- 标题
- 摘要
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- 实验方案
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Single titanium-oxide species implanted in 2D g-C3N4 matrix as a highly efficient visible-light CO2 reduction photocatalyst
摘要： A visible-light-response, efficient and robust photo-catalyst for CO2 reduction is highly desirable. Herein, we demonstrate that single titanium-oxide species implanted in two-dimensional (2D) graphitic carbon nitride (g-C3N4) matrix (2D TiO-CN) can efficiently photo-catalyze the reduction of CO2 to CO under the irradiation of visible light. The synergistic interaction between single titanium oxide species and g-C3N4 in 2D TiO-CN not only enhances the separation of photo-excited charges, but also results in visible light response of single titanium-oxide species, realizing high activity of CO2 photo-reduction with extremely high CO generation rate of 283.9 μmol·h?1·g?1, 5.7, 6.8 and 292.2 times larger than those of TiO2/CN hybrid material, CN and commercial TiO2, respectively. Time-resolved fluorescence and electron spin resonance spectroscopy revealed the catalytic mechanism of the fabricated 2D TiO-CN photocatalysts for CO2 reduction.
关键词： two-dimensional (2D) photocatalysts,graphitic carbon nitride,visible-light,single atom catalyst,CO2 reduction
更新于2025-09-11 14:15:04
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Photoinduced reversible isomerization of 9H-fluorene into 1H-fluorene by means of hydrogen-atom migration and the lowest electronically excited triplet state studied by matrix-isolation FTIR spectroscopy
摘要： Photoinduced reversible intramolecular hydrogen-atom migration between 9H-?uorene and 1H-?uorene isolated in an Ar matrix is found by FTIR spectroscopy with an aid of DFT calculation. The forward isomerization from 9H-?uorene to 1H-?uorene occurs upon UV irradiation (λ ≥ 295 nm), while the backward isomerization occurs upon λ ≥ 320 nm light irradiation. The less stable isomer, 1H-?uorene, is identi?ed by comparison of the measured IR spectrum with the corresponding simulated spectral pattern obtained at the B3LYP/6-31++G(d,p) level. In addition, an IR spectrum of 9H-?uorene in the T1 state is measured during UV irradiation (λ ≥ 275 nm).
关键词： Electronically excited T1 state,Fluorene,Matrix-isolation infrared spectrum,Photoinduced hydrogen-atom migration
更新于2025-09-11 14:15:04
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Phase response of atom interferometers based on sequential Bragg diffractions
摘要： Large Momentum Transfer (LMT) beam splitters are implemented in atom interferometers to increase their sensitivity. However, LMT-interferometer light-pulses that modify the response function of the atom requires additional interferometer. In this paper, we develop an analytical model for the sensitivity function of the LMT-interferometers using sequential accelerating light pulses. We use the sensitivity function to calculate the acceleration sensitivity taking into account the pulse duration. In addition, the sensitivity to laser phase fluctuations is calculated, and we show that the pulse sequence can be engineered to mitigate the phase noise sensitivity.
关键词： large momentum beam splitter,atom interferometry,sensitivity function
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Ultracold Atom Gravimeter
摘要： Atom interferometry allows for the realisation of inertial sensors based on laser cooled atoms. Their limits in performances, both in terms of accuracy and stability, are linked to the temperature of the atomic cloud, in the low μK range, and more speci?cally, to the residual ballistic expansion of the atomic sources in the laser beams. To overcome these limits, we use as a source ultracold atoms in the nano-kelvin range in our absolute atom gravimeter.
关键词： Absolute sensor,Gravimetry,Ultracold atoms,Atom interferometry
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Rabi Resonance Measurements Based on CS Vapor Cell for Microwave Magnetic Field Detection in Free Space
摘要： In this paper we characterized the lineshapes of Rabi resonances for microwave (MW) magnetic field with cesium vapor cell in free space. The relation between resonance lineshapes and phase modulation frequency under different experimental parameters are investigated. Based on the obtained lineshapes, the evaluation of Rabi frequency has been done in free space. Optimal laser intensity and cell temperature are obtained in our experiment, preliminary analysis of the experimental results is reported.
关键词： Atom-based microwave measurements,lineshapes,atomic vapor cell,free space,magnetic field,Rabi resonance
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Feasibility Study for Atomic Measurement of Microwave Strength at Arbitrary Frequencies Within the Full X-Band
摘要： In this paper, the double-resonance spectra of cesium atoms in a glass cell inserted in a WR-90 waveguide were obtained in DC magnetic fields with field strengths of tens of milliTesla. This result confirmed that the resonant lines at both ends of the double-resonance spectrum shifted to 8.24 GHz and 10.18 GHz, respectively, due to the Zeeman effect with the DC magnetic flux density of 40 mT. This result is useful as a feasibility study for the atomic measurement of a microwave strength at arbitrary frequencies within the full X-band.
关键词： Microwave bands,Atom optics,Cesium,Spectroscopy,Microwave measurement,Atomic measurements
更新于2025-09-10 09:29:36
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Highly Stable and Multifunctional Aza-BODIPY-Based Phototherapeutic Agent for Anticancer Treatment
摘要： Phototherapy, as an important class of noninvasive tumor treatment methods, has attracted extensive research interest. Although a large amount of the near-infrared (NIR) phototherapeutic agents have been reported, the low efficiency, complicated structures, tedious synthetic procedures, and poor photostability limit their practical applications. To solve these problems, herein, a donor?acceptor?donor (D?A?D) type organic phototherapeutic agent (B-3) based on NIR aza-boron-dipyrromethene (aza-BODIPY) dye has been constructed, which shows the enhanced photothermal conversion efficiency and high singlet oxygen generation ability by simultaneously utilizing intramolecular photoinduced electron transfer (IPET) mechanism and heavy atom effects. After facile encapsulation of B-3 by amphiphilic DSPE?mPEG5000 and F108, the formed nanoparticles (B-3 NPs) exhibit the excellent photothermal stabilities and reactive oxygen and nitrogen species (RONS) resistance compared with indocyanine green (ICG) proved for theranostic application. Noteworthily, the B-3 NPs can remain outstanding photothermal conversion efficiency (η = 43.0%) as well as continuous singlet oxygen generation ability upon irradiation under a single-wavelength light. Importantly, B-3 NPs can effectively eliminate the tumors with no recurrence via synergistic photothermal/photodynamic therapy under mild condition. The exploration elaborates the photothermal conversion mechanism of small organic compounds and provides a guidance to develop excellent multifunctional NIR phototherapeutic agents for the promising clinical applications.
关键词： heavy atom effects,intramolecular photoinduced electron transfer,donor?acceptor?donor type,NIR phototherapeutic agents,aza-BODIPY
更新于2025-09-10 09:29:36
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Space qualified microwave source for cold atom clock operating in orbit
摘要： The space cold atom clock (CAC) suffers more degradation of frequency stability from the local oscillator noise compared with fountain clocks operating on the ground because of the larger dead time of the clock cycle. Therefore, low phase noise is required for the microwave source of the space CAC in addition to robustness, compactness, and adaptability to the space environment. This paper presents the design and measurements of a low-phase-noise space quali?ed microwave source for the cold atom clock experiment in space CAC operating in the Tiangong-2 Chinese space laboratory. At frequencies near the carrier, a phase noise level of 10?6.7 × f ?1.5 rad2/Hz ( f is the Fourier frequency) is achieved. This guarantees a frequency stability of 1.4 × 10?13 τ?1/2 (τ is the average time in seconds) for the typical space CAC operation cycle.
关键词： cold atom clock,space quali?ed,frequency stability,microwave source,phase noise
更新于2025-09-10 09:29:36
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Enhancing nanomechanical squeezing by atomic interactions in a hybrid atom-optomechanical system
摘要： In a hybrid atom-optomechanical system, the optical coupling of a mechanical mode of a nanomembrane in an optical cavity with a distant interacting atom gas permits highly nonclassical quantum many-body states. We show that the mechanical mode can be squeezed by the backaction of internal excitations of the atoms in the gas. A Bogoliubov approach reveals that these internal excitations form a fluctuating environment of quasiparticle excitations for the mechanical mode with a gaped spectral density. Nanomechanical squeezing arises due to quasiparticle excitations in the interacting atom gas when the mechanical frequency is close to resonance with the internal atomic transitions. Interestingly, nanomechanical squeezing is enhanced by atom-atom interactions.
关键词： Bogoliubov approach,atom-optomechanical system,quasiparticle excitations,nanomechanical squeezing,atom-atom interactions
更新于2025-09-09 09:28:46
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Nonlinear coherent perfect photon absorber in asymmetrical atom–nanowires coupling system
摘要： Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perfect absorber (CPA) beyond the linear regime. As nanowire-based system is a more competitive candidate for full-optical device, we introduce a nonlinear CPA in the single two-level atom–nanowires coupling system in this work. Nonlinear input–output relations are derived analytically, and three contributions of atomic saturation nonlinearity are explicit. The consociation of optical nonlinearity and destructive interference makes it feasible to fabricate a nonlinear monoatomic CPA. Our results also indicate that a nonlinear system may work linearly even when the incoming lights are not weak any more. Our findings show promising applications in full-optical devices.
关键词： single-atom system,nonlinear coherent perfect absorber,atom–nanowires coupling
更新于2025-09-09 09:28:46