- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Variance Spectroscopy Studies of Single-Wall Carbon Nanotube Aggregation
摘要： Early stages of single-wall carbon nanotube aggregation in aqueous surfactant suspension have been investigated through combined structure-resolved fluorescence and variance spectroscopies. Following the addition of NaCl to destabilize dispersed samples, variance data revealed strong decreases in the concentrations of emitting particles, while fluorescence spectra showed only modest changes. This indicates the formation of loose aggregates in which electronic contact between individual nanotubes is too limited to perturb their emission. Variance data showed that the initial formation rates of homoaggregates (clusters of the same (n,m) species) increase superlinearly with NaCl concentration. Co-variance analysis gave complementary structure-resolved data on emissive heteroaggregates. For both types of clusters, it is found that the initial aggregation rates correlate with species particle concentrations, but show no clear dependence on nanotube structure. Variance spectroscopy can sensitively detect and characterize small loose clusters of carbon nanotube that are not observable by other spectroscopic methods.
关键词： heteroaggregates,homoaggregates,aggregation,fluorescence spectroscopy,variance spectroscopy,single-wall carbon nanotubes
更新于2025-09-23 15:21:01
-
Linear and nonlinear optical effects in biophotonic structures using classical and nonclassical light
摘要： In this perspective article, we review the optical study of different biophotonic geometries and biological structures using classical and nonlinear regime, especially highlighting the link between these morphologies and modern biomedical research. Additionally, the importance of nonlinear optical study in biological research, beyond traditional cell imaging is also highlighted and described. Finally, we present a short introduction regarding nonclassical light and describe the new future perspective of quantum optical study in biology, revealing the link between quantum realm and biological research.
关键词： linear and nonlinear spectroscopy,nonclassical light,squeezed light,optics,ghost imaging,biophotonics,fluorescence spectroscopy
更新于2025-09-23 15:21:01
-
Aggregation-Induced Emission-Based Polymer Materials: Ratiometric Fluorescence Responses Controlled by Hydrostatic Pressure
摘要： Dual fluorescence materials that exhibit controllable ratiometric changes in response to various external stimuli have attracted much attention from the viewpoints of applied material science and sensing/imaging technologies in interfaces. In the present study, we found fluorescence polymers based on aggregation-induced emission (AIE) characters. The functional AIE polymers can be converted to ratiometric fluorophores upon electronic excitation, and subsequently, their optical/photophysical properties can also be regulated by hydrostatic pressure or isotropic mechanical force. The degree of substitution (DS) of AIE branches on the polymer backbone plays critical roles in influencing the pressure-induced ratiometric fluorescence responses. The present study provides significant guidelines for developing AIE-based smart applied materials to response in hydrostatic pressure.
关键词： fluorescence spectroscopy,excited-state behavior,polyethylene,hydrostatic pressure,aggregation-induced emission,luminescence materials
更新于2025-09-23 15:21:01
-
Photophysical Properties of Fluorescent Self-Assembled Peptide Nanostructures for Singlet Oxygen Generation
摘要： In this work, a drug delivery system for perillyl alcohol based on the peptide self-assembly containing 3-(2-benzothiazolyl)-7-(diethylamino)coumarin (C6) as a fluorescent additive is obtained, and its photophysical characteristics as well as its release dynamics were studied by steady-state and time-resolved fluorescence spectroscopy. Results proved the dynamics of drug release from the peptide nanostructures and showed that the system formed by the self-assembled peptide and C6, along with perillyl alcohol, presents unique photophysical properties that can be exploited to generate singlet oxygen (1O2) upon irradiation, which is not achieved by the sole components. Through epifluorescence microscopy combined with time-correlated single photon counting fluorescence spectroscopy, the release mechanism was proven to occur upon peptide structure interconversion, which is controlled by environmental changes.
关键词： photophysical properties,perillyl alcohol,drug delivery system,time-resolved fluorescence spectroscopy,fluorescent additive,peptide self-assembly,epifluorescence microscopy,singlet oxygen generation
更新于2025-09-23 15:21:01
-
Development of laser ablation absorption spectroscopy for nuclear fuel materials: plume expansion behavior for refractory metals observed by laser-induced fluorescence imaging spectroscopy
摘要： The dynamic behavior of an ablation plume in low pressure rare gas ambient was investigated with laser-induced fluorescence imaging spectroscopy for three refractory metals, i.e. titanium, zirconium and hafnium. A comparison of the plume expansion behaviors for the species of these elements revealed an atomic weight effect on the plume structure formation. A hemispherical thin layer and cavity structure reported previously for gadolinium were observed also for these elements. It was found that the plume size increases as well as the layer thickness decreases with increasing atomic weight. For ground state atoms of Ti, substantial amount of atoms were observed even at the center of the plume. Also, the persistence of the Ti atomic plume was as long as 300 μs, which was significantly longer than the other species studied. Furthermore, the mass-dependent elemental separation was observed in the ablation plume produced from a multielement sample. These results suggest that the observed plume structure arises from the ion-electron recombination process and the recoil of the ablated species during the multiple collisions with gas atoms.
关键词： LIBS,Laser-induced fluorescence spectroscopy,Laser ablation,Ablation plume structure,Refractory metals
更新于2025-09-23 15:21:01
-
Fluorescence spectroscopy of ancient sedimentary organic matter via confocal laser scanning microscopy (CLSM)
摘要： Fluorescence spectroscopy via confocal laser scanning microscopy (CLSM) was used to analyze ancient sedimentary organic matter, including Tasmanites microfossils in Devonian shale and Gloeocapsomorpha prisca (G. prisca) in Ordovician kukersite from North American basins. We examined fluorescence emission as a function of excitation laser wavelength, sample orientation, and with respect to location within individual organic entities and in transects across bedded organic matter. Results from spectral scans of the same field of view in Tasmanites with different laser lines showed progressive red-shift in emission maxima with longer excitation wavelengths. This result indicates steady-state Tasmanites fluorescence emission is an overlapping combination of emission from multiple fluorophore functions. Stokes shift decreased with increasing excitation wavelength, further suggesting the presence of multiple fluorophore functions with different S1 → S0 transition energies. This observation also indicates that at longer excitation wavelengths, less absorbed light energy is dissipated via collisional transfer than at shorter excitation wavelengths and may suggest fewer polar functions are preferentially absorbing. Confirming earlier results, emission spectra observed from high fluorescence intensity regions (fold apices) in individual Tasmanites are blue-shifted relative to emission from other locations in the same microfossil. We suggest high intensity emission is from photoselective alignment of polarized excitation with the fluorophore absorption and emission transition moment. The blue shift observed in regions of high intensity emission may be due to relative absence or realignment of polar species, e.g., bridging ether or ester functions, although variations in O abundance could not be confirmed with preliminary time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis. Tasmanites occurring in consolidated sediments are flattened from original spherical morphology and, in optical microscopy, this burial deformation results in generally parallel extinction (strain-influenced) and positive elongation. The deformation also induces fluorescence anisotropy observed as variations in emission wavelength when individual Tasmanites are measured from their long axis parallel to bedding, whereas this effect is absent in bedding-normal view. Transects from G. prisca-rich source layers into adjacent reservoir layers show decrease in fluorescence intensity and spectral red-shift (increase in full-width half-maximum with increasing red portion of the half-width). These results may suggest an increase in fluorescence quenching across the source-to-reservoir transition zone, consistent with an increase in aromaticity following petroleum expulsion and migration. These observations are supported by increasing reflectance values measured across similar micro-scale transects. Our results highlight the applicability of CLSM as a broad and under-utilized approach for the characterization of sedimentary organic matter and are discussed with perspective toward petroleum processes and thermal indices research.
关键词： Gloeocapsomorpha prisca,Confocal laser scanning microscopy,Tasmanites,Petroleum processes,Fluorescence spectroscopy,Sedimentary organic matter,Thermal indices
更新于2025-09-23 15:21:01
-
Understanding the Microscopic Behavior of Binary Mixtures of Ionic Liquids Through Various Spectroscopic Techniques
摘要： In recent times it has been shown that certain binary mixture of pure ionic liquids having appropriate chemical composition can behave like a new chemical entity. However, current knowledge about the microscopic behavior of these interesting systems is rather limited. The present study is undertaken with an objective to understand the microscopic behavior in terms of intermolecular interaction, structure and dynamics of these systems. In the present study, few (IL+IL) mixtures are chosen with a common cation and a variation of anion. The investigations are also carried out by taking individual pure ILs so that the difference in behavior between pure IL and (IL+IL) mixtures are understood. Initially the systems have been investigated by studying the thermophysical properties of the concerned mixtures. Synergistic effect between combining pure ILs through photochromism has also been studied. These mixtures have been investigated further through steady state and time resolved fluorescence spectroscopy, electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR) and fluorescence correlation spectroscopy (FCS). Interestingly, time-resolved fluorescence data also pointed out that (IL+IL) mixtures are not only spatially heterogeneous but they are dynamically heterogeneous too. EPR measurements have suggested that the micro-polarity (ET(30)) of (IL+IL) mixture is close to aliphatic polyalcohol. Measurements of translational diffusion coefficients of the diffusing species through NMR and FCS studies have provided idea about the nano-structural organization within (IL+IL) binary mixtures. The analysis of data essentially reveals that the mixtures of ILs that are used in the current study do not behave like a non-ideal solution. The behavior of the IL mixtures is observed to be more like quasi-ideal type.
关键词： thermophysical properties,binary mixtures,EPR,FCS,fluorescence spectroscopy,NMR,Ionic liquids,photochromism,spectroscopic techniques
更新于2025-09-23 15:21:01
-
[IEEE 2018 37th Chinese Control Conference (CCC) - Wuhan (2018.7.25-2018.7.27)] 2018 37th Chinese Control Conference (CCC) - Qualitative Elemental Analysis of Minerals Based on Energy Dispersive X - ray Fluorescence Spectrometry
摘要： The research of miniaturized XRF/XRD analyzers are carried out in this paper, especially the qualitative analysis based on EDXRF, a miniaturized energy dispersive X-ray ?uorescence spectrometry platform is designed and a qualitative elemental analysis software based on Android operating system is developed. The elemental qualitative analysis software can preprocess the X-ray feature spectrum by background eliminationsmoothing and energy coef?cient calibration, after these pretreatments, the main elements of the sample can be analyzed. The experimental results show that the qualitative elemental analysis platform proposed in this paper can measure the elements of Al to Au in the periodic table, besides, the detection accuracy of multiple samples is higher than 97%. The mineral qualitative elemental analysis software proposed in this paper can be applied to any portable analysis platform based on Android operating system, moreover, it will spur advances in the development of the miniaturization and intelligent X-ray ?uorescence spectrometer.
关键词： Fluorescence spectroscopy,EDXRF,Qualitative elemental analysis
更新于2025-09-23 15:21:01
-
Multi-dimensional fluorescence spectroscopy coupled with chemometrics in rapid antibiotic detection and discrimination
摘要： Antibiotic residues in animal-derived foods pose risk to human health including chemical poisoning and antimicrobial resistance, and therefore, constant monitoring throughout the food supply chain is important. In the present study multi-dimensional fluorescence spectroscopy (3D and 2D) coupled with chemometric tools were tested for potential application to detect, discriminate and quantify penicillin G (PG), sulfadiazine (SF) and tetracycline (TC) in milk by direct measurement. Qualitative and quantitative calibration models were developed for prediction of antibiotic residues. Results demonstrated optimal discrimination of milk samples on the basis of antibiotic type and concentration with close to 100% of accuracy. Negative correlation between antibiotic concentration and fluorescence peak height was displayed (r ≥ 0.963 and p ≤ 0.002). A great potential for quantitative antibiotic determination was established with R2 > 0.9 and low standard errors of estimation indicating acceptable precision for the developed technique. Fluorescence spectroscopy demonstrated high specificity and sensitivity with detection limit below the maximum residue limit of PG, SF and TC in milk. Therefore, fluorescence spectroscopy can be used as an alternative method for rapid screening of antibiotic residues in milk at collection centers and processing plants to ensure product quality and safety.
关键词： Rapid detection,Antibiotics,Discrimination,Fluorescence spectroscopy,Milk
更新于2025-09-23 15:19:57
-
Ice Confinement-Induced Solubilization and Aggregation of Cyanonaphthol Revealed by Fluorescence Spectroscopy and Lifetime Measurements
摘要： When an aqueous salt solution freezes, a freeze concentrated solution (FCS) separates from ice. The properties of the FCS may differ from those of a supercooled bulk solution of the same ionic strength at the same temperature. The fluorescence and lifetime characteristics of 6-cyano-2-naphthol (6CN) were studied in frozen NaCl solutions to provide an insight into the solution properties of the FCS. While the photoacidity of 6CN in an FCS is similar to that in solution, several anomalous behaviors are observed. Fluorescence spectra indicate that the solubility of 6CN is significantly enhanced in the FCS (50 mM or higher) compared to that in bulk NaCl solution, where the solubility limit is 250 μM. The high solubility induces aggregation of 6CN in the FCS, which is not detected in bulk solutions. This trend becomes marked as the initial NaCl concentration decreases, that is, the FCS is confined in a small space. The fluorescence lifetimes of 6CN in the FCS support the spectroscopy results. In addition to the species identified by fluorescence spectroscopy, excimers are assigned from lifetime measurements in the FCS. The excimer formation is also a result of the enhanced solubility of 6CN in the FCS.
关键词： solubility enhancement,aggregation,lifetime measurements,excimer formation,6-cyano-2-naphthol,freeze concentrated solution,Fluorescence spectroscopy
更新于2025-09-23 15:19:57