- 标题
- 摘要
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- 实验方案
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Characterization of a double Time-Of-Flight detector system for accurate velocity measurement in a storage ring using laser beams
摘要： The Isochronous Mass Spectrometry (IMS) is a powerful tool for mass measurements of exotic nuclei with half-lives as short as several tens of micro-seconds in storage rings. In order to improve the mass resolving power while preserving the acceptance of the storage ring, the IMS with two Time-Of-Flight (TOF) detectors has been implemented at the storage ring CSRe in Lanzhou, China. Additional velocity information beside the revolution time in the ring can be obtained for each of the stored ions by using the double TOF detector system. In this paper, we introduced a new method of using a 658 nm laser range finder and a short-pulsed ultra-violet laser to directly measure the distance and time delay difference between the two TOF detectors which were installed inside the 10?11 mbar vacuum chambers. The results showed that the distance between the two ultra-thin carbon foils of the two TOF detectors was ranging from 18032.5 mm to 18035.0 mm over a measurable area of 20×20 mm2. Given the measured distance, the time delay difference which comes with signal cable length difference between the two TOF detectors was measured to be ??????????????1?2 = 99(26) ps. The new method has enabled us to use the speed of light in vacuum to calibrate the velocity of stored ions in the ring. The velocity resolution of the current double TOF detector system at CSRe was deduced to be ??(??)∕?? = 4.4 × 10?4 for laser light, mainly limited by the time resolution of the TOF detectors.
关键词： Ultra-high vacuum,Ultra-thin carbon foil,TOF detectors,Velocity measurement,Laser range-finder,ps-pulsed UV laser
更新于2025-11-25 10:30:42
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Direct Imaging of Current‐Induced Transformation of a Perovskite/Electrode Interface
摘要： Formamidinium-lead-iodide (FAPbI3) perovskite films are subjected to a long-term action of the constant electrical current in the dark, using planar vacuum-deposited gold electrodes. The current-induced transformation is monitored by the time-of-flight secondary ion mass spectrometry (ToF-SIMS) mapping complemented by microscopic, spectroscopic methods, and X-ray diffraction. The migration of chemical species inside the lateral interelectrode gap is clearly visualized by ToF-SIMS. Those species correspond to both electrode material and perovskite itself, so that the perovskite/electrode interface becomes disrupted. As a result, the interelectrode gap shrinks, which is reflected in the surface images.
关键词： interfaces,dark current,gold electrodes,perovskites,ToF-SIMS mapping
更新于2025-11-25 10:30:42
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Morphology Tuning of ZnO/P3HT/P3HT-b-PEO Hybrid Films Deposited via Spray or Spin Coating
摘要： Hybrid films of zinc oxide (ZnO) and poly(3-hexylthiophen-2,5-diyl) (P3HT) show promising characteristics for application in hybrid bulk heterojunction solar cells (HBSCs). However, the incompatibility of ZnO and P3HT may lead to a reduced interface area, thus reducing the probability of exciton separation and consequently lowering solar cells efficiencies. Here, a diblock copolymer P3HT-b-poly(ethylene oxide) (PEO) is introduced to improve the interface between ZnO and P3HT. ZnO is synthesized via a block copolymer assisted sol-gel approach and the used zinc precursor is directly incorporated into the PEO blocks. Thus, the possibility of aggregation is reduced for both, the inorganic and the organic components and a good intermixing is ascertained. Two deposition methods, namely spray and spin coating are compared with respect to the resulting film structure, which is investigated with scanning electron microscopy (SEM) and time-of-flight grazing-incidence small-angle neutron scattering (TOF-GISANS) measurements. Both, the surface and inner morphologies reveal that the spin coated samples possess smaller and less diverse domain sizes than the sprayed films. Due to the advantage of spray coating in large-scale production, the morphology of the sprayed samples is tailored more meticulous by changing the weight fraction of ZnO in the films. The sprayed hybrid films show smaller domains and less aggregation with decreasing amount of ZnO. This reveals that both, the deposition method and composition of the ZnO/P3HT/P3HT-b-PEO hybrid films play an important role for the film morphology and thus for improving the performance of HBSCs in future application.
关键词： spray coating,morphology,spin coating,ZnO/P3HT/P3HT-b-PEO,TOF-GISANS
更新于2025-11-14 15:19:41
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FT-Raman Analyses of Blue Dyes Stuff Common in Swedish Folk Art from H?lsingland during 18th and 19th Century
摘要： The overall aim of this study is to gain a better understanding of the historic use of woad in Sweden in the 18th and 19th centuries. A key question is, whether it is possible to distinguish between indigo from woad and exotic indigo using Raman spectroscopy? Reference samples prepared according to historic recipes using woad, exotic indigo, logwood and brazilwood - were used to dye different textile fibres - cotton, wool and linen. In addition, various reference compounds - indigotin, indirubin, kaempferol, luteolin, 3-hydroxyflavone and tryptanthrin - as well as the ‘flower’ of the woad dye bath were analysed to identify specific fingerprint regions for each compound. Blue threads from four historic textiles - a skirt and three rag balls - from the region of H?lsingland were then analysed in comparison to the references. A specific peak at 993 cm-1 was identified in the spectra taken from the flower of the woad vat, which we suggest possibly arises from 3-hydroxyflavone. DSA-ToF-MS analysis suggests flavone- glycosides as possible candidates. However, cellulosic substrates show a broad vibration at 999 cm-1 overlapping the flavone signature, thus rendering it non-diagnostic, but it might be possible to use this peak in Raman analyses supported by mass spectrometry to distinguish between indigo from woad and exotic indigo if the substrate is wool or if it is a pigment. Raman analyses of the historic samples identify the colourants as indigo and possibly woad and logwod mixed with brazilwood.
关键词： DSA-Tof-MS,Dyestuff,Lac pigments,FT-Raman,Colouring matters
更新于2025-11-14 15:16:37
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Thermal atomic layer deposition of AlOxNy thin films for surface passivation of nano-textured flexible silicon
摘要： Aluminum oxynitride (AlOxNy) films with different nitrogen concentration are prepared by thermal atomic layer deposition (ALD) for flexible nano-textured silicon (NT-Si) surface passivation. The AlOxNy films are shown to exhibit a homogeneous nitrogen-doping profile and the presence of an adequate amount of hydrogen, which is investigated by Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA). The effective minority carrier lifetimes are measured after the NT-Si surface passivation; the minimum surface recombination velocity (SRV) of 5 cm-s-1 is achieved with the AlOxNy film in comparison to the Al2O3 and AlN films (SRV of 7–9 cm-s-1). The better SRV with AlOxNy film is due to the collective effect of field-effect passivation by the presence of fixed negative charges, and chemical passivation by the presence of hydrogen within the film. The capacitance-voltage, and conductance measurements also are carried out using metal-oxide-semiconductor structure to determine the fixed negative charge density (Nf,ox), and defect density of states (Dit) in the AlOxNy films. The better surface passivation is attributed to unusually large Nf,ox of ~6.07 × 1012 cm-2, and minimal Dit of ~1.01 × 1011 cm-2-eV-1 owing to the saturation of Si dangling bonds by the hydrogen within the AlOxNy film matrix after the annealing step.
关键词： Surface passivation,Time-of-flight elastic recoil detection analysis (ToF-ERDA),Aluminum oxynitride,Thermal atomic layer deposition,Black flexible silicon
更新于2025-10-22 19:40:53
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Confining analyte droplets on visible Si pillars for improving reproducibility and sensitivity of SALDI-TOF MS
摘要： We present a universal method to efficiently improve reproducibility and sensitivity of surface-assisted laser desorption/ionization time of flight mass spectrometry (SALDI-TOF MS). In this method, the Si pillar array with unique surface wettability is used as substrate for ionizing analyte. The Si pillar is fabricated based on the combination of photolithography and metal-assisted chemical etching, which is of hydrophilic top and hydrophobic bottom and side wall. Based on the surface wettability of the Si pillar, a droplet of an aqueous analyte solution can be confined on the top of the Si pillar. After evaporation of solvent, an analyte deposition spot is formed on the top of Si pillar. The visible size of the Si pillar allows the sample spot to be easily found. Meanwhile, the diameter of the Si pillar is smaller than that of the laser, allowing the observation of all analyte molecules under one laser shot. Therefore, the reproducibility and sensitivity are highly improved with this method, which allows for the quantitative analysis. Furthermore, this method is applicable for different analytes dissolved in water, including amino acids, dye molecules, polypeptides, and polymers. The application of this substrate is demonstrated by analyzing real samples at low concentration. It should be a promising method for sensitive and reproducible detection for SALDI-TOF MS.
关键词： Improving reproducibility and sensitivity,SALDI-TOF MS,Visible Si pillars,Minimizing sample spots,Universality
更新于2025-09-23 15:23:52
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Resonance enhanced multiphoton ionisation (REMPI) detection of Cl( <sup>2</sup> P <sub/>j</sub> ) atom in the photodissociation of halogenated pyrimidines at 235 nm: role of triplet states
摘要： The dynamics of chlorine atom (2Pj) formation in the photodissociation process of halogen substituted pyrimidines, namely, 2,4,6-trichloropyrimidine and 5-chloro-2,4,6-trifluoropyrimidine have been studied around 235 nm using Resonance Enhanced Multiphoton Ionisation Time-of-Flight Mass Spectrometry technique. For the chlorine atom dissociation channel, we have determined the translational energy distribution, the recoil anisotropy parameter, β, and the spin–orbit branching ratio. In both the molecules, the TOF profiles for Cl (2P3/2) and Cl* (2P1/2) are found to be independent of laser polarisation suggesting a zero value for β, within the experimental uncertainties. For 2,4,6-trichloropyrimidine, the average translational energies for Cl and Cl* elimination channels are determined to be 6.0 ± 1.2 and 7.0 ± 1.5 kcal/mol, respectively. Similarly, for 5-chloro-2,4,6-trifluoropyrimidine, the average translational energies for Cl and Cl* elimination channels are determined to be 6.5 ± 1.2 and 7.9 ± 1.6 kcal/mol, respectively. Computational calculations are performed to generate the potential energy curves along the dissociating C-Cl bond using equation of motion coupled cluster with single and double excitations (EOM-CCSD) method. Computational studies suggest the role of triplet states in the photodissociation process forming the Cl atom.
关键词： REMPI-TOF,halogenated pyrimidines,translational energy,spin-orbit ratio,Photodissociation dynamics
更新于2025-09-23 15:23:52
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Compact Real-Time Inter-Frame Histogram Builder for 15Bits High-Speed ToF-Imagers based on Single-Photon Detection
摘要： Time-of-flight image sensors based on single-photon detection, i.e. SPADs, require some filtering of pixel readings. Accurate depth measurements are only possible if the jitter of the detector is mitigated. Moreover, the time stamp needs to be effectively separated from uncorrelated noise such as dark counts and background illumination. A powerful tool for this is building a histogram of a number of pixel readings. Future generation of ToF imagers are seeking to increase spatial and temporal resolution along with the dynamic range and frame rate. Under these circumstances, storing the complete histogram for every pixel becomes practically impossible. Considering that most of the information contained by the histogram represents noise, we propose a highly efficient method to store just the relevant data required for ToF computation. This method makes use of the shifted inter-frame histogram (SifH). It requires a memory as low as 128 times smaller than storing the complete histogram if the pixel values are coded on up to 15 bits. Moreover, a fixed 28 words memory is enough to process histograms containing up to 215 bins. In exchange, the overall frame rate only decreases to one half. The hardware implementation of this algorithm is presented. Its remarkable robustness for a low SNR of the ToF estimation is demonstrated by Matlab simulations and FPGA implementation using input data from a SPAD camera prototype.
关键词： shifted inter-frame histogram (SifH),single-photon avalanche-diode (SPAD),real-time time-of-flight (ToF) estimation,ToF image sensor
更新于2025-09-23 15:22:29
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Chemical imaging of buried interfaces in organic-inorganic devices using FIB-ToF-SIMS
摘要： Organic-inorganic hybrid materials enable the design and fabrication of new materials with enhanced properties. The interface between the organic and inorganic materials is often critical to the device’s performance and therefore chemical characterization is of significant interest. Since the interfaces are often buried, milling by focused ion beams (FIB) to expose the interface is becoming increasingly popular. Chemical imaging can subsequently be obtained using secondary ion mass spectrometry. However, the FIB milling process damages the organic material. In this study, we make an organic-inorganic test structure to develop a detailed understanding of the processes involved in FIB milling and SIMS imaging. We provide an analysis methodology that involves a “clean-up” process using sputtering with an argon gas cluster ion source to remove the FIB induced damage. The methodology is evaluated for two additive manufactured devices, an encapsulated strain sensor containing silver tracks embedded in a polymeric material and a copper track on a flexible polymeric substrate created using a novel nanoparticle sintering technique.
关键词： FIB,additive manufacturing,hybrid interfaces,ToF-SIMS,polymer,Argon cluster,milling
更新于2025-09-23 15:22:29
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[IEEE 2018 5th IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace) - Rome, Italy (2018.6.20-2018.6.22)] 2018 5th IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace) - Characterization and Testing of a High-Resolution Time-of-Flight Camera for Autonomous Navigation
摘要： This paper presents the results of research activities carried out to characterize and test the operation of a latest generation commercial, high-resolution Time-of-Flight (TOF) camera. The aim is to preliminary evaluate the achievable performance as well as potential limitations related to the use of this instrument for autonomous navigation purposes. Two fields of investigation have been identified: autonomous navigation of Unmanned Aerial Vehicles flying in GPS-denied environments; autonomous relative navigation between non-cooperative space objects. With reference to these applications, first, a metrological characterization has been operated within a laboratory setup. Second, experimental tests have been carried out by processing point clouds acquired by the TOF sensor with state-of-the-art algorithms (for depth-based odometry and non-cooperative pose determination, respectively).
关键词： depth-based odometry,non-cooperative pose determination,TOF camera,autonomous navigation,metrological characterization
更新于2025-09-23 15:22:29