Ye Zhu, Juefei Zhou, Mark G. Kuzyk
We report on the dynamics of photodegradation and subsequent recovery of two-photon fluorescence in a dye-doped polymer. The energy dependence suggests that photo-degradation is a linear process while recovery is entropic. Such recovery could be useful to high-intensity devices such as two-photon absorbers, which can be used in many applications.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
继续探索
Reversible photodegradation is a process that has been observed in several dye molecules, but the underlying mechanisms are not still well understood. In this contribution, we characterize a series of anthraquinone dyes to determine how self-healing depends on molecular structure. Past studies have used probing techniques that rely on linear absorption, two-photon fluorescence, and amplified spontaneous emission. Each of these probes provide an indirect measure of the populations of the damaged and undamaged species, requiring calibrations or assumptions to be made that might affect the accura…
The mechanism of reversible photodegradation of 1-substituted aminoanthraquinones doped into poly(methyl methacrylate) and polystyrene is investigated. Time-dependent density functional theory is employed to predict the transition energies and corresponding oscillator strengths of the proposed reversibly- and irreversibly-damaged dye species. Ultraviolet-visible and Fourier transform infrared (FTIR) spectroscopy are used to characterize which species are present. FTIR spectroscopy indicates that both dye and polymer undergo reversible photodegradation when irradiated with a visible laser. Thes…
We use amplified spontaneous emission (ASE) and linear absorption spectroscopy to study the mechanisms of reversible photodegradation of 1-amino-2-methylanthraquinone (disperse orange 11-DO11) in solid poly(methyl methacrylate). Measurements as a function of intensity, concentration, and time suggest that ASE originates in a state (be it a tautomer or a vibronic level) that can form a dimer or some other aggregate upon relaxation, which through fluorescence quenching leads to degradation of the ASE signal. Whatever the degradation route, a high concentration of DO11 is required and the polymer…
One of the fundamental difficulties in implementing organic dyes in random lasers is irreversible photodegradation of the dye molecules, leading to loss of performance and the need to replace the dye. We report the observation of self-healing after photodegradation in a Rhodamine 6G dye and nanoparticle doped polyurethane random laser. During irradiation we observe two distinct temporal regions in which the random lasing (RL) emission first increases in intensity and redshifts, followed by further redshifting, spectral broadening, and decay in the emission intensity. After irradiation the emis…
We model the effect of pump depletion on reversible photodegradation using the extended domain model[Anderson and Kuzyk, arXiv:1309.5176v1, 2013] and the Beer-Lambert law. We find that neglecting pump absorption in the analysis of the linear optical transmittance leads to an underestimate of the degree and rate of photodegradation. The model is used to accurately measure the molecular absorbance cross sections of the three species involved in photodegradation of disperse orange 11 dye in (poly)methyl-methacralate polymer (DO11/PMMA). Finally we find that the processing history of a dye-doped p…
Using transmittance imaging microscopy we measure the wavelength dependence of reversible photodegradation in disperse orange 11 (DO11) dye-doped (poly)methyl-methacrylate (PMMA). The reversible and irreversible inverse quantum efficiencies (IQEs) are found to be constant over the spectral region investigated, with the average reversible IQE being $\overline{B}_α= 8.70 (\pm 0.38)\times 10^5$ and the average irreversible IQE being $\overline{B}_ε= 1.396 (\pm 0.031)\times 10^8$. The large difference between the IQEs is hypothesized to be due to the reversible decay channel being a direct decay m…
We report the observation of intensity feedback random lasing at 645 nm in Disperse Orange 11 dye-doped PMMA (DO11/PMMA) with dispersed ZrO$_2$ nanoparticles (NPs). The lasing threshold is found to increase with concentration, with the lasing threshold for 0.1 wt\% being $75.8 \pm 9.4$ MW/cm$^2$ and the lasing threshold for 0.5 wt\% being $121.1 \pm 2.1$ MW/cm$^2$, with the linewidth for both concentrations found to be $\approx 10$ nm. We also consider the material's photostability and find that it displays fully reversible photodegradation with the photostability and recovery rate being great…
The influence of an applied electric field on reversible photodegradation of disperse orange 11 (DO11) doped into PMMA is measured using digital imaging and conductivity measurements. Correlations between optical imaging, which measures photodegradation and recovery, and photoconductivity enables an association to be made between the damaged fragments and their contribution to current, thus establishing that damaged fragments are charged species, or polarizable. Hence, the decay and recovery process should be controllable with the applications of an electric field. Indeed, we find that the dye…
Using a white light interferometric microscope (WLIM) we measure the photodamage induced change in the complex index of refraction of disperse orange 11 (DO11) dye-doped (poly)methyl-methacrylate. We find that the change in the imaginary part of the refractive index is consistent with previous measurements of photodamage-induced absorbance change. Additionally, we find that the change in the real refractive index can be separated into a component due to damage to the dye molecules and a component due to irreversible damage to the polymer.
Temperature dependent photodegradation and recovery studies of Dipserse Orange 11 (DO11) dye dissolved in poly(methyl methacrylate) and polystyrene polymer hosts are used as a test of the recently proposed correlated chromophore domain model.[1] This model posits that dye molecules form domains or aggregates. The nature of aggregation or how it mediates self healing is not yet well understood. In this paper we present qualitative evidence that supports the hypothesis that the dye molecules undergo a change to a tautomer state with higher dipole moment and hydrogen bond with the amines and keto…
By using specially designed nanoparticles scatterers which prevents photodegradation of the dye, we present clear demonstration of replica symmetry break and a photonic paramagnetic to spin-glass phase transition in a random laser operating in the incoherent feedback regime based on ethanol solution of Rhodamine 6G and amorphous TiO2 nanoparticles.
In this work, we show that reversible photodegradation of Disperse Orange 11 doped in PMMA is not due to dye diffusion - a common phenomenon observed in many dye-doped polymers. The change in linear absorbance due to photodegradation of the material shows an isobestic point, which is consistent with the formation of a quasi-stable damaged species. Spatially-resolved amplified spontaneous emission and fluorescence, both related to the population density, are measured by scanning the pump beam over a burn mark. A numerical model of the time evolution of the population density due to diffusion is…
All observations of photodegradation and self healing follow the predictions of the correlated chromophore domain model. [Ramini et.al. Polym. Chem., 2013, 4, 4948.] In the present work, we generalize the domain model to describe the effects of an electric field by including induced dipole interactions between molecules in a domain by means of a self-consistent field approach. This electric field correction is added to the statistical mechanical model to calculate the distribution of domains that are central to healing. Also included in the model are the dynamics due to the formation of an irr…
We have developed a white light interferometric microscope (WLIM), which can spatially resolve the change in the complex index of refraction and apply it to study reversible photodegradation of 1,4-Diamino-9,10-anthraquinone doped into (poly)methyl methacrylate. The measured change in absorbance is consistent with standard spectrometer measurements. The refractive index of a pristine sample measured with the WLIM is also found to be consistent with the spectrum found by independent means (F. Yakuphanoglu and B. Senkal, Electrical conductivity, photoconductivity, and optical properties of poly(…
We used fluorescence spectroscopic measurements as a probe to study the self-healing properties of anthraquinone derivative molecules doped in poly(methyl methacrylate) (PMMA). 2,4-dibromo anthraquinone dye doped in PMMA recovers after photodegradation. Its dynamics differs from other anthraquinone derivative molecules. This could be due to the relatively heavier bromine atom attached to one of the carbon atoms of the benzene ring. In this paper, we will discuss the self-healing properties of 2,4-dibromo anthraquinone doped in PMMA matrix. We also tested the correlated chromophore domain model…
Investigation of variation in fluorescence intensity from rhodamine 6G Dye
该研究通过低功率激光激发罗丹明6G染料溶液，观察荧光先增强后衰减及峰值蓝移，模拟揭示光漂白涉及所有能态，并测得不同阶段峰值移动速率。
Electromagnetic coupling between subradiant plasmons and dye molecular excitons analyzed by spectral changes in ultrafast surface-enhanced fluorescence
研究通过超快表面增强荧光光谱变化分析亚辐射等离子体与染料分子激发态的电磁耦合，利用电磁增强因子评估耦合强度，结合耦合振子模型揭示静态与动态光谱特性。
Plasmonically enhanced fluorescence is a widely studied and applied phenomenon, however only a comparative theoretical and experimental analyses of coupled fluorophores and plasmonic nanoresonators makes it possible to uncover, how this phenomenon can be controlled. A numerical optimization method was applied to design configurations that are capable of resulting in an enhancement of excitation and emission, moreover of both phenomena simultaneously in coupled Cy5 dye molecule and gold nanorod systems. Parametric sensitivity studies revealed, how the fluorescence enhancement depends on the mol…
One of the primary difficulties in the implementation of organic-dye-based random lasers is the tendency of organic dyes to irreversibly photodecay. In this letter we report the observation of "reversible" photodegradation in a Rhodamine 6G and ZrO$_2$ nanoparticle doped polyurethane random laser. We find that during degradation the emission broadens, redshifts, and decreases in intensity. After degradation the system is observed to self-heal leading to the emission returning to its pristine intensity, giving a recovery efficiency of 100%. While the peak intensity fully recovers, the process i…
Theoretical Analysis of Solvent Effect on NAPBr Dye's Two-photon Absorption Ability and Non-Radiative Transition in Lipid Droplets Detection
本文通过理论分析揭示了溶剂效应对NAPB r染料几何结构、非辐射跃迁及空穴-电子分布的影响机制，并发现中等介电常数溶剂能最佳平衡双光子吸收与荧光发射能力，为开发AIE型高效TPA分子提供参考。
Tunable composite materials with interesting physical behavior can be designed through integrating unique optical properties of solid nanostructures with the facile responses of soft matter to weak external stimuli, but this approach remains challenged by their poorly controlled co-assembly at the mesoscale. Using scalable wet chemical synthesis procedures, we fabricated anisotropic gold-silica-dye colloidal nanostructures and then organized them into the device-scale (demonstrated for square inch cells) electrically tunable composites by simultaneously invoking molecular and colloidal self-as…
We propose to achieve super-resolution in far-field imaging by use of dual-dye-doped nanoparticles. The nanoparticles with a diameter of a few nanometers are co-doped with two types of dye molecules, namely, Cy3 and Cy5, at a controllable ratio. Due to the short distances between the dye molecules confined in the nanoparticles, Forster resonant energy transfer can occur between the Cy3 and Cy5 molecules with high efficiency. Therefore, the Cy5 molecules can quench the fluorescence emission from the Cy3 molecules in the outer region of focal spot of the excitation beam, thereby enhancing the re…
Collective Blinking of Upconversion Emission in Lanthanide-doped Nanocrystals
本研究发现单个镧系掺杂纳米晶体内数千个镧系离子的上转换发光存在可调控的集体闪烁，阐明其机制并实现1.2纳米分辨率的超分辨成像，为相关领域提供新策略。
We present a rapid-scanning approach to fluorescence-detected two-dimensional electronic spectroscopy that combines acousto-optic phase-modulation with digital lock-in detection. The approach shifts the signal detection window to suppress 1/f laser noise and enables interferometric tracking of the time delays to allow for correction of spectral phase distortions and accurate phasing of the data. This use of digital lock-in detection enables acquisition of linear and nonlinear signals of interest in a single measurement. We demonstrate the method on a laser dye, measuring the linear fluorescenc…
Spectra of spin-forbidden and spin-allowed transitions in the mixed b$^3Π_u$ ~ A$^1Σ_u^+$ state of Na$_2$ are measured separately by two-photon excitation using a single tunable dye laser. The two-photon excitation produces Na*(3p) by photodissociation, which is easily and sensitively detected by atomic fluorescence. At low laser power, only the A$^1Σ_u^+$ state is excited, completely free of triplet excitation. At high laser power, photodissociation via the b$^3Π_u$ triplet state intermediate becomes much more likely, effectively "switching" the observations from singlet spectroscopy to tripl…
Two-photon absorption (TPA) fluorescence of biomarkers has been decisive in advancing the fields of biosensing and deep-tissue in vivo imaging of live specimens. However, due to the extremely small TPA cross section and the quadratic dependence on the input photon flux, extremely high peak-intensity pulsed lasers are imperative, which can result in significant photo- and thermal-damage. Previous works on entangled TPA (ETPA) with spontaneous parametric down-conversion (SPDC) light sources found a linear dependence on the input photon-pair flux, but are limited by low optical powers, along with…
Rational Designing of Anthocyanidins-Directed Near-Infrared Two-Photon Fluorescence Probes
本文研究了不同骨架花青素的光物理性质，通过烷基环化、氮丁环和扩展π共轭抑制TICT效应，设计了新型双光子荧光探针2a-n，其中2a-3展现出长发射波长、大TPA截面和Stokes位移，适用于高分辨率NTR检测。
Total internal reflection fluorescence (TIRF) microscopy and its variants are key technologies for visualizing the dynamics of single molecules or organelles in live cells. Yet, truely quantitative TIRF remains problematic. One unknown hampering the interpretation of evanescent-wave excited fluorescence intensities is the undetermined cell refractive index (RI). Here, we use a combination of TIRF excitation and supercritical angle fluorescence emission detection to directly mea-sure the average RI in the 'footprint' region of the cell, during imaging. Our RI measurement is based on the determi…
We have fabricated layered nanocomposite consisting of a nanoporous anodic alumina sublayer (AOA), an ultrathin metal-containing polymer Langmuir-Blodgett (LB) film coating AOA, and multi-walled carbon nanotube (MCNT) - bundles which are arranged on the LB-film. MCNTs were preliminarily chemically modified by carboxyl groups and functionalized by stearic acid. We have experimentally observed an enhancement of Raman light scattering on surface plasmons in the LB-monolayers. This enhancement is due to charge and energy transfer. We demonstrate that propidium iodide (PI) fluorescence is quenched …
Scanning microphotoluminescence is used to characterise the fluorescence from a dye-loaded polymer deposited on a 5 x 5 nanoantenna dipole array. Vertical and horizontal scans show anisotropic emission patterns.
Flexible Physical Unclonable Functions based on non-deterministically distributed Dye-Doped Fibers and Droplets
本文提出利用静电纺丝和静电喷雾技术制备染料掺杂的柔性聚合物薄膜，通过荧光液滴随机分布、特征光谱和挑战-响应对协议实现三级防伪认证，为日常商品提供低成本且不可克隆的防伪标签。
Laser Pulse Diagnostics of Ultrafast <8 fs Pulses Through Two-Photon Absorption Fluorescence In Liquid Media -- The Role of GVD and Third-Order Dispersion
本研究利用液体中双光子吸收荧光法，结合自主开发的数值算法，实现了<8 fs超快激光脉冲的色散测定与时间轮廓表征，方法低成本、鲁棒性强，对准灵敏度优于传统方法。
In this letter we report for the first time the possibility of visualizing an atomizing spray by simultaneously recording X-ray absorption and 2- photon laser-induced fluorescence imaging. This unique illumination/detection scheme was made possible thanks to the use of soft X-rays emitted from a laser-driven X-ray source. An 800 mJ laser pulse of 38 fs duration is used to generate an X-ray beam with up to 4.10^8 photons ranging from 1 to 10 keV; allowing projection radiography of water jets generated by an automotive port fuel injector. In addition, a fraction of the laser pulse (approximately…
Optical tweezers assisted coupling of nematic droplets to gold nanoparticle cluster: effect on whispering gallery modes
本研究利用光学镊将向列滴状液晶与金纳米粒子簇耦合，实现对 whispering gallery modes 的调控，展示了通过动态耦合实现光子-等离子体耦合的高效方法。
Fluorescence Lifetime Hong-Ou-Mandel Sensing
本文提出基于光子聚束统计的 Hong–Ou–Mandel 荧光寿命传感，将分辨率提升至 0.1–1 皮秒，并通过染料和甘油/水黏度测量验证其应用价值。
The detection of single molecules has facilitated many advances in life- and material-sciences. Commonly, it founds on the fluorescence detection of single molecules, which are for example attached to the structures under study. For fluorescence microscopy and sensing the crucial parameters are the collection and detection efficiency, such that photons can be discriminated with low background from a labeled sample. Here we show a scheme for filtering the excitation light in the optical detection of single stranded labeled DNA molecules. We use the narrow-band filtering properties of a hot atom…
Molecular saturation determines distinct plasmonic enhancement scenarios for two-photon absorption signal
提出一种利用亮暗等离激元模式耦合的十字形银纳米结构，通过量子力学分析揭示分子饱和对双光子吸收信号增强机制的决定性作用，为纳米尺度光与物质相互作用控制提供新途径。
Light-sheet microscopy (LSM) is a powerful imaging technique that uses a planar illumination oriented orthogonally to the detection axis. Two-photon (2P) LSM is a variant of LSM that exploits the 2P absorption effect for sample excitation. The light polarization state plays a significant, and often overlooked, role in 2P absorption processes. The scope of this work is to test whether using different polarization states for excitation light can affect the detected signal levels in 2P LSM imaging of typical biological samples with a spatially unordered dye population. Supported by a theoretical …
Stimulated emission in small-molecule organic films at a high dye concentration is generally hindered by fluorescence quenching, especially in the red region of the spectrum. Here we demonstrate the achievement of high net gains (up to 50 cm-1) around 640 nm in thermally evaporated non-doped films of 4-di(4'-tert-butylbiphenyl-4-yl)amino-4'-dicyanovinylbenzene, which makes this material suitable for green-light pumped single-mode organic lasers with low threshold and superior stability. Lasing effect is demonstrated in a DBR resonator configuration, as well as under the form of random lasing a…
Deep mouse brain two-photon near-infrared fluorescence imaging using a superconducting nanowire single-photon detector array
本研究提出超导纳米线单光子探测器阵列用于双光子近红外荧光成像，实现小鼠脑深部超过1.1毫米的成像深度，克服散射限制，推动深层组织成像技术发展。
By circumventing the optical diffraction limit, super-resolved fluorescence microscopies enable the study of larger cellular structures and molecular assemblies. However, fluorescence nanoscopy currently lacks the spatiotemporal resolution to resolve distances on the size of individual molecules and reveal the conformational fine structure and dynamics of molecular complexes. Here we establish FRET nanoscopy by combining colocalization STED microscopy with multiparameter FRET spectroscopy. We simultaneously localize donor and acceptor dyes of single FRET pairs with nanometer resolution and qua…
扫码添加微信好友，提出您的宝贵建议 👇
💡 备注请填写：网站反馈
发表机构由 AI 从论文文本抽取，如发现错误，欢迎反馈修正建议。