- 标题
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- 实验方案
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Time-Resolved Impulsive Stimulated Raman Spectroscopy with Synchronized Triple Mode-Locked Lasers
摘要： A complete understanding of a photochemical reaction dynamics begins with real-time measurements of both electronic and vibrational structures of photoexcited molecules. Time-resolved impulsive stimulated Raman spectroscopy (TR-ISRS) with femtosecond actinic pump, Raman pump, and Raman probe pulses is one of the incisive techniques enabling one to investigate the structural changes of photoexcited molecules. Here, we demonstrate that such femtosecond TR-ISRS is feasible with synchronized triple mode-locked lasers without using any time-delay devices. Taking advantage of precise control of the three repetition rates independently, we could achieve automatic scanning of two delay times between the three pulses, which makes both rapid data acquisition and wide dynamic range measurement of the fifth-order TR-ISRS signal achievable. We thus anticipate that the present triple mode-locked laser-based TR-ISRS technique will be of critical use for long-term monitoring of photochemical reaction dynamics in condensed phases and biological systems.
关键词： pump-dump-probe,fifth-order electronic spectroscopy,impulsive stimulated Raman spectroscopy,femtosecond Raman scattering,Time-resolved vibrational spectroscopy
更新于2025-09-23 15:21:01
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Comparison of quantitative analyses using SIMS, atom probe tomography, and femtosecond laser ablation inductively coupled plasma mass spectrometry with Si <sub/>1a??X</sub> Ge <sub/>X</sub> and Fe <sub/>1a??X</sub> Ni <sub/>X</sub> binary alloys
摘要： Due to their electrical and physical properties, Si1?XGeX materials are widely used in microelectronic devices. In particular, the Ge component found within Si1?XGeX compounds is important for enhancing carrier mobility and altering the lattice constant of metal-oxide-semiconductor field-effect transistors. In this study, magnetic sector secondary ion mass spectrometry (magnetic sector SIMS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to determine the accurate concentrations of major compositions present within binary alloy samples. However, quantitative SIMS analysis is limited by the matrix effect, which influences the sputter yield of an element in a compound and alters the secondary ionization yields. Quantitative deviations that were due to the matrix effect were reduced by using Cs cluster ions (MCs+ and MCs2+) instead of elemental ions; the SIMS results using the elements were, therefore, compared with those using MCs+ and MCs2+ cluster ions. In the case of Fe1?XNiX alloys that have a less matrix effect compared to Si1?XGeX alloys, both the Cs primary ion beam (Cs+) and an oxygen primary ion beam (O2+) were used to measure the Fe1?XNiX compositions. The quantitative results from the two different primary ion beams were then compared to understand the ionization process. Deviations in the quantitative values gained with the O2+ beam were lower than those obtained using the Cs+ primary ions, meaning that using oxygen as the primary ion improves the accuracy in quantifying Fe1?XNiX compounds. Other reliable tools for analysis such as atom probe tomography and femtosecond laser ablation inductively coupled plasma mass spectrometry were also used in the quantitative analysis, with results that were consistent with the most accurate results obtained using magnetic sector SIMS and ToF-SIMS.
关键词： Si1?XGeX,femtosecond laser ablation inductively coupled plasma mass spectrometry,atom probe tomography,SIMS,Fe1?XNiX,binary alloys
更新于2025-09-23 15:21:01
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Single-photon limit of dispersive readout of a qubit with a photodetector
摘要： We study the dispersive readout of a qubit in the ultimate limit of a single-photon probe. The use of a single-photon probe avoids the errors due to nonorthogonality of coherent states. A photodetector is used in the scheme we consider. The dynamics of the system is studied using the Heisenberg-Langevin equations. We treat the counter-rotating terms in the Hamiltonian perturbatively, which leads to the Bloch-Siegert shift in the resonator frequency. It is shown how the shift can improve the readout. The theory of photon transport through the qubit and the resonator it couples to is provided while taking the effect of the counter-rotating terms into account. To calculate the readout contrast, we use two approaches. The first one neglects the qubit relaxation and allows us to derive a compact expression for the contrast. Also, we obtain simple estimates for the system parameters to maximize the contrast. The second approach accounts for the qubit relaxation, which allows us to further improve the contrast. We demonstrate that for a readout time of 1 μs, a contrast of more than 75% can be achieved for an ideal detector and single-photon source.
关键词： Heisenberg-Langevin equations,qubit,dispersive readout,photon transport,Bloch-Siegert shift,readout contrast,photodetector,single-photon probe
更新于2025-09-23 15:21:01
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Highly Conjugated, Fused-Ring, Quadrupolar Organic Chromophores with Large Two-Photon Absorption Cross-Sections in the Near-Infrared
摘要： The two-photon absorption (2PA) properties are investigated for two series of organic, π-conjugated, fused-ring, quadrupolar A-π-D-π-A chromophores of the type originally developed as non-fullerene acceptors for organic photovoltaics. These molecules are found to exhibit large nondegenerate two-photon absorption (ND2PA) cross-sections (ca. 6-27 × 103 GM) in the near infrared (NIR). In the first series, involving molecules of varying core size, ND2PA spectra and cross-sections characterized by femtosecond ND2PA spectroscopy in chloroform solutions reveal that increases in core size, and thus conjugation length, leads to substantially red-shifted and enhanced 2PA. In a second series, variation of the strength of the terminal acceptor (A) with constant core size (7 rings, indacene-based) led to less dramatic variation in the 2PA properties. Among the two core types studied, compounds in which the donor has a thieno[3,2-b]thiophene center demonstrate larger 2PA cross-sections than their indacene-centered counterparts, due to the greater electron-richness of their cores amplifying intramolecular charge transfer. Excited-state absorption (ESA) contributions to nonlinear absorption measured by open-aperture Z-scans are deduced for some of the compounds by analyzing the spectral overlap between 2PA bands and NIR ESA transitions obtained by ND2PA and transient absorption measurements, respectively. ESA cross-sections extracted from transient absorption and irradiance-dependent open-aperture Z-scans are in reasonable agreement and their moderate magnitudes (ca. 10-21 m2) suggest that, although ESA contributions are non-negligible, the effective response is predominantly instantaneous 2PA.
关键词： pump-probe spectroscopy,Nonlinear optics,Z-scan,organic optoelectronics,ultrafast spectroscopy,two-photon absorption
更新于2025-09-23 15:21:01
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d-Glucose recognition based on phenylboronic acid-functionalized polyoligomeric silsesquioxane fluorescent probe
摘要： We report a new strategy to synthesize hybrid fluorescent nanosensors consisting of phenylboronic acid-functionalized POSS (POSS–PBA) and diol-modified 8-anilino-1-naphthalenesulfonic acid (ANSA (a fluorescent dye)) for the detection of the biologically important D-glucose. The probe was characterized by FT-IR and 1H-NMR analyses, and the photoluminescence intensity was measured under various conditions to confirm its glucose sensing ability. Our POSS-APBA-dye probe could detect glucose at concentrations of 0–20 mg/mL, with a good linear relationship even at low glucose concentrations of 0–1 mg/mL. The properties of the POSS-APBA-dye probe were evaluated and compared with those of an APBA-dye probe. The glucose sensing ability of our POSS-APBA-dye probe was largely unaffected by the presence of interfering substances. The probe showed high sensing ability in a pH 5 environment and long-term (approximately 40 days) fluorescence stability.
关键词： polyhedral oligomeric silsesquioxane,glucose sensor,fluorescence probe,boronic acid derivative
更新于2025-09-23 15:21:01
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A Colorimetric/Fluorescence Dual-channel Probe for Highly Discriminating Detection of Cysteine
摘要： In this work, a novel fluorescence (FL) probe for selective and sensitive detection of Cys with colorimetric and FL dual signal changes was reported. The probe was synthesized by two step of sulfonamide reaction coupling between a sulfonyl benzoxadiazole (SBD) dye and dansyl chloride linked with rigid piperazine group. The probe showed a specific off-on response to Cys in aqueous solution with nanomolar LOD, and without interference by a range of amino acids and several competing analytes. Upon addition of Cys, the probe will undergo sequential substitution and intramolecular rearrangement reactions, yielding a 4-amino SBD derivative, which results in generation of strong yellow fluorescence emission at 575 nm accompanied by a two-step red shift in the absorption spectral. Moreover, it can be used for imaging of endogenous Cys in living cells.
关键词： Fluorescence probe,Image analysis,Biothiols,Colorimetric
更新于2025-09-23 15:21:01
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Novel strategy for fabrication of sensing layer on thiol-functionalized fiber-optic tapers and their application as SERS probes
摘要： This work presents a new strategy to fabricate optical fiber surface-enhanced Raman scattering (SERS) probes with high-performance remote sensing prepared by thiol functionalization of silica fiber taper, and further in situ nucleation and growth of silver nanoparticles (AgNPs). The prepared fiber probes can effectively identify the analyte 4-aminothiophenol (4-ATP) with a limit of detection (LOD) as low as 2.15×10-11 M using a portable commercial Raman spectrometer. Simultaneously, such fiber probes have shown a good reproducibility with the relative standard deviation (RSD) value of 7.6%, and possessed high signal stability at room temperature over one month. Furthermore, this approach provides new insight into the fabrication of fiber SERS probe integrated the advantages in terms of sensitivity, reproducibility and stability, which shows great potential for practical SERS applications.
关键词： Thiol functionalization,SERS performance,Probe,Silver nanoparticles,Optical fiber
更新于2025-09-23 15:21:01
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Electric dipole of InN/InGaN quantum dots and holes and giant surface photovoltage directly measured by Kelvin probe force microscopy
摘要： We directly measure the electric dipole of inn quantum dots (QDs) grown on in-rich inGan layers by Kelvin probe force microscopy. This significantly advances the understanding of the superior catalytic performance of inn/inGan QDs in ion- and biosensing and in photoelectrochemical hydrogen generation by water splitting and the understanding of the important third-generation inGan semiconductor surface in general. the positive surface photovoltage (SpV) gives an outward QD dipole with dipole potential of the order of 150 mV, in agreement with previous calculations. After HCl-etching, to complement the determination of the electric dipole, a giant negative SpV of ?2.4 V, significantly larger than the inGan bandgap energy, is discovered. this giant SpV is assigned to a large inward electric dipole, associated with the appearance of holes, matching the original QD lateral size and density. Such surprising result points towards unique photovoltaic effects and photosensitivity.
关键词： electric dipole,Kelvin probe force microscopy,surface photovoltage,inn/inGan quantum dots,photovoltaic effects
更新于2025-09-23 15:21:01
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[IEEE 2019 4th International Conference on Power and Renewable Energy (ICPRE) - Chengdu, China (2019.9.21-2019.9.23)] 2019 4th International Conference on Power and Renewable Energy (ICPRE) - Laser Beam Path Control Using a PSD Fuzzy Controller
摘要： We present novel waveguide packaging for sub-millimeter and terahertz-wave devices, which is suitable for large chip-width MMICs and doesn’t require any additional fabrication process. With full electromagnetic simulation, we analyze possible wave modes in a rectangular waveguide with thin E-plane slits formed for inserting large-width MMICs into the split waveguide block and show that parasitic modes can be well suppressed by lossy and high-dielectric material. For a 1.1-mm-wide test IC in the 260–320 GHz band, measured transition loss is around 1 dB with more than 60 dB inter-port isolation.
关键词： terahertz wave,waveguide package,Integrated E-plane probe
更新于2025-09-23 15:21:01
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Dual-comb-based asynchronous pump-probe measurement with an ultrawide temporal dynamic range for characterization of photo-excited InAs quantum dots
摘要： A dual-comb-based asynchronous optical sampling (ASOPS) pump-probe measurement system is demonstrated for characterizing the relaxation dynamics in a photo-excited self-assembled InAs quantum dot (QD) semiconductor. Although the photo-excited QD material has multiple complex relaxation processes, the transient transmittance responses (from femtoseconds to nanoseconds) are successfully obtained within a sub-second short acquisition time by using the ASOPS system. This is achieved with high stability and an extremely wide temporal dynamic range of approximately 105. The utility of the developed system is demonstrated as a powerful and easy-to-use measurement tool for studying the complex photo-excited dynamics of QD materials.
关键词： dual-comb,asynchronous optical sampling,InAs quantum dots,pump-probe measurement,relaxation dynamics
更新于2025-09-23 15:21:01