Emission Kinetics Research Articles

Defect profiling in FEFET Si:HfO2 layers

Ferroelectric Si-doped HfO2 is a promising candidate for future generation memory devices. However, such devices are vulnerable to significant threshold voltage shifts resulting from charge trapping in oxide defects. We use complementary characterization and modeling techniques to reveal significant electron trapping/de-trapping behavior, together with a strong temperature dependence of the electron emission kinetics in ferroelectric layers, which results from the onset of polarization of the ferroelectric layer. This can lead to an apparent difference in the defect characteristics in ferroelectric-HfO2 compared to the paraelectric-HfO2 structures they are shown to closely resemble when this contribution is decoupled. The results demonstrate the presence of a defect band closely aligned to the silicon conduction band, which can easily be accessed during device operation.

Indoor use of essential oil-based cleaning products: Emission rate and indoor air quality impact assessment based on a realistic application methodology

Cleaning is performed to increase hygiene, esthetics and material preservation. Despite its benefits, cleaning also poses risks, potentially contributing to nearly 20% of indoor pollution. As indoor air quality has become a major human health concern, “natural-scented” cleaning products, formulated with essential oils, have become market leaders among household products. However, these consumer products have benefitted from skillful marketing strategies based on the ambiguity of the words “green” and “natural”. The characterization of the emission processes studied through 1-m3 chamber experiments under a realistic scenario suggests variable maximum total terpene concentrations from 150 to 300 ppb. The estimated emission rate profiles confirm that the liquid-to-gas transfer of terpenes is driven by (i) the formulation of the product matrix inducing specific chemical affinities, (ii) the liquid content of individual terpenes, and (iii) the intrinsic volatility of terpenes. A unique formaldehyde emission kinetics profile was observed, suggesting the presence of a unique emission source: formaldehyde-releasers. Consequently, the use of essential-oil-based cleaning products might generate a long-term increase in the indoor formaldehyde concentration, and the maximum levels might be sustained for several hours after cleaning. Thus, essential-oil-based cleaners should be seriously considered as versatile and significant sources of fragrance molecules and formaldehyde.

Effect of Random Nanostructured Metallic Environments on Spontaneous Emission of HITC Dye.

We have studied emission kinetics of HITC laser dye on top of glass, smooth Au films, and randomly structured porous Au nanofoams. The observed concentration quenching of luminescence of highly concentrated dye on top of glass (energy transfer to acceptors) and the inhibition of the concentration quenching in vicinity of smooth Au films were in accord with our recent findings. Intriguingly, the emission kinetics recorded in different local spots of the Au nanofoam samples had a spread of the decay rates, which was large at low dye concentrations and became narrower with increase of the dye concentration. We infer that in different subvolumes of Au nanofoams, HITC molecules are coupled to the nanofoams weaker or stronger. The inhibition of the concentration quenching in Au nanofoams was stronger than on top of smooth Au films. This was true for all weakly and strongly coupled subvolumes contributing to the spread of the emission kinetics. The experimental observations were explained using theoretical model accounting for change in the Förster radius caused by the strong energy transfer to metal.

Multi-strain volatile profiling of pathogenic and commensal cutaneous bacteria

The detection of volatile organic compounds (VOC) emitted by pathogenic bacteria has been proposed as a potential non-invasive approach for characterising various infectious diseases as well as wound infections. Studying microbial VOC profiles in vitro allows the mechanisms governing VOC production and the cellular origin of VOCs to be deduced. However, inter-study comparisons of microbial VOC data remains a challenge due to the variation in instrumental and growth parameters across studies. In this work, multiple strains of pathogenic and commensal cutaneous bacteria were analysed using headspace solid phase micro-extraction coupled with gas chromatography–mass spectrometry. A kinetic study was also carried out to assess the relationship between bacterial VOC profiles and the growth phase of cells. Comprehensive bacterial VOC profiles were successfully discriminated at the species-level, while strain-level variation was only observed in specific species and to a small degree. Temporal emission kinetics showed that the emission of particular compound groups were proportional to the respective growth phase for individual S. aureus and P. aeruginosa samples. Standardised experimental workflows are needed to improve comparability across studies and ultimately elevate the field of microbial VOC profiling. Our results build on and support previous literature and demonstrate that comprehensive discriminative results can be achieved using simple experimental and data analysis workflows.

Dynamics of aerosol generation and release – Dry powder inhaler performance considerations

The main objective of the work was to investigate how the dynamics of inhalation affect aerosol release process in real-time, with an unsteady airflow through passive dry powder inhalers (DPIs) of comparable airflow resistance, but different principle of powder release. It consists of two complementary studies, concerning dynamics of controlled aerosol release (emission kinetics) and dynamics of aerosol generation (aerosol size characteristics in time series).Aerosol behavior of the powder was studied experimentally at the outlet of the inhalers: RS01 inhaler (Plastiape Spa, Osnago LC, Lombardy, Italy) and Turbospin (Ph&T, Milano, Lombardy, Italy). Two breathing profiles were analyzed throughout the study. Timing of aerosol emission was done by light scattering. Aerosol characterization was done by laser diffraction. It resulted in time evolution of volume concentration and volumetric particle size distribution.Both the design of the passive DPI inhaler and the dynamics of the inhalation (along with its intensification) influence the course of the aerosol generation and emission. The process of aerosol emission occurs only in the initial part of the inhalation process, before the peak inspiratory flow rate is established. This part is strongly responsible for the quality of the aerosol emitted from the device and consequently will potentially influence the drug delivery.

Facile access to photo-switchable, dynamic-optical, multi-colored and solid-state materials from carbon dots and cellulose for photo-rewritable paper and advanced anti-counterfeiting

Dynamic optical materials can respond to external stimuli to give intriguing and chameleon-like visual effect and carry more information, they hence have attracted considerable attention. In this work, we propose a simple and efficient strategy to construct multi-color solid-state carbon dots (CDs) materials with photo-switchable and reversible dynamic-optical properties. A photochromic and positively-charged cellulose derivative C-Im+-SP with an imidazole salt (Im+) group and a spiropyran (SP) group is designed and synthesized. Subsequently, C-Im+-SP is spontaneously coated on the surface of negatively-charged CDs (NCDs) via electrostatic attraction to form a physical protective shell, which not only inhibits aggregation-caused quenching (ACQ) in NCDs but also promotes effective fluorescence resonance energy transfer (FRET). The resultant NCDs@C-Im+-SP exhibits a photo-triggering reversible dynamic-optical property. The NCDs to C-Im+-SP ratio can be used to effectively regulate fluorescence emission and fluorescence kinetics. The polymeric C-Im+-SP shell layer endows NCDs with excellent processability and formability, whereby NCDs@C-Im+-SP materials can be utilized as functional coatings and inks to fabricate photo-rewritable paper and dynamic anti-counterfeit patterns that have considerable potential applications for special coatings, complex anti-counterfeiting, and information encryption.

Electrical defects in m-MTDATA studied using charge transient spectroscopy

Organic electronics is an emerging technology which has received great attention in past decades due to their potential applications in the next generation electronic devices such as Organic Solar Cells, Thin Film Transistors, Organic Light Emitting Diodes. These devices are made using cost-effective materials, suitable for the low temperature processing, compatible with sustainable and easily scalable processing techniques. Degradation being the major issue, specifically roles of traps in such devices is being studied extensively to enhance the performance. In this study, charge transient spectroscopy is utilized to investigate the trap states in the prototypical small molecule 4, 4′, 4″-tris(N-3-methylphenyl-N-phenyl-amino) triphenyl-amine (m-MTDATA) based organic diodes. The trap levels have been resolved using the emission kinetics with time resolved spectroscopic analysis technique on charge transients. Varied pulses with different bias and time was applied across device to study the carrier capture kinetics. Temperature dependent measurements were also performed to isolate the trap levels. We found that initial peak is due to displacement current of the device which is related to the transport mechanism of the device. We show that the amplitude of signal is dependent on the amount of charge injected which depends on the combination of time and the bias applied. Various observed trap levels are identified based on the emission time constants but their contribution in the emission kinetics is insignificant, indicating that the amount of trap levels are very small. Charge redistribution in the trap levels was observed at higher charging time.

The Impact of Surficial Biochar Treatment on Acute H2S Emissions during Swine Manure Agitation before Pump-Out: Proof-of-the-Concept

Acute releases of hydrogen sulfide (H2S) are of serious concern in agriculture, especially when farmers agitate manure to empty storage pits before land application. Agitation can cause the release of dangerously high H2S concentrations, resulting in human and animal fatalities. To date, there is no proven technology to mitigate these short-term releases of toxic gas from manure. In our previous research, we have shown that biochar, a highly porous carbonaceous material, can float on manure and mitigate gaseous emissions over extended periods (days–weeks). In this research, we aim to test the hypothesis that biochar can mitigate H2S emissions over short periods (minutes–hours) during and shortly after manure agitation. The objective was to conduct proof-of-the-concept experiments simulating the treatment of agitated manure. Two biochars, highly alkaline and porous (HAP, pH 9.2) made from corn stover and red oak (RO, pH 7.5), were tested. Three scenarios (setups): Control (no biochar), 6 mm, and 12 mm thick layers of biochar were surficially-applied to the manure. Each setup experienced 3 min of manure agitation. Real-time concentrations of H2S were measured immediately before, during, and after agitation until the concentration returned to the initial state. The results were compared with those of the Control using the following three metrics: (1) the maximum (peak) flux, (2) total emission from the start of agitation until the concentration stabilized, and (3) the total emission during the 3 min of agitation. The Gompertz’s model for determination of the cumulative H2S emission kinetics was developed. Here, 12 mm HAP biochar treatment reduced the peak (1) by 42.5% (p = 0.125), reduced overall total emission (2) by 17.9% (p = 0.290), and significantly reduced the total emission during 3 min agitation (3) by 70.4%. Further, 6 mm HAP treatment reduced the peak (1) by 60.6%, and significantly reduced overall (2) and 3 min agitation’s (3) total emission by 64.4% and 66.6%, respectively. Moreover, 12 mm RO biochar treatment reduced the peak (1) by 23.6%, and significantly reduced overall (2) and 3 min total (3) emission by 39.3% and 62.4%, respectively. Finally, 6 mm RO treatment significantly reduced the peak (1) by 63%, overall total emission (2) by 84.7%, and total emission during 3 min agitation (3) by 67.4%. Biochar treatments have the potential to reduce the risk of inhalation exposure to H2S. Both 6 and 12 mm biochar treatments reduced the peak H2S concentrations below the General Industrial Peak Limit (OSHA PEL, 50 ppm). The 6 mm biochar treatments reduced the H2S concentrations below the General Industry Ceiling Limit (OSHA PEL, 20 ppm). Research scaling up to larger manure volumes and longer agitation is warranted.

Time-resolved luminescence of YAG:Ce and YAGG:Ce ceramics prepared by electron beam assisted synthesis

The luminescence characteristics of YAG:Ce and YAGG:Ce ceramic phosphors produced by electron beam assisted synthesis have been investigated. The obtained emission and decay kinetics characteristics have been compared with those for commercial phosphors synthesized by conventional methods and showed good qualitative and quantitative correspondence. In our opinion, the used electron-beam-assisted synthesis method could be considered as a perspective production method of high refractory multicomponent oxide ceramics.

Double- and Triple-Crystal X-Ray Diffraction Analysis of Face-Grown Gd3Ga3Al2O12:Ce Crystals

Crystals of gadolinium–gallium–aluminum garnet doped with cerium ions (Gd3Ga3Al2O12:Ce) are analyzed by X-ray diffractometry and X-ray topography. These crystals have a number of unique scintillation characteristics (including a high specific light yield, fast emission kinetics, and high energy and time resolutions), which make them promising for designing detectors of ionizing radiation in a wide energy range. It is shown that the methods used make it possible to carry out the further optimization of preparation processes of bulk crystals by revealing specific features of their growth (e.g., facet inhomogeneity, which is characteristic of Czochralski-grown single crystals).

The influence of Ce3+ codoping and excitation scheme on spectroscopic properties of NaYF4:Yb3+,Ho3+

The possibility to design and intentionally tune the luminescent properties of phosphors, e.g. their emission colour, quantum yield and kinetic behavior, is of fundamental significance and a challenge for numerous applications. Usually, to obtain multicolour emission, multiple nanomaterials with different co-dopants combinations, sizes or chemical architectures are synthesized and characterized. Of special interest would be those materials, where on-demand and in-situ modifications of multicolour emission can be obtained by changing the external stimulus, such as magnetic field, temperature, excitation intensity or pulse width. Here we synthesize and evaluate luminescent NaYF4 nanoparticles doped Yb3+/Ho3+, whose red and green emission colour is modulated by variable concentration of Ce3+ admixture, excitation pulse duration and temperature. In the first scenario (Yb3+/Ho3+ only doping), such materials exhibit strong and stable green upconversion emission. Upon Ce3+ co-doping, the red to green ratio (RGR) changed from 0,43 (for pristine dopants) to 4,23 (for 15%Ce3+ co-doped samples). Moreover, the measurement performed with excitation pulse width modulation (PWM) enabled to increase contribution of red emission in-situ. For short excitation pulses, the green emission was observed, while for longer pulses the red emission started to dominate. Finally, the energy transfer in this tri-doped system demonstrated to be susceptible to external temperature as well, with relative thermal sensitivity of 0,8%/K in biological range for 5%Ce3+ doped sample. Detailed spectroscopic analysis including temperature dependent emission spectra, rise times and emission kinetics allow us to understand and propose the possible energy transfer mechanisms in this system.

Detection by fluorescence microscopy of N-aminopeptidases in bacteria using an ICT sensor with multiphoton excitation: Usefulness for super-resolution microscopy

Bacterial proteases are relevant in pathological processes such as the survival, growth and development of microorganisms. In particular alanine amino peptidase (pepN), which is present in Gram (−) bacteria, is the only peptidase responsible for the ATP-independent degradation of cytosolic proteins in E. coli. These peptidases, including pepN, might be useful targets to fight bacterial infections, which are difficult to treat due to the increase in antibiotic resistance, as well as for diagnosis. In this work, we propose a new methodology for the identification of pepN-expressing bacteria by using a specific substrate, namely, DCM−NH−Ala. Substrate hydrolysis by pepN produces a sharp increase in the fluorescence band with peak at 662 nm when excited by a single photon at 480 nm or by two NIR photons (at approximately 800 nm). The emission kinetics are dependent on the intracellular pepN concentrations, which provide a powerful tool for detecting diverse virulent bacteria in a few minutes and with the inherent advantages of two-photon excitation. We resolved the enzymatic kinetics, obtained the Michaelis-Menten parameters (e.g., KM, vmax, and kcatalytic) and studied the photophysics of the released fluorophore DCM–NH2. In addition, DCM–NH2 meets the requirements for use in super-resolution microscopy. In bacteria with high pepN activity, the probe quickly initiates an enzymatic reaction at specific sites located on the bacterial membrane and some structures inside the bacterial body.

Fingerprinting of volatile organic compounds for quick assessment of vigour status of seeds

AbstractSeed is a fertilized mature ovule, which possesses an embryonic plant. When the dry, mature seeds are subjected to imbibition, they release a wide range of organic substances, which include low molecular weight carbonyl compounds (gases and volatiles) and water-soluble organic substances (enzymes and polysaccharides). The volatile organic compounds (VOCs) are molecules of low molecular weight (300 g mol−1) and high vapour pressure (0.01 kPa at 20°C) and include diverse chemical compounds. The nature and emission kinetics of volatiles produced from seeds vary, depending on the moisture content of the seeds. Orthodox seeds stored at ‘low seed moisture content’ undergo seed deterioration, predominantly due to lipid peroxidation, initiated by autoxidation or enzymatic oxidation of unsaturated or polyunsaturated fatty acids. This peroxidation leads to emission of volatile compounds. The quantity of VOCs emitted is positively correlated with the advancement of seed deterioration. With respect to the seed germination process, exposure of seeds to ‘high moisture conditions’ leads to increased respiration, triggers glycolysis and mobilization of storage reserves, resulting in the emission of volatile metabolic products. The quantity of VOCs emitted on commencement of metabolic activity in germinating seeds depends on (1) vigour status and (2) amount of storage reserves. Since it has been established that there is a significant difference between high and low vigour seeds with respect to quantity and profile of VOCs emitted, there is great potential for utilizing the VOC profile to obtain a quick and reproducible test of vigour status of crop seeds. In order to harness the VOC profile for quick assessment of vigour status of seeds, research has to be taken up to develop standard protocols for fingerprinting of VOCs for the purpose of seed vigour assessment and to fix the standard volatile biomarker(s) specific to crop and vigour status of seeds.

Highly stable green and red up-conversion of LiYF4:Yb3+,Ho3+ for potential application in fluorescent labeling

The development of novel phosphors with stable and efficient green and red up-conversion (UC) emission is important for many applications such as fluorescent labeling, color display and anticounterfeiting. In this work, we report a stable and efficient green and red up-converter of LiYF4:Yb3+,Ho3+ octahedrons obtained by modified hydrothermal method. The UC emission and luminescence decays of LiYF4:Yb3+,Ho3+ with various Yb3+ and Ho3+ ion concentrations were studied systematically under 976 nm LD excitation. The Yb3+ and Ho3+ ion concentrations were optimized to be 20 mol% and 1 mol% respectively, for efficient green and red UC emissions. LiYF4:Yb3+,Ho3+ presents not only controlled morphology of monodisperse octahedrons with length of ∼20 μm and width of ∼10 μm, but also performs efficient green and red UC emissions, which is about four times stronger than that of β-NaGdF4: 20 Yb3+,0.5Ho3+ (NaGdF4: 20 Yb3+,0.5Ho3+). More importantly, the stable UC emission with variation of green intensity ratio ΔG% (G% = I520-570nm/I500-700nm, ΔG%= (G%)max-(G%)min) and red intensity ratio ΔR% (R% = I625-685nm/I500-700nm, ΔR%= (R%)max-(R%)min) < 1% was found over 976 nm LD excitation power density (PD) ranging from 1.0 to 5.6 W/cm2. Whereas, their variations of ∼6% and 25% are observed at the same excitation PD for NaGdF4:20 Yb3+,0.5Ho3+ and commercial β-NaYF4:20 Yb3+,2Er3+ (NaYF4: 20 Yb3+,2Er3+), respectively. The mechanism of green and red UC emissions in LiYF4: Yb3+,Ho3+ as a consequence of energy transfer processes has been briefly discussed taking into account the UC emission kinetics. The highly stable intensity ratio of G% and R% combined with the efficient green UC color hints the potential application of LiYF4: Yb3+,Ho3+ in fluorescent labeling and color display.

Carbene–Metal–Amide Polycrystalline Materials Feature Blue Shifted Energy yet Unchanged Kinetics of Emission

The nature of carbene–metal–amide (CMA) photoluminescence in the solid state is explored through spectroscopic and quantum-chemical investigations on a representative Au-centered molecule. The crys...

Efeito de subdoses de 2,4-D sal colina na eficiência quântica do fotossistema II do algodoeiro

Deleterious effects of herbicides on the photochemical apparatus of plants can be quantified by studying the quantum yield potential of photosystem II (Fv/Fm). Therefore, the objective of this work was to evaluate the effect of subdoses of the herbicide 2,4-D choline salt formulation on the quantum efficiency of the photosystem II of cotton plantsat different phenological stages. The study adopted a completely randomized experimental design with seven replications, and the treatments consisted of nine fractions of the average rate indicated on the 2,4-D choline salt herbicide label: 0 (control); 0.4275; 0.855; 1.71; 3.42; 8.55; 17.1; 34.2 and 68.4 g ae ha-1applied at phenological stages V4 or B4 of cotton plants. The plants were evaluated for the visual symptoms of injury and the emission kinetics of maximum chlorophyll a (Fv/Fm) fluorescence at 3, 7 and 14 days after application (DAA) of the herbicide. The values obtained were analyzed by the F test and the effects of the treatments were compared by the Scott-Knott test at 5% probability. The data obtained from visual injury and Fv/Fmwere also submitted to Pearson's correlation. The correlation between visual injury and Fv/Fmin the V4 and B4 stages is negative and significant for both years of conducting the experiment. The Fv/Fmvariable was not affected by the application of subdoses lower than 3.42 g aeha-1of 2,4-D saline choline in the V4 stage and below 1.71 g aeha-1in the B4 stage of the cotton plant.

A Novel Regularized Approach for Functional Data Clustering: An Application to Milking Kinetics in Dairy Goats

Summary Motivated by an application to the clustering of milking kinetics of dairy goats, we propose a novel approach for functional data clustering. This issue is of growing interest in precision livestock farming, which is largely based on the development of data acquisition automation and on the development of interpretative tools to capitalize on high throughput raw data and to generate benchmarks for phenotypic traits. The method that we propose in the paper falls in this context. Our methodology relies on a piecewise linear estimation of curves based on a novel regularized change-point-estimation method and on the k-means algorithm applied to a vector of coefficients summarizing the curves. The statistical performance of our method is assessed through numerical experiments and is thoroughly compared with existing experiments. Our technique is finally applied to milk emission kinetics data with the aim of a better characterization of interanimal variability and towards a better understanding of the lactation process.

Structural and photoluminescent investigations of SrAl2O4:Eu[formula omitted],RE[formula omitted] improved nanophosphors for solar cells

The long afterglow green emitting materials were prepared by fast gel-combustion procedure (600 °C) using urea as fuel. This paper reports the improvement in photoluminescence intensity and persistency of Eu2+ incorporated long-persistent SrAl2O4 nanophosphors by the addition of rare earth ions (Dy3+, Pr3+, Y3+) as codopants. The materials were investigated using X-ray diffraction (XRD), Fourier transformation infrared (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. X-ray diffraction analysis exhibited the formation of pure SrAl2O4 phase with monoclinic crystal system and space group P21. FTIR spectra were used to determine the stretching and bending modes of vibrations to confirm the formation of metal–oxygen bonds. The microstructures were observed using SEM and TEM analysis. For the synthesized strontium aluminate phosphors, the photoluminescence characteristics including excitation, emission and decay kinetics were also examined. PL emission spectra, recorded at the excitation wavelength of 362 nm, exhibited the characteristics peak at 510 nm corresponding to the parity allowed 5d–4f electronic transition of Eu2+ ions. The phosphorescence intensity of the materials were greatly enhanced on addition of codopants (Dy3+, Pr3+, Y3+), without any change in the position of the peak in spectra. The outcomes of these investigations made the focused materials worthy for the applications in the solar cells and lighting technology.

Bimodal stringence-mediated response of metal-detecting luminescent whole cell bioreporters: Experimental evidence and quantitative theory

Whole cell luminescent bacterial sensors are used to monitor the bioavailability and toxicity of metals in aquatic media. Any rationale of the time response of such metal-detecting biosensors necessarily asks for the so-far missing measurement and modeling of the impacts of medium nutritional quality on lux-reporter expression and bioluminescence production. In this work, improvement of nutritional conditions in bioluminescence assays by increasing amino acid concentration is shown to generate a transition from metal concentration-dependent monomodal to bimodal bell-shaped signal. The long-term component of the latter features a stringence-mediated adaptation of the cells to deficiency in nutrients supply from the medium. The demonstration is based on the analysis of the ∼17 h response of bioluminescent Escherichia coli engineered with luxCDABE reporter genes placed under the transcriptional control of a cadmium (0−22 nM bulk solution concentration) inductible-PzntA promoter or of the ribosomal RNA rrnB P1 promoter repressed by (p)ppGpp alarmones synthesized by cells in nutritional stress. The time-dependence of normalized PzntA-luxCDABE biosensor signal is successfully reproduced by our recent theory elaborated for the kinetics of bioluminescence emission by metal-responsive biosensors. The formalism allows assessment of luciferase half-life and of the time variations of cells photoactivity with medium composition. The theoretically-determined long-term kinetics of cell photoactivation is remarkably supported by independent measurements on the rrnB P1-luxCDABE bioreporter. Results clarify the origin of the mismatch between maxima in photoactive biomass and in bioluminescence over time, and they offer practical options for addressing contaminant toxicity via cell photoactivity derived from deconvolution of normalized biosensor response.

Er3+-to-dye energy transfer in DNA-coated core and core/shell/shell upconverting nanoparticles with 980 nm and 808 nm excitation of Yb3+ and Nd3.

The capability of upconverting nanoparticles (UCNPs) to convert near infrared (NIR) into visible light has become an important feature for biosensing, imaging, therapy, and their combination. While significant achievements have been accomplished during the last decade developing nanohybrids based on UCNPs as energy donors in Förster resonance energy transfer (FRET) systems, it is still challenging to understand and control FRET from UCNPs to dyes and to adapt the NIR excitation wavelength. Here, we describe the synthesis, characterization, and steady-state and time-resolved FRET analysis of UCNP-DNA nanohybrids, in which dye labelled single stranded (ss)DNA was attached to Yb-Er-co-doped core UCNPs (c-UCNPs) and c-UCNPs with a thin Nd-doped shell and a second thin undoped shell (css-UCNPs). Despite differences in sizes, compositions, donor-acceptor distances, brightness, and excitation wavelength (980 nm for Yb3+ and 808 nm for Nd3+), all UCNP-DNA nanohybrids showed very similar concentration dependent FRET-quenching of UCNP luminescence with efficiencies between 0 and ∼20%. We analyzed luminescence intensities, decay times, and rise times and could show the entanglement of excitation and emission kinetics by simply changing the excitation wavelength from 980 nm to 808 nm for the same css-UCNPs. Time-gated FRET-sensitized dye luminescence showed dye-ssDNA concentration dependence over four orders of magnitude (1 nM to 10 μM), which suggested a possible application to nucleic acid biosensing for both 808 and 980 nm excitation.