Transition In Cesium Research Articles

Coherent amplitude modulation of continuous-wave light in cesium vapor.

We report on observations of coherent, sustained oscillations in the absorption of continuous-wave light at 388 nm that excites the 6S1/2 → 8P3/2 transition in cesium (Cs) vapor. The oscillation frequency is close to the spacing of hyperfine levels of the 8P3/2 level that are excited simultaneously by the 388 nm field. We observe a threshold behavior of the oscillation amplitude with pump power and suggest that the effect is associated with infrared directional emission due to amplified spontaneous emission (ASE) from the 8P3/2 → 8S1/2 transition that is assisted by retro-reflections from cell windows. The effect may be used to probe a lasing process in an atomic vapor, by checking the temporal properties of the pump field transmitted through the vapor.

Theoretical and experimental study of the 6S-8S two-photon absorption cross-section in cesium atoms.

The probability of a two-photon absorption (TPA) process is quantified by means of the TPA cross-section. In this work the TPA cross-section for the 6S1/2 → 8S1/2 transition in cesium (Cs) atoms is obtained from a theoretical and experimental approach. It is calculated using second order perturbation theory including hyperfine structure and Doppler broadening for a thermal atomic vapor. The theoretical values for the TPA cross-sections of the two allowed hyperfine transitions are σ~3,3=3.10×10-24 cm4/W and σ~4,4=3.65×10-24 cm4/W. An experiment is set up to measure these cross-sections based on the quadratic dependence between the TPA transition rate and the intensity of the laser light. Values of σ~3,3=(3.6±1.1)×10-24 cm4/W and σ~4,4=(4.6±1.1)×10-24 cm4/W are obtained from the measurements. The results show an agreement between theory and experiment. To the best of our knowledge, this is the first time that these cross-sections are reported.

Перспективы использования метода фиторемедиации для дезактивации загрязненных радионуклидами территорий

Soil contamination with radionuclides, the main cause of which is the accident at the Chernobyl nuclear power plant, is one of the most dangerous negative environment impact factors. Phytoremediation including cultivation of «energy» crops is an effective method for decontamination of territories contaminated with radionuclides. The advantage of this approach is the possibility of using biomass as a renewable source of green energy in combination with the gradual reclamation of polluted soils. A promising crop for the purposes of phytoremediation is willow, the fast-growing species of which provide a high yield of biomass from a production plantation. A problematic issue is the safe use of willow biomass. The assessment of the conditions for the transition of radioactive cesium into willow biomass was carried out on the territories of Belarus contaminated after the Chernobyl accident. Experiments have shown that the predicted content of 137Cs in the wood of a fast-growing willow is significantly lower than the level allowed for wood fuel according to the standards established for the Republic of Belarus (740 Bq/kg). Even at the level of soil pollution at which they are removed from agricultural use (40 Ci/km2), the content of 137Cs in wood will be from 35 to 120 Bq/kg (depending on the dose of potash fertilizers).

Antiresonant Fabry-Pérot cavity with ultralow finesse

The exact expressions of finesse and full width at half maximum (FWHM) of the Airy distribution of a Fabry-P\'erot (FP) resonator are derived, which solves the breakdown problem at ultralow reflectivity in traditional formulas. We demonstrate that, when the cavity-mirror reflectivity $R\ensuremath{\rightarrow}0$, the FWHM approaches half of the free spectral range rather than infinity; moreover, the cavity finesse $\mathcal{F}$ approaches 2 rather than zero. These expressions are useful for the development of bad-cavity lasers, such as the four-level active optical clock based on the strong atomic transition of cesium. Also, the exact expressions of the FWHM and finesse of the reflection distribution composed of reflected mode profiles are derived, which separately intersect with that of the Airy one at $R=0$. In addition, the characteristics of an antiresonant cavity, the frequency of which is exactly at the center of two adjacent resonant cavity modes, are analyzed. It is demonstrated that at the resonant and antiresonant frequencies the enhancement and inhibition of intracavity light intensity caused by the FP cavity are symmetrical in the logarithmic view. Furthermore, we provide a universal expression of the cavity-enhancement factor rather than the classical representation of ``$\text{2}\mathcal{F}/\phantom{\text{2}\mathcal{F}\ensuremath{\pi}}\phantom{\rule{0.0pt}{0ex}}\ensuremath{\pi}$,'' which is inadequate for the high-loss cavity because the cavity-enhancement factor should naturally reach 1 when $R\ensuremath{\rightarrow}0$. Finally, we extend the application of the antiresonant cavity to an inhibited laser, the frequency of which has a stronger suppression effect on the cavity-length thermal noise than the traditional resonant laser.

Analysis of an Optical Lattice Methodology for Detection of Atomic Parity Nonconservation

We present an extension and a deepened analysis of a suggested experimental scheme for detecting atomic parity violation, previously published in Phys. Rev. A 2019, 100, 050101. The experimental concept is described in more detail and we compute new ab initio data necessary for assessing the plausibility of the approach. Original theoretical data for transition matrix elements on the electric dipole forbidden transition in caesium 6 s 2 S 1 / 2 – 5 d 2 D 3 / 2 are reported, as are a range of electric dipole matrix elements connected to the ground state 6s. The latter is used for an analysis of the wavelength-dependent light shift in Cs. A range of experimental details is presented, combined with a survey of realistic lasers parameters. These are adopted to project the feasibility of the scheme to eventually be capable of delivering data beyond the standard model of particle physics.

Correction: Synthesis and model simulation of the hexagonal to circular transition of perovskite cesium lead halide nanosheets by rapidly changing the temperature

Correction for ‘Synthesis and model simulation of the hexagonal to circular transition of perovskite cesium lead halide nanosheets by rapidly changing the temperature’ by Zhong-Hai Lin et al., RSC Adv., 2020, 10, 4211–4217, DOI: 10.1039/C9RA10312K.

Synthesis and model simulation of the hexagonal to circular transition of perovskite cesium lead halide nanosheets by rapidly changing the temperature.

Lead halide perovskites have emerged as promising optoelectronic materials due to their excellent efficiencies in photovoltaic and light-emitting applications. CsPbBr3 is a kind of all-inorganic perovskite that exhibits higher stability. Here, we report the synthesis of hexagonal and circular all-inorganic CsPbBr3 perovskite nanoplates by changing the reaction temperature. As time goes on, the different reaction temperatures play an important role in determining the shape and size. We use first-principles to explicate the formation of hexagonal nanoplates. Meanwhile, a model is built and the calculation of the properties is conducted. In brief, a method to directly and conveniently synthesize all-inorganic CsPbBr3 is proposed.

Continuously tunable single-frequency 455 nm blue laser for high-state excitation transition of cesium.

A continuously tunable high-power single-frequency 455nm blue laser for high-state excitation transition 6S1/22↔7P3/22 of Cs atoms was presented in this Letter, which was implemented by an intracavity frequency-doubled Ti:sapphire laser with an LBO crystal. The highest output power of 1.0W was attained under a pump power of 13.5W with an optical conversion efficiency of 7.4%. The measured power stability in 3h and beam quality were better than ±0.27% (peak-to-peak) and Mx2=1.58, My2=1.18, respectively. By continuously scanning the length of the resonator after locking the employed intracavity etalon to the oscillating longitudinal mode of the laser, the continuous tuning range of the 455nm blue laser was up to 32GHz and was mode hop free. Lastly, the whole saturation absorption spectrum of the higher state excitation transition 6S1/22(Fg=3)↔P3/22(Fe=2,3,4) and 6S1/22(Fg=4)↔7P3/22(Fe=3,4,5) of Cs133 was successfully observed in the experiment, which further verified the excellent performance of the 455nm blue laser.

Laser-cooled cesium atoms confined with a magic-wavelength dipole trap inside a hollow-core photonic-bandgap fiber

We report loading of laser-cooled caesium atoms into a hollow-core photonic-bandgap fiber and confining the atoms in the fiber's 7 $\mu m$ diameter core with a magic-wavelength dipole trap at $\sim$935 nm. The use of the magic wavelength removes the AC-Stark shift of the 852nm optical transition in caesium caused by the dipole trap in the fiber core and suppresses the inhomogeneous broadening of the atomic ensemble that arises from the radial distribution of the atoms. This opens the possibility to continuously probe the atoms over time scales of a millisecond -- approximately 1000 times longer than what was reported in previous works, as dipole trap does not have to be modulated. We describe our atom loading setup and its unique features and present spectroscopy measurements of the caesium's D$_{2}$ line in the continuous wave dipole trap with up to $1.7 \times 10^{4}$ loaded inside the hollow-core fiber.

Small- to large-scale comparisons of cesium ion exchange performance with spherical resorcinol formaldehyde resin

ABSTRACTIon exchange performance using spherical resorcinol formaldehyde resin was compared at three process scales (10 mL, 34 gal, and 297 gal). The small-scale test demonstrated earlier cesium breakthrough, but higher cesium capacity, relative to the large-scale tests. The low superficial flow velocity at the small scale impacted the cesium load profile resulting in a longer transition zone. Based on these results, small-scale column test results with actual tank waste will likely be worst case bounding with respect to initial cesium breakthrough and transition zone length, but could overpredict cesium capacity when extrapolated to large-scale column operations.

Influence of pump light on sensitivity of magnetometer based on linearly polarized Bell-Bloom structure

Magnetometry has already been widely used in mineral exploration, medical exploration and precision measurement physics. One is trying to improve the sensitivity of the magnetometer. One of the most widely used magnetometers is based on the Bell-Bloom structure, which can be realized by modulating the pump light. The sensitivity of the Bell-Bloom magnetometer is determined by the magnetic resonance linewidth (MRL) and the signal-to-noise under the condition of magnetic resonance (SNR). Both are affected by the pump intensity and the relaxation rate of the atoms. In order to achieve a higher sensitivity, how these factors affect the magnetic field measurement should be analyzed. In this paper, the influence of the pump light on the sensitivity of the linearly polarized Bell-Bloom magnetometer is investigated based on the Bloch equation with amplitude modulated pump beam and the rate equations with spin relaxation. The rate equations are obtained from the Liouville equation, and the theoretical analysis is based on the cesium. The pump beam is linearly polarized and is resonant to D<sub>1</sub> transition of cesium. Both the direct pump (pump frequency is resonant to <inline-formula><tex-math id="M500">\begin{document}${6^2}{{\rm{S}}_{1/2}}\;F = 4$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_M500.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_M500.png"/></alternatives></inline-formula>−<inline-formula><tex-math id="Z-20190422020150-2">\begin{document}${6^2}{{\rm{P}}_{1/2}}\;F' = 3$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_Z-20190422020150-2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_Z-20190422020150-2.png"/></alternatives></inline-formula> transition) and the indirect pump (pump frequency is resonant to <inline-formula><tex-math id="M501">\begin{document}${6^2}{{\rm{S}}_{1/2}}\;F = 3 $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_M501.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_M501.png"/></alternatives></inline-formula>−<inline-formula><tex-math id="Z-20190422020310-3">\begin{document}${6^2}{{\rm{P}}_{1/2}}\;F' = 4$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_Z-20190422020310-3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_Z-20190422020310-3.png"/></alternatives></inline-formula> transition) are analyzed. The experiment is performed based on a 20-mm cube cesium vapour cell with 20-Torr helium as buffer gas. The linearly polarized probe beam is tuned to resonance to cesium D<sub>2</sub> transition <inline-formula><tex-math id="M502">\begin{document}${6^2}{{\rm{S}}_{1/2}}\;F = 4$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_M502.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_M502.png"/></alternatives></inline-formula>−<inline-formula><tex-math id="Z-20190422020405-4">\begin{document}$ {6^2}{{\rm{P}}_{3/2}}\;F' = 5$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_Z-20190422020405-4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_Z-20190422020405-4.png"/></alternatives></inline-formula>, and the intensity of the probe is 0.2 W/m<sup>2</sup>. The spectra of magnetic resonance are measured by using the lock-in detection with a scanning of the modulation frequency. Then the sensitivity can be obtained by measuring MRL and SNR. The experimental results show that the sensitivity and the pump intensity are related nonlinearly, which is coincident with theoretical result. Higher sensitivity can be obtained under the condition of indirect pump. In addition, the effect of atomic spin relaxation on sensitivity is also analyzed with the indirect pump beam. This work clarifies the dynamics of the Bell-Bloom magnetometer to some extent. The highest sensitivity obtained is <inline-formula><tex-math id="M503">\begin{document}$31.7\;{\rm{pT}}/\sqrt {{\rm{Hz}}} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_M503.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20190030_M503.png"/></alternatives></inline-formula> in our experiment, which can be optimized by using other kinds of vapour cells and different measuring methods.

Low-drift Zeeman shifted atomic frequency reference

We present a simple method for producing a low-drift atomic frequency reference based upon the Zeeman effect. Our Zeeman Shifted Atomic Reference `ZSAR' is demonstrated to have tens of GHz tuning range, limited only by the strength of the applied field. ZSAR uses Doppler-free laser spectroscopy in a thermal vapor where the vapor is situated in a large, static and controllable magnetic field. We use a heated $^{85}$Rb vapor cell between a pair of position-adjustable permanent magnets capable of applying magnetic fields up to 1 T. To demonstrate the frequency reference we use a spectral feature from the Zeeman shifted D1 line in $^{85}$Rb at 795 nm to stabilize a laser to the 7S$_{1/2}$ $\longrightarrow$ 23P$_{1/2}$ transition in atomic cesium, which is detuned by approximately 19 GHz from the unperturbed Rb transition. We place an upper bound on the stability of the technique by measuring a 2.5 MHz RMS frequency difference between the two spectral features over a 24 hour period. This versatile method could be adapted easily for use with other atomic species and the tuning range readily increased by applying larger magnetic fields.

Possible phase transition in liquid caesium at ambient pressure

ABSTRACTWe report a molecular dynamics study of liquid caesium at ambient pressure intended to check the possibility of liquid‒liquid phase transformation at K. We find the presence of small kinks on thermodynamic characteristics of the system, but no phase transition.

Comparing laser induced plasmas formed in diode and excimer pumped alkali lasers.

Lasing on the D1 transition (62P1/2 → 62S1/2) of cesium can be reached in both diode and excimer pumped alkali lasers. The first uses D2 transition (62S1/2 → 62P3/2) for pumping, whereas the second is pumped by photoexcitation of ground state Cs-Ar collisional pairs and subsequent dissociation of diatomic, electronically-excited CsAr molecules (excimers). Despite lasing on the same D1 transition, differences in pumping schemes enables chemical pathways and characteristic timescales unique for each system. We investigate unavoidable plasma formation during operation of both systems side by side in Ar/C2H6/Cs.

Fluorescence filters based on alkali-metal atomic vapors

We study the characteristics of narrow-band atomic fluorescence filters intended for isolation of usable signals from broadband background radiation. These filters use alkali-metal atomic vapors as the filter medium, and we compare the parameters of various filters. Filters using allowed transitions in rubidium and cesium were found to offer the best designs.

137Cs accumulation in the yield of agricultural crops depending on the impact of agrochemical factors

We summarized the results of long-term research of fertili zing system and chemical melioration on radio cesium transition info yield of agricultural crops. The effect of such heavy fertilizer elements as magnesium and sulfur, participating in the nitrogen, phosphoric and carbohydrate metabolism in plants, on the crop formation and quality is studied. The influence of liming, level of providing soil with phosphorus and potassium, doses of nitrogen fertilizers in top-dressing, on buildup of radionuclide in crop yields is shown. The influence of the complex nitrogen-free fertilizer «Ekoplant» and its inclusion doses on the straw flax crop is defined. It has been shown the possibility of using the angustifolins lupine on sod-podzolic sandy soils with 10 Ci/km2 radio cesium contamination. It has been shown the dependence of radionuclide accumulation on perennial grasses hay harvest that were grown on sod-podzolic sandy soils of Polissia with 10 Ci/km2 radio cesium contamination.

Investigation of the phase transitions in cesium by the average atom model

Investigation of the phase transitions in cesium by the average atom model

Self-heterodyne interference spectroscopy using a comb generated by pseudo-random modulation.

We present an original instrument designed to accomplish high-speed spectroscopy of individual optical lines based on a frequency comb generated by pseudo-random phase modulation of a continuous-wave (CW) laser. This approach delivers efficient usage of the laser power as well as independent control over the spectral point spacing, bandwidth and central wavelength of the comb. The comb is mixed with a local oscillator generated from the same CW laser frequency-shifted by an acousto-optic modulator, enabling a self-heterodyne detection scheme. The current configuration offers a calibrated spectrum every 1.12 µs. We demonstrate the capabilities of the spectrometer by producing averaged, as well as time-resolved, spectra of the D1 transition of cesium with a 9.8-MHz point spacing, a 50-kHz resolution and a span of more than 3 GHz. The spectra obtained after 1 ms of averaging are fitted with complex Voigt profiles that return parameters in good agreement with expected values.

Superradiance for Atoms Trapped along a Photonic Crystal Waveguide.

We report observations of superradiance for atoms trapped in the near field of a photonic crystal waveguide (PCW). By fabricating the PCW with a band edge near the D(1) transition of atomic cesium, strong interaction is achieved between trapped atoms and guided-mode photons. Following short-pulse excitation, we record the decay of guided-mode emission and find a superradiant emission rate scaling as Γ̅(SR)∝N̅Γ(1D) for average atom number 0.19≲N̅≲2.6 atoms, where Γ(1D)/Γ'=1.0±0.1 is the peak single-atom radiative decay rate into the PCW guided mode, and Γ' is the radiative decay rate into all the other channels. These advances provide new tools for investigations of photon-mediated atom-atom interactions in the many-body regime.

根部エンドファイトPhialocephala fortinii BPC3によるトマトへのCs-137移行の抑制

根部エンドファイトPhialocephala fortinii BPC3によるトマトへのCs-137移行の抑制