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Proton-transfer based azides with fluorescence off–on response for detection of hydrogen sulfide. An experimental, theoretical and bioimaging study
摘要： This work describes the synthesis of photoactive proton transfer compounds based on the benzazolic core containing the azide group. The compounds present absorption in the UV region and fluorescence emission in the visible region of the spectra with large Stokes shift due to a phototautomerism in the excited state (ESIPT). The azide location on the benzazolic structure showed to present a noteworthy role on their photophysics leading to fluorescence quenching. A photophysical study was performed in the presence of NaHS to evaluate their application as H2S sensor. The methodology employed was the reduction of azides to amines using NaHS to mimic H2S, resulting in an off–on response fluorescence mechanism. The observed photophysical features were successfully used to explore the azides as fluorescent probes in biological media. In addition, DFT and TD-DFT calculations with CAM-B3LYP/cc-pVDZ and CAM-B3LYP/jun-cc-pVTZ level respectively were performed in order to understand the photophysics features of azide derivatives, where the main interest was investigate fluorescence quenching experimentally observed in the azide derivatives.
关键词： optical sensor,TD-DFT,fluorescence,ESIPT,azides
更新于2025-09-09 09:28:46
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PHIPS–HALO: the airborne Particle Habit Imaging and Polar Scattering probe – Part 1: Design and operation
摘要： The number and shape of ice crystals present in mixed-phase and ice clouds influence the radiation properties, precipitation occurrence and lifetime of these clouds. Since clouds play a major role in the climate system, influencing the energy budget by scattering sunlight and absorbing heat radiation from the earth, it is necessary to investigate the optical and microphysical properties of cloud particles particularly in situ. The relationship between the microphysics and the single scattering properties of cloud particles is usually obtained by modelling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. There is a demand to obtain both information correspondently and simultaneously for individual cloud particles in their natural environment. For evaluating the average scattering phase function as a function of ice particle habit and crystal complexity, in situ measurements are required. To this end we have developed a novel airborne optical sensor (PHIPS-HALO) to measure the optical properties and the corresponding microphysical parameters of individual cloud particles simultaneously. PHIPS-HALO has been tested in the AIDA cloud simulation chamber and deployed in mountain stations as well as research aircraft (HALO and Polar 6). It is a successive version of the laboratory prototype instrument PHIPS-AIDA. In this paper we present the detailed design of PHIPS-HALO, including the detection mechanism, optical design, mechanical construction and aerodynamic characterization.
关键词： mixed-phase clouds,PHIPS-HALO,precipitation,ice crystals,ice clouds,optical properties,radiation properties,climate system,microphysical properties,airborne optical sensor
更新于2025-09-04 15:30:14
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Product-Specific Nonlinear Characterization and Instrument for Illumination Angle Measurement With Manufacturing Defects
摘要： Popular sensors that detect the quadrant of the illumination directions are often inadequate for advanced control systems, e.g., solar trackers and heliostats. We propose a theoretical and technical framework for some sensor-specific characterization tools together with an optical instrument, which makes possible the accurate measurements in terms of the illumination angle and its angular velocity at the presence of the manufacturing errors due to rough manufacturing processes (e.g., forging and casting). In particular, a parameter identification approach is employed to identify four uncertain incline angles of sensor products with the aid of an ingenious and controllable calibration device. The angular velocity of illumination is approximately derived through a one-step backward difference function together with finite impulse response filters to reject the disturbances. The experimental results show that the sensor-specific nonlinear characteristic functions improve the accuracy of the illumination angle measurement yielded by the general nonlinear characteristic functions for the ideal sensors up to 96%, where the measurement precision with 0.07° is achieved.
关键词： parameter estimation,optical sensor,characteristic function,nonlinear optimization,Calibration
更新于2025-09-04 15:30:14