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Highly Selective Optical Detection of Fe <sup>3+</sup> Ions in Aqueous Solution Using Label-Free Silicon Nanocrystals
摘要： Highly brightness amine-terminated silicon nanocrystals (Si NCs) have been utilized in a simple and rapid assay for the highly selective and sensitive detection of Fe3+ via quenching of their strong blue luminescence, without the need for analyte-specific labeling groups. Sensitive detection of Fe3+ is successfully demonstrated, with a linear relationship observed between luminescence quenching and Fe3+ concentration from 5 × 10?6 to 900 × 10?6 m and a limit of detection of 1.3 × 10?6 m. The Si NCs show excellent selectivity toward Fe3+ ions, with no quenching of the luminescence signal induced by the presence of Fe2+ ions, allowing for solution phase discrimination between the ionic species in different charge states.
关键词： nanocrystal,sensor,iron,optical detection
更新于2025-11-14 15:32:45
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Evaluating the influence of laser wavelength and detection stage geometry on optical detection efficiency in a single-particle mass spectrometer
摘要： Single-particle mass spectrometry (SPMS) is a useful tool for the online study of aerosols with the ability to measure size-resolved chemical composition with a temporal resolution relevant to atmospheric processes. In SPMS, optical particle detection is used for the effective temporal alignment of an ablation laser pulse with the presence of a particle in the ion source, and it gives the option of aerodynamic sizing by measuring the offset of particle arrival times between two detection stages. The efficiency of the optical detection stage has a strong influence on the overall instrument performance. A custom detection laser system consisting of a high-powered fibre-coupled Nd:YAG solid-state laser with a collimated beam was implemented in the detection stage of a laser ablation aerosol particle time-of-flight (LAAP-TOF) single-particle mass spectrometer without major modifications to instrument geometry. The use of a collimated laser beam permitted the construction of a numerical model that predicts the effects of detection laser wavelength, output power, beam focussing characteristics, light collection angle, particle size, and refractive index on the effective detection radius (R) of the detection laser beam. We compare the model predictions with an ambient data set acquired during the Ice in Clouds Experiment – Dust (ICE-D) project. The new laser system resulted in an order-of-magnitude improvement in instrument sensitivity to spherical particles in the size range 500–800 nm compared to a focussed 405 nm laser diode system. The model demonstrates that the limit of detection in terms of particle size is determined by the scattering cross section (Csca) as predicted by Mie theory. In addition, if light is collected over a narrow collection angle, oscillations in the magnitude of Csca with respect to particle diameter result in a variation in R, resulting in large particle-size-dependent variation in detection efficiency across the particle transmission range. This detection bias is imposed on the aerodynamic size distributions measured by the instrument and accounts for some of the detection bias towards sea salt particles in the ambient data set.
关键词： LAAP-TOF,aerosol,single-particle mass spectrometry,Mie theory,laser wavelength,detection stage geometry,optical detection efficiency
更新于2025-09-23 15:19:57
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[IEEE 2018 International Conference on Power System Technology (POWERCON) - Guangzhou, China (2018.11.6-2018.11.8)] 2018 International Conference on Power System Technology (POWERCON) - Partial Discharge Detection in Transformer Based on Optical Method
摘要： The paper presents a method for detecting partial discharge (PD) in transformer oil using fluorescence sensor and optical method. The main components and the experimental setup are described. The results show that the fluorescence sensor can effectively detect PD signals with high sensitivity and accuracy. The method has great potential for application in power equipment monitoring.
关键词： fluorescence sensor,power equipment,optical detection,transformer oil,partial discharge
更新于2025-09-19 17:15:36
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Flickering nanometre-scale disorder in a crystal lattice tracked by plasmonic flare light emission
摘要： The dynamic restructuring of metal nanoparticle surfaces is known to greatly influence their catalytic, electronic transport, and chemical binding functionalities. Here we show for the first time that non-equilibrium atomic-scale lattice defects can be detected in nanoparticles by purely optical means. These fluctuating states determine interface electronic transport for molecular electronics but because such rearrangements are low energy, measuring their rapid dynamics on single nanostructures by X-rays, electron beams, or tunnelling microscopies, is invasive and damaging. We utilise nano-optics at the sub-5nm scale to reveal rapid (on the millisecond timescale) evolution of defect morphologies on facets of gold nanoparticles on a mirror. Besides dynamic structural information, this highlights fundamental questions about defining bulk plasma frequencies for metals probed at the nanoscale.
关键词： nanoparticles,plasmonics,optical detection,gold,defects
更新于2025-09-19 17:13:59
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Polydimethylsiloxane (PDMS) Waveguide Sensor Detecting Fluid Flow Velocity by Mimicking the Fish Lateral Line Organ
摘要： Accurate measurement of fluid flow velocities is challenging but essential in many disciplines. Inspiration of possible measurement methods can come from nature, for example from the lateral line organ of fish, which is comprised of hair cells embedded in a gelatinous cupula. When the cupula is deflected by water movement, the hair cells initiate neural signals that generate an accurate image of the fish’s surroundings. We built a flow sensor mimicking a hair cell, yet coupled it with an optical detection method. Fluid flow bends the waveguide; this leads to a measurable light loss that depends linearly on the waveguide deflection.
关键词： optical detection principle,PDMS waveguide,biomimetic flow sensor
更新于2025-09-12 10:27:22
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Measuring weak magnetic field via dissipatively coupled opto-mechanical system
摘要： In this paper, we propose a scheme for the detection of weak magnetic field based on dissipatively coupled optomechanical system. The system considered here is composed of a perfect mirror and a compound mirror formed by a Michelson-Sagnac interferometer (MSI) with a movable membrane. When the transmissivity of MSI is close to zero, it sensitively depends upon the position of membrane. Under this condition, the two mirrors results in an effective Fabry-Perot interferometer (FPI) whose linewidth depends upon the position of the membrane. We show that by applying current to the membrane in the presence of magnetic field, the position of the membrane changes which in turn changes the linewidth of the effective FPI. This change can be observed in the spectrum of the output field and consequently enables us to measure weak magnetic field. Thus an optical detection technique is proposed for the detection of weak magnetic field.
关键词： Michelson-Sagnac interferometer,weak magnetic field,dissipatively coupled optomechanical system,optical detection technique,Fabry-Perot interferometer
更新于2025-09-12 10:27:22