Fluorescence spectroscopy is frequently used to analyze the concentration of fluorescent materials in solution. However, in conventional fluorescence spectroscopy, the response between the fluorescence intensity and fluorophore concentration is nonlinear at high concentrations due to uncompensated inner-filter effects (IFE). Many methods to resolve this problem have been developed in recent decades. This review introduces the methods used to correct the IFE, including direct correction and parameter correction. Relevant detection parameters, including the materials, matrices, detection limits, detection instruments and relative standard deviations, are tabulated. The advantages and limitations of these correction techniques are also discussed. Finally, the methods used to correct for the IFE are summarized, and future research directions are discussed. 相似文献
The spatial and temporal coherence of the fluorescence emission controlled by a quasi‐two‐dimensional hybrid photonic–plasmonic crystal structure covered with a thin fluorescent‐molecular‐doped dielectric film is investigated experimentally. A simple theoretical model to describe how a confined quasi‐two‐dimensional optical mode may induce coherent fluorescence emission is also presented. Concerning the spatial coherence, it is experimentally observed that the coherence area in the plane of the light source is in excess of 49 μm2, which results in enhanced directional fluorescence emission. Concerning temporal coherence, the obtained coherence time is 4 times longer than that of the normal fluorescence emission in vacuum. Moreover, a Young's double‐slit interference experiment is performed to directly confirm the spatially coherent emission. This smoking gun proof of spatial coherence is reported here for the first time for the optical‐mode‐modified emission. 相似文献
Fluorescent nanodiamonds (FNDs) are vital to many emerging nanotechnological applications, from bioimaging and sensing to quantum nanophotonics. Yet, understanding and engineering the properties of fluorescent defects in nanodiamonds remain challenging. The most comprehensive study to date is presented, of the optical and physical properties of five different nanodiamond samples, in which fluorescent nitrogen‐vacancy (NV) centers are created using different fabrication techniques. The FNDs' fluorescence spectra, lifetime, and spin relaxation time (T1) are investigated via single‐particle confocal fluorescence microscopy and in ensemble measurements in solution (T1 excepted). Particle sizes and shapes are determined using scanning electron microscopy and correlated with the optical results. Statistical tests are used to explore correlations between the properties of individual particles and also analyze average results to directly compare different fabrication techniques. Spectral unmixing is used to quantify the relative NV charge‐state (NV? and NV0) contributions to the overall fluorescence. A strong variation is found and quantified in the properties of individual particles within all analyzed samples and significant differences between the different particle types. This study is an important contribution toward understanding the properties of NV centers in nanodiamonds. It motivates new approaches to the improved engineering of NV‐containing nanodiamonds for future applications. 相似文献
Gold quantum dots (AuQDs) are employed as photosensitizers in organic thin‐film solar cells (OSCs) to improve their photoelectric conversion properties. Three types of AuQDs with different fluorescence emission wavelengths are used: blue (B‐AuQDs), green (G‐AuQDs), and red (R‐AuQDs). AuQDs are loaded into the poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) thin‐film layer of OSCs. UV–vis spectra, atomic force microscope images, current density–voltage characteristics, and impedance spectra of the fabricated devices are measured for the three aforementioned types of AuQDs. All types of AuQDs improve the photoelectric conversion properties, and the G‐AuQD‐loaded OSCs exhibit the best improvement, exhibiting an efficiency increase of 10% compared with OSCs without the AuQDs. The fluorescence/photosensitization of the AuQDs plays an important role in the enhancement of the OSCs. Finite‐difference time‐domain simulations indicate increased electric field intensity due to a small degree of AuQDs aggregation. 相似文献
Temperature measurement in biology and medical diagnostics is of great importance. Herein, a novel carbon nanodot (CND) based fluorescent nanothermometry device for spatially resolved temperature measurements is demonstrated. The fluorescence CNDs are prepared by a simple one‐pot solvothermal method using sucrose as carbon source. Resultant CNDs show stable green fluorescence at 520 nm with high quantum yield (≈6%). The fluorescence of resultant CNDs exhibits a reversible linear response to temperature in a wide range of 20–85 °C. Moreover, the temperature resolution better than 0.5 °C and high sensitive variation of ≈1.3% °C?1 are observed in a broad physiological temperature range of 20–40 °C. Therefore, the as‐prepared CNDs possess high water solubility, stable fluorescence, small size, and good biocompatibility, which make them promising candidate for thermometry and cell imaging in biological media. 相似文献
Metasurfaces, which consist of resonant metamaterial elements in the form of two‐dimensional thin planar structures, retain great capabilities in manipulating electromagnetic wave and potential applications in modifying interaction with fluorescent molecules. The metasurfaces with magnetic responses are favorable to weakening fluorescence quenching while less investigated in controlling fluorescence. In this paper, we demonstrate control over fluorescence emission by engineering the magnetic and electric modes in plasmonic metasurfaces consisting of 45‐nm‐thick gold split‐ring‐resonators (SRRs). The fluorescence emission exhibits an enhancement factor of ∼18 and is predominantly x‐polarized with assistance of the magnetic mode excited by oblique incidence with an x‐polarized electric field. The magnetic and electric modes excited by oblique incidence with a y‐polarized electric field contribute to the rotation of emission polarization with respect to the incident polarization. The results demonstrate manipulating the interaction of fluorescent emitters with different resonant modes of the SRR‐based metasurface at the nanoscale by the polarization of incident light, providing potential applications of metasurfaces in a wide variety of areas, including optical nanosources, fluorescence spectroscopy and compact biosensors.
In this letter we report further findings on the ability of an applied direct current to modulate Metal-Enhanced Fluorescence
(MEF). Fluorophores in close-proximity to just-continuous silver films (JCS) show significantly enhanced fluorescence intensities. However, when a current is applied to the films,
the enhanced fluorescence can be gated in a manner that depends on both the fluorophore concentration, the magnitude of the
applied current and the extent of the protein mono to multi-layer surface coverage. Our results are consistent and indeed
further support our previous hypothesis and model that fluorophore-metal near-field interactions can be influenced by an applied
direct current. 相似文献
Many experimental designs, in which nucleic acid conformational changes are of interest, require reliable fluorescence labeling. The appropriate fluorescence probe should have suitable optical properties and, more importantly, should not interfere with the investigated processes. In order to avoid chemical modifications the fluorescence label needs to be associated with nucleic acid via weak non-covalent interactions. There are a number of fluorescent probes that change their fluorescent properties (i.e. their quantum yield and/or spectral characteristics) upon association with nucleic acid. Such probes are frequently used to detect, visualize and follow processes involving nucleic acid and its conformational changes. In order to obtain reliable data regarding macromolecule or aggregate topology a detailed knowledge of probe–nucleic acid interactions on the molecular level is needed. In this paper we show that the association of propidium iodide with DNA alters its conformation and that it selectively labels plasmid fragments and/or its subpopulations in a concentration-dependent meaner. Another dye, PicoGreen, exhibits better properties. It labels nucleic acid uniformly and without any concentration-dependent artifacts. 相似文献
The “far‐field” effect of metal nanoparticles (NPs), when chromophores localized nearby metal NPs (typically the distance >λ/10), is an important optical effect to enhance emission in photoluminescence. The far‐field effect originates mainly from the interaction between origin emission and mirror‐reflected emission, resulting in the increased irradiative rate of chromophores on the mirror‐type substrate. Here, the far‐field effect is used to improve emission efficiency of polymer light‐emitting diodes (PLEDs). A universal performance improvement is achieved for the full visible light (red, green, blue) PLEDs, utilizing gold (Au) NPs to modify the indium tin oxide (ITO) substrates; this is shown by experimental and theoretical simulation to mainly come from the far‐field effect. The optimized distance, between the NPs and chromophores with visible light emission ranging from 400 to 700 nm, is 80–120 nm. Thus the scope of the far‐field may overlap the light‐emitting profile very well to enhance the efficiency of optoelectronic devices. The 30–40% enhancement is obtained for different color‐emitting materials through distance optimization. The far‐field effect is demonstrated to enhance device performance for materials in the full‐visible spectral range, which extends the optoelectric applications of Au NPs. 相似文献
Transition metal dichalcogenides (TMDC) are important representatives in the emerging field of two‐dimensional materials. At present their combination with molecular films is discussed as it enables the realization of van der Waals bound organic/inorganic hybrids which are of interest in future device architectures. Here, we discuss the potential use of molybdenum disulfide (MoS2) as supporting substrate for the growth of well‐defined, crystalline organic adlayers. By this means, hybrid systems between the TMDC surface and organic compounds can be prepared, allowing for the profound investigation of mutual optical and electronic coupling mechanisms. As model system, we choose pentacene and perfluoropentacene as prototypical organic semiconductors and analyze their film formation on MoS2(001) surfaces. In both cases, we observe smooth, crystalline film growth in lying molecular configuration, hence enabling the preparation of well‐defined hybrid systems. By contrast, on defective MoS2 surfaces both materials adopt an upright molecular orientation and exhibit distinctly different film morphologies. This emphasizes the importance of highly ordered TMDC surfaces with low defect density for the fabrication of well‐defined hybrid systems. 相似文献