathode discharge. The hyperfine structure constants A and B for the upper even-parity J = 17 / 2 levels, evaluated in earlier works, were generally confirmed, and their accuracy was improved; thus the frequency differences between the hyperfine structure components, relevant for the possibility of application of the hyperfine repumping, could be determined. Investigations of the Zeeman-hyperfine structure of these spectral lines were performed in order to evaluate the Landé g J factors of the upper levels; these were reported for the first time. Semi-empirical preliminary calculations of the lifetimes of the even-parity levels in question were also carried out, allowing estimation of the expected Doppler limits for the possible narrow-band laser cooling at the respective transitions. The degree of similarity between the g J factors of the upper levels of the cooling transitions and the ground state is important for the efficiency of the sub-Doppler laser cooling in a magneto-optical trap. The results presented might facilitate the choice of the most favorable option of obtaining narrow-band laser cooling of the holmium atoms.
关键词： Landé factors,Hyperfine structure,Laser cooling,Laser spectroscopy,Holmium,Electronic levels’ lifetimes
更新于2025-09-19 17:13:59
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Coupled large amplitude motions: The effects of two methyl internal rotations and 14N quadrupole coupling in 4,5-dimethylthiazole investigated by microwave spectroscopy
摘要： The molecular jet Fourier-transform microwave spectrum of 4,5-dimethylthiazole has been recorded between 2.0 and 26.5 GHz, revealing torsional splittings arising from two inequivalent methyl internal rotations with relatively low hindering barriers and nitrogen quadrupole hyperfine structures. Two global fits with 1009 hyperfine components of 315 rotational transitions involving five torsional species were performed using the program XIAM and BELGI-Cs-2Tops-hyperfine, an extended version of the BELGI-Cs-2Tops code which includes the effect of the 14N quadrupole coupling, giving a root-mean-square deviation of 399.8 kHz and 4.2 kHz, respectively. Compared to the monomethyl substituted thiazole derivatives, the barriers to internal rotation are drastically lower. This is also in contrast to chemical intuition which suggests high barriers due to steric hindrance. Because of the strong interaction between the methyl groups, strong top-top couplings in both the potential energy and kinetic parts of the Hamiltonian were observed.
关键词： dimethylthiazole,rotational spectroscopy,large amplitude motions,internal rotation,quadrupole hyperfine structure
更新于2025-09-19 17:13:59
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Mid-infrared laser absorption spectroscopy of the Ne–NO(X <sup>2</sup> Π) complex
摘要： The rovibrational spectrum of the Ne–NO(X2Π) open-shell complex has been measured in the 5.3 μm region using distributed feed-back quantum cascade lasers to probe the direct absorption in a slit-jet supersonic expansion. Three P-subbands (P′ ← P′′: 1/2 ← 1/2, 3/2 ← 1/2, and 5/2 ← 3/2) were observed, where P is the projection of the angular momentum J along the inertial a-axis of the complex. The hyperfine structure due to the nuclei spin of 14N (I = 1) was partially resolved in the P′ ← P′′: 1/2 ← 1/2 and 3/2 ← 1/2 subbands. The observed mid-infrared spectrum of Ne–NO (X2Π) together with the previously reported microwave spectrum was analyzed using a modified semirigid asymmetric rotor Hamiltonian for a planar open-shell complex. The band origin is located at 1876.0606(97) cm?1, which is blue-shifted from that of the NO monomer by only 0.0888 cm?1. The complex shows strong structural relaxation upon excitation of the overall rotation and the internal rotation of the NO subunit.
关键词： mid-infrared,hyperfine structure,rovibrational spectrum,Ne–NO,quantum cascade lasers
更新于2025-09-12 10:27:22