Search

Is it possible to form an image using light produced by stimulated emission? Here we study light scatter off an assembly of excited chromophores. Due to the Optical Theorem, stimulated emission is necessarily accompanied by excited state Rayleigh scattering. Both processes can be used to form images, though they have different dependencies on scattering direction, wavelength and chromophore configuration. Our results suggest several new approaches to optical imaging using fluorophore excited states., 11 pages, 4 figures

Isothermal mutual diffusion coefficients (interdiffusion coefficients) were measured for K2SO4(aq) at 298.15 ± 0.005 K, at numerous concentrations ranging from dilute solutions to near saturation (0.59648 mol·dm–3; 0.61349 mol·kg–1) under free diffusion boundary conditions, using high precision Rayleigh interferometry. Under the experimental conditions these diffusion coefficients are on the volume-fixed reference frame Dv. Two series of experiments were performed, the first using the traditional experimental approach with a mercury lamp source and with the interference patterns being recorded on glass photographic plates, and the second with a He–Ne laser light source and computerized data acquisition using a photodiode array. The results from both series of experiments are in excellent agreement, and generally yield diffusion coefficients precise to at least 0.002 × 10–9 m2·s–1 (0.15% to 0.19%) and in most cases to 0.001 × 10–9 m2·s–1 (0.07% to 0.1%). These experiments also yield accurate values of the refractive index differences for the solution pairs used in the diffusion experiments. The new diffusion coefficients are compared to two sets of published values of diffusion coefficients for K2SO4(aq) which are somewhat discrepant from each other. This study extends and complements our earlier work on the diffusion coefficients of the most common brine salts: NaCl(aq), KCl(aq), MgCl2(aq), CaCl2(aq), Na2SO4(aq),]MgSO4(aq), NaHCO3(aq), and KHCO3(aq) at 298.15 K.

Accurate Rayleigh scattering and absorption cross sections of atmospheric gases are essential for understanding the propagation of electromagnetic radiation in planetary atmospheres. Accurate extinction cross sections are also essential for calibrating high-finesse optical cavities and differential optical absorption spectroscopy and for accurate remote sensing. In this study, we measured the scattering and absorption cross sections of carbon dioxide, nitrous oxide, sulfur hexafluoride, oxygen, and methane in the continuous wavelength range of 307–725 nm using broadband cavity-enhanced spectroscopy (BBCES). The experimentally derived Rayleigh scattering cross sections for CO2, N2O, SF6, O2, and CH4 agree with refractive index-based calculations, with a difference of (0.4 ± 1.2) %, (−0.6 ± 1.1) %, (0.9 ± 1.4) %, (2.8 ± 1.2) %, and (0.9 ± 2.2) %, respectively. The O2–O2 collision-induced absorption and absorption by methane are obtained with high precision at the 0.8 nm resolution of our BBCES instrument in the 307–725 nm wavelength range. New dispersion relations for N2O, SF6, and CH4 were derived using data in the UV–vis wavelength range. This study provides dispersion relations for refractive indices, n-based Rayleigh scattering cross sections, and absorption cross sections based on more continuous and more extended wavelength ranges than available in the current literature.

In pH 3.1 HCOOH-HCOONa buffer solution, liquid crystal 5CB was used as the probe to generate a strong resonance Rayleigh scattering (RRS) peak at 450 nm. Gold nanoparticles (AuNPs) could catalyse the reaction of phosphomolybdic acid (PMo)-formic acid (FA) to form phosphomolybdenum blue (PMoB), which caused the RRS strength of PMo at 450 nm to decrease linearly. Hg2+ could have an electrostatic substitution reaction with AuNPs, thereby inhibiting the catalytic effect of AuNPs, and the RRS peak was enhanced. In the range of 2.5 × 10−9 mol/L–4.5 × 10−8 mol/L Hg2+, as the concentration of Hg2+ increased, the catalytic effect of AuNPs gradually weakened, and the peak value of RRS at 450 nm (ΔI) was linearly increased. The regression equation is ΔI450nm = 27.988C−5.6159, and the detection limit is 1.0 nmol/L. The method has been used to detect Hg2+ in wastewater with satisfactory results.

This paper presents a linear dependence of temperature sensitivity in Rayleigh scattering-based optical frequency domain reflectometry (OFDR) on the concentration of germanium in the fiber core. Eight different commercially available single-mode fibers have been investigated and compared with the standard SMF-28 Corning fiber. We have experimentally analyzed the influence of germanium concentration in the fiber core, the protective coating, the degree of reduction of the fiber cladding’s diameter, and the amount of humidity on Rayleigh backscatter in response to temperatures ranging from 10-90°C. Maximum sensitivity was 1.343 GHz/°C for 20.78 mol % of the germanium-doped bare fiber and it does not depend on changes in humidity. The experimental results were compared and qualitatively agreed with the numerical simulations.

In the weakly alkaline medium, sodium carboxymethyl cellulose (NaCMC) can react with fuchsin to form a large volume ion-association complex. As a result of the reaction, intensity of resonance Rayleigh scattering (IRRS) was enhanced significantly and a new RRS spectrum appeared. Two maximum scattering peaks were located at 320 nm and 600 nm for fuchsin–NaCMC. Under optimal conditions, there is a linear relationship between the relative intensity of RRS and the concentration of NaCMC in the range of 0 ~ 10.0 mg/L. The regression equation was ΔIRRS = 43.427C − 9.5235, with a correlation coefficient of 0.9974 and a detection limit of 0.028 mg/L. Moreover, the effects of foreign substances on the determination of NaCMC were investigated. Based on this, a new method was proposed for the determination of NaCMC in dairy products. This method has been applied to the determination of NaCMC in several dairy product samples with satisfactory results, and the average recoveries were within the range of 86.9 ~ 112.6% with the RSDs below 5.7%.

Random fiber lasers (RFLs), featuring a simple open cavity but with unique lasing characteristics, have captured considerable attention in the past several decades. Particularly, RFLs assisted by the passive feedback exhibit excellent robustness and compactness owing to the combination of active amplification and passive feedback from random distributed Rayleigh scattering. However, RFLs with the aid of the passive feedback reported previously are primarily operating in the near-infrared wavelength region of 1.1 μm or 1.5 μm based on the ytterbium or erbium doped active fibers. Here, we propose and demonstrate a random fiber laser configuration combining the passive feedback from a piece of single mode fiber with the active gain based on the thulium doped fiber, and extend the operation wavelength to the critically important mid-infrared wavelength band of ∼2 μm. The spectral and temporal characteristics of the lasing output are evaluated and compared with those generated in a single pass amplification structure and a conventional resonant structure. Our results show that the passive feedback assisted RFL has a stabilized lasing wavelength and notably suppressed temporal dynamics. This work not only advances the development of RFLs, but also provides a promising strategy to achieve mid-infrared laser emission with a comparatively low relative intensity noise.

In this study, we investigated the realization of maximum tuning range of a random fibre laser by adjusting the pump wavelength and power as well as changing the lengths of single-mode and erbium-d...

Rayleigh interferometry is one of the most precise and accurate methods for the experimental determination of the mutual diffusion coefficients of both electrolytes and non-electrolytes in liquid solutions. For binary solutions at moderate and high concentrations where the concentration dependences of both diffusion coefficient and refractive index can be assumed to be linear or almost linear and the concentration difference ∆C between a pair of solutions undergoing free diffusion is not large compared to their average concentration, and by using proper combinations of the interference fringe positions as they vary with time, under these conditions diffusion coefficients are obtained that are independent of the size of ∆C. However, this situation becomes more complicated at low concentrations for electrolyte solutions where the concentration dependences of both the diffusion coefficient and refractive index are non-linear, with C1/2 dependence for the diffusion coefficient and C3/2 dependence for the refractive index. As a test of these effects on calculated mutual diffusion of electrolyte solutions at low concentrations as measured by Rayleigh interferometry, apparent mutual diffusion coefficients Dv,a (volume-fixed reference frame) were measured for fixed average concentrations C = (0.02989 ± 0.00001) mol·dm–3 of Na2SO4(aq) at 298.15 K while varying ∆C/C from 0.66673 to 2, a threefold variation. The dependence of the diffusion coefficient on ∆C/C was found to be linear, yielding Dv = 1.0416 × 10–9 m2·s–1 for an infinitely small concentration difference between the diffusing solutions.

Charged droplets have been associated with distinct chemical reactivity. It is assumed that the composition of the surface layer plays a critical role in enhancing the reaction rates in the droplets relative to their bulk solution counterparts. We use atomistic modeling to relate the localization of ions in the surface layer to their ejection propensity. We find that ion ejection takes place via a two-stage process. First, a conical protrusion emerges as a result of a global droplet deformation that is insensitive to the locations of the single ions. The ions are subsequently ejected as they enter the conical regions. The study provides mechanistic insight into the ion-evaporation mechanism, which can be used to revise the commonly used ion-evaporation models. We argue that atomistic molecular dynamics simulations of minute nanodrops do not sufficiently distinguish the ion-evaporation mechanism from a Rayleigh fission. We explain mass spectrometry data on the charge state of small globular proteins and the existence of supercharged droplet states that have been detected in experiments.

In this paper, we revisit the disorder-order transition in 1-chloro-adamantane and present new data on 1-bromo-adamantane. Rayleigh scattering and Raman-active optical lattice phonons are used to easily characterize the phase change. Unlike Cl-derivative, the Br-derivative shows a semiordered structure in the vicinity of ambient P,T conditions, which is peculiar of this compound and seems to be due to a more reduced rotational disorder of the Br-derivative with respect to the other halogen-adamantanes. The semiordered phase is briefly discussed in terms of its Rayleigh Wing and Boson peak.

Посол является традиционным и наиболее целесообразным процессом тех-нологической обработки для рыб семейства сельдевых. В рамках представленной работы исследован процесс сухого посола салаки. Определены коэффициенты диффузии соли методом фотонной корреляционной спектроскопии. При посоле применялись два вида соли: поваренная пищевая и обогащенная фитокомпонен-тами чеснока. Показано, что коэффициенты диффузии соли обогащенной на по-рядок выше, чем коэффициенты диффузии поваренной пищевой. Интенсивность диффундирующих веществ соли, обогащенной фитокомпонентами чеснока, также на протяжении всего эксперимента была выше в 1,5 раза, однако при достижении глубины 4 мм интенсивность рассеяния света у обоих образцов выравнивалась. Увеличение коэффициента диффузии говорит о том, что процесс посола интенсифицируется, так как соль, являясь носителем фитокомпонентов, проникает в ткани салаки, и, как следствие, фитокомпоненты, которыми она обогащена, также диффундируют внутрь тканей рыбы. Высокое значение интенсивности рассеяния света у образцов салаки с обогащенной солью свидетельствует о том, что более активно образуются «кластеры» соли с водой. Последнее объясняется ее влагоудерживающей способностью и подтверждает результаты проведенных ранее исследований. В данном случае можно говорить о том, что соль, обогащенная фитокомпонентами чеснока, служит комплексным барьером в технологии гидробионтов, так как обладает высоким коэффициентом диффузии, а кроме этого антимикробными и антиоксидантными свойствами, что положительно скажется на качестве готового продукта, а также его безопасности.

To effectively examine the flame propagation of premixed hydrogen-air explosion in a closed duct with obstacles, this paper conducts a numerical study of the flame propagation during the hydrogen explosion in a closed duct with obstacles. Fractal dimensions are used to represent the flame structure. When the number of obstacles is 1, 2, and 3, the fractal dimensions corresponding to flame propagation are 1.632, 1.655 and 1.661 respectively. The research shows that the propagation of explosion flame under obstacle conditions accords with typical self-similarity. The more the number of obstacles, the stronger Kelvin-Helmholtz (K–H) instability and Rayleigh -Taylor (R-T) instability formed, the more obviously the flame is stretched, and the greater the turbulence of the flame propagation. When the number of obstacles is 1, 2 and 3, the corresponding maximum speeds are 108 m/s, 176 m/s and 196 m/s respectively, and thus the flame propagation speed is proportional to the number of obstacles. Flame acceleration is caused by the flow compression due to reduced flow area at the cross-section of obstacles. The flame propagation speed manifests different characteristics through the spherical flame propagation, transformation from the finger flame to twisted flame propagation, and the twisted flame propagation, corresponding to three stages of slow growth, continuous growth and turbulent growth in explosion overpressure.

Ephedrine (EH) and pseudoephedrine (PEH), which are chiral enantiomers commonly used clinically, have different pharmacological actions and treatment effects due to their chiral nature. In the presence of Pd2+ , the reaction system of Ery B (erythrosin B)-Pd2+ has a strong resonance Rayleigh scattering (RRS) intensity. Adding EH into this system reduced the RRS intensity, but PEH could not produce this phenomenon. The chiral recognition of these enantiomers could be achieved according to this spectral difference. At the same time, reduction in RRS strength of the reaction system is proportional to the concentration of EH. Under optimized conditions, the linear range is 40-960 ng/ml, and the detection limit is 3.9 ng/ml. A new method for the rapid detection of EH enantiomers can be established. Based on this assay, a new method for the determination of the chiral enantiomers of EH and PEH can be developed.

Energy harvesting from mechanical energy around ambient by flexible nanogenerators is one of the most efficient ways to generate green and renewable energy. Lead zirconate titanate (PZT) particles were embedded into a polyvinylidene fluoride (PVDF) polymer matrix to prepare mixed 0–3 and 1–3 connectivity nanocomposite fibers by electrospinning method. Various theoretical models of Maxwell-Garnett, Rayleigh, and Tinga etc were presented at two different Classes to predict the dielectric constant of PVDF-PZT nanocomposite fibers and compared the predicted results with the experimental results. Also, the piezoelectric properties like the piezoelectric coefficient (d33) and piezoelectric voltage coefficient (g33) were predicted by the Furukawa model and the predicted values were compared with the experimental values. Finally, the experimental model was derived to predict the dielectric constant of binary composites with mixed 0–3 and 1–3 connectivity. Compared to well-known models, the proposed experimental model accurately predicted the dielectric constant of PVDF-PZT nanocomposite fibers. The highest and lowest difference between the theoretical and the experimental results were obtained 12.24% and 0.12% for PZT volume fractions 1.1 and 17, respectively. Also, due to the linear relationship between the dielectric constant and piezoelectric coefficients, this model was generalized to predict the piezoelectric coefficients.

Properties of gas clusters such as the size and number density when expanding into the vacuum after passing through a conical nozzle are analyzed for argon at an average density of 1020/cm3. Temporally and spatially resolved size and density distribution were measured from all-optical methods of Rayleigh scattering measurement and Nomarski interferometry using a CW laser. At the gas backing pressure of 80 bar, Ar clusters as large as 100 nm were obtained, which differs significantly from the size estimated by the conventional Hagena scaling law. The two independent methods of cluster characterization presented here would be useful to precisely determine the initial conditions in a variety of intense laser-cluster interaction driven applications such as neutron generation, thermonuclear fusion, efficient x-ray emission, and energetic ion acceleration.

The experimental speeds of sound combined with Brillouin frequency shifts of ethyl laurate at temperatures from 294.97 to 572.89 K along six isobaric lines from 0.1 to 10.0 MPa were measured by Ray...

This paper demonstrates a monolithic surface acoustic wave amplifier fabricated by state-of-the-art heterogenous integration of a III-V InGaAs-based epitaxial material stack and LiNbO3. We compare amplification of Raleigh-SAW and leaky-SAW modes on a on Y-cut, X-propagating delay line amplifier. Due to the superior properties of the materials employed, we observe a net terminal gain of 3dB for an LSAW overtone mode This platform enables further advances in active and non-reciprocal piezoelectric acoustic devices.

The propagation properties of surface acoustic wave (SAW) on the Na0.5Bi0.5TiO3–BaTiO3 (NBBT) substrate with different crystal cuts were theoretically analyzed by Finite Element Method (FEM). The calculated results, for the NBBT with the optimized electrode type and thickness, indicate the existence of Rayleigh and Sezawa modes with high electromechanical coupling factor K2 ~18% and ~6.8% respectively, which are considerably higher than that of the conventional lithium niobate (LiNbO3) single crystal for SAW applications. The research provides a comprehensive understanding of the SAW propagation characteristics of lead-free NBBT, and explores the promising applications of NBBT in wideband SAW devices.

A new method for determining lead by resonance Rayleigh scattering (RRS) has been proposed and its operation mechanism has been discussed. In pH 5.0 HAc–NaAc buffer solution, Pb(II) reacted with xylenol orange (XO) to form a chelating anion ([Pb (H2In)] 2–), which further reacted with crystal violet (CV) to form ternary ionic complexes, resulting in the enhancement of RRS intensity. The RRS intensity increases linearly with the concentration of Pb(II) in the range of 2.00 × 10–3–2.00 × 10–2 mg/L under optimal experimental conditions along with the detection limit of 9.2 × 10–5 mg/L. This method is a promising approach for the selective and sensitive determination of Pb(II) in tea.

Synthesis of carbon dots (CDs) from natural resources not only enables green synthesis and production of environmentally friendly materials, but also provides a cost-effective probe as a fluorescence nanosensor. The proposed sensor introduces a unique one-pot hydrothermal CDs synthesis from alfalfa leaves, which is promising for sensing hydrochlorothiazide (HCTZ) via inner filter effect (IFE) and resonance Rayleigh scattering (RRS). The as-prepared CDs had wide emission spectra, excitation-dependent emission, high solubility, high stability, and visible fluorescence light with a quantum yield of up to 11%. The absorption of HCTZ overlapped with the excitation spectra of CDs. Therefore, CDs represented excellent quenching due to IFE when HCTZ was gradually added. Furthermore, this fluorescent sensor was successfully used to quantify HCTZ in the linear ranges (0.17-2.50 μg mL-1) with the limit of detection of 0.11 μg mL-1. The sensing system was simple as no surface functionalization was required for CDs, leading to less laborious steps and more cost-effective synthesis. The reaction time was short, i.e., less than 2 min, indicating a simple approach for rapid analysis of HCTZ. By optimizing conditions, successful measurements were carried out on pharmaceutical tablets.

Spatially and temporally resolved information on thermochemical conditions in hydrocarbon/air flames requires concentration and temperature data obtained by spontaneous Raman/Rayleigh scattering. During the combustion of renewable and more complex fuels, such as ethanol, partially oxidized hydrocarbons are created as intermediates in concentrations large enough to have an influence on the turbulence-chemistry interaction. To obtain concentrations and temperature in flames at atmospheric pressure with a high spatial and temporal resolution, information on the temperature dependent shape and scattering cross section of the major as well as the minor intermediate species is required. Therefore, a novel gas heater based on mixing the hydrocarbons with helium at high temperatures in combination with a multipass Raman spectrometer were developed, able to characterize ro-vibrational Raman scattering of gaseous ethanol in the gaseous phase up to high temperatures and in different spectral regions. The setup is described, its performance evaluated and Raman spectra of gaseous ethanol at atmospheric pressure up to high temperatures is demonstrated.

Publisher Summary Structures subjected to dynamic loading, particularly aircraft, vibrate or oscillate in a frequently complex manner. An aircraft, for example, possesses an infinite number of natural or normal modes of vibration. Simplifying assumptions, such as breaking down the structure into a number of concentrated masses connected by weightless beams (lumped mass concept), are made, but whatever method is employed, the natural modes and frequencies of vibration of a structure must be known before flutter speeds and frequencies can be found. This chapter concentrates on the calculation of the normal modes and frequencies of vibration of a variety of beam and mass systems. The determination of natural frequencies and normal mode shapes for beams of non-uniform section involves the solution and fulfillment of the appropriate boundary conditions. However, with the exception of a few special cases, such solutions do not exist and the natural frequencies are obtained by approximate methods, such as the Rayleigh and Rayleigh–Ritz methods.

Different imaging solutions have been proposed over the last few decades, aimed at three-dimensional (3D) space reconstruction and obstacle detection, either based on stereo-vision principles using active pixel sensors operating in the visible part of the spectra or based on active Near Infra-Red (NIR) illumination applying the time-of-flight principle, to mention just a few. If extremely low quantum efficiencies for NIR active illumination yielded by silicon-based detector solutions are considered together with the huge photon noise levels produced by the background illumination accompanied by Rayleigh scattering effects taking place in outdoor applications, the operating limitations of these systems under harsh weather conditions, especially if relatively low-power active illumination is used, are evident. If longer wavelengths for active illumination are applied to overcome these issues, indium gallium arsenide (InGaAs)-based photodetectors become the technology of choice, and for low-cost solutions, using a single InGaAs photodetector or an InGaAs line-sensor becomes a promising choice. In this case, the principles of Single-Pixel Imaging (SPI) and compressive sensing acquire a paramount importance. Thus, in this paper, we review and compare the different SPI developments reported. We cover a variety of SPI system architectures, modulation methods, pattern generation and reconstruction algorithms, embedded system approaches, and 2D/3D image reconstruction methods. In addition, we introduce a Near Infra-Red Single-Pixel Imaging (NIR-SPI) sensor aimed at detecting static and dynamic objects under outdoor conditions for unmanned aerial vehicle applications.

Packaged photodiodes suffer from Fresnel reflection from the package window glass, especially at high angles of incidence. This has a notable impact particularly on black silicon (b-Si) photodiodes, which have extreme sensitivity. In this work, we show that by adding a simple grass-like alumina antireflection (AR) coating on the window glass, excellent omnidirectional sensitivity and high external quantum efficiency (EQE) of b-Si photodiodes can be retained. We demonstrate that EQE increases at all angles, and up to 15% absolute increases in EQE at a 70° angle of incidence compared to conventional uncoated glass. Furthermore, even at the incidence angle of 50°, the double-sided coating provides higher EQE than bare glass at normal incidence. Our results demonstrate that grass-like alumina coatings are efficient and omnidirectional AR coatings for photodiode package windows in a wide wavelength range across the visible spectrum to near-infrared radiation.

Funding Information: The authors greatly acknowledge the support of the Academy of Finland under grant No. 314487 and the Finnish Fire Protection Fund (Palosuojelurahasto). They also thank Dr. Kaoru Wakatsuki of Shinshu University for providing the experimental spectral absorption data of the fuel gases. Funding Information: The authors greatly acknowledge the support of the Academy of Finland under grant No. 314487 and the Finnish Fire Protection Fund (Palosuojelurahasto). They also thank Dr. Kaoru Wakatsuki of Shinshu University for providing the experimental spectral absorption data of the fuel gases. Publisher Copyright: © 2021 The Authors Using the high-resolution experimental spectral absorption coefficients of six fuel gases and the line by line absorption spectra of CO and CH4 based on HITRAN and HITEMP spectral databases, in this paper, novel coefficients for weighted-sum-of-gray-gases (WSGG) model are presented for Heptane, Methane, Methanol, MMA, Propane, Propylene, Toluene, and CO. Moreover, for soot, the spectral absorption coefficients were calculated assuming Rayleigh regime implementing the complex index of refraction obtained from the correlations of Chang and Charalampopoulos. The presented WSGG models were coupled with those of literature for CO2 and H2O by means of the superposition method. The models were first validated in several one-dimensional benchmarks representing various levels of inhomogeneous conditions in temperature, gas concentration and soot loading. Then, the WSGG models were employed in solving a three-dimensional case representing a Heptane pool fire. Using the time averaged 3-D CFD profiles, the WSGG models solved the spectral radiative heat transfer exhibiting excellent agreement with the results of line by line calculations in terms of radiative heat flux and radiative heat source. Moreover, the emissivity charts were provided comparing the emissivity calculated by LBL calculations with those of the new WSGG models.

In this work the first 3D Smoothed Particle Hydrodynamics model of a Rayleigh collapse for an empty cavity is proposed with the aim of improving the hydrodynamic analysis of a non-symmetrical collapse. The hydrodynamics of the model is validated against the solution of the Rayleigh-Plesset equation for a symmetrical collapse. The model is then used to simulate a non-symmetrical collapse of an empty cavity attached to a solid surface with γ=0.6 induced by an external pressure of 50 [MPa]. The results shows that is possible to identify three regions where the hydrodynamics of the collapsing cavity shows different features. For all the stages of the collapse the simulation shows smooth pressure and velocity fields in the liquid and in the solid phase with the formation of a vortex ring in the final phase of the collapse. Finally, the model is compared to a previous 2D model to highlight strong, weak points and the key differences of both approaches in final phase of the collapse.

We analyzed the higher-order mode SAW characteristics on polarity inverted ScAlN layer / high phase velocity AlN, boron nitride (BN) substrate. The $K^{1}$ and phase velocity of BN substrate structure were higher than those of AlN substrate structure. The effects of a polarity inverted two-layered ScAlN film for Rayleigh SAW (RSAW) characteristic were investigated. The maximum $K^{2}$ of 2nd mode RSAW were approximately 1.9 times in AlN substrate structure and 2.0 times in BN substrate structure higher than the $\boldsymbol{K}^{2}$ of one-layer ScAlN film/AlN or BN substrate, respectively. From the frequency characteristics of admittance on polarity inverted ScAlN film/the BN substrate structure, setting the boundary of polarity inverted structure at the position where the particle displacement was concentrated close at the film surface, was effective for the enhancement of the K2 of 2nd mode RSAW.

Using citric acid (CA) and ethylenediamine (EDA) as precursors, stable nitrogen-doped carbon dots (CD) nanosols were prepared by microwave procedure and characterized in detail. It was found that CDNs catalyze ethanol (Et)-HAuCl4 to generate gold nanoparticles (AuNPs), which have strong surface plasmon resonance, Rayleigh scattering, (RRS) and a surface plasmon resonance (SPR) absorption (Abs) effect at 370 nm and 575 nm, respectively. Compled the new catalytic amplification indicator reaction with the specific As3+ aptamer reaction, a new RRS/Abs dual-mode aptamer sensor for the assay of trace As3+ was developed, based on the RRS/Abs signals increasing linearly with As3+ increasing in the ranges of 5–250 nmol/L and 50−250 nmol/L, whose detection limits were 0.8 nmol/L and 3.4 nmol/L As3+, respectively. This analytical method has the advantages of high selectivity, simplicity, and rapidity, and it has been successfully applied to the detection of practical samples.

Duloxetine is an antidepressant that exhibits its action by preventing the reuptake of serotonin and norepinephrine by neurons. In this analytical study, we developed two facile, sensitive methods for duloxetine analysis. Both methods rely on the formation of binary association complex between erythrosine-B and duloxetine in an acidic medium using spectrofluorimetric and resonance Rayleigh scattering (RRS) techniques. Spectrofluorimetric method simply uses the quenching property of the formed complex on the native fluorescence of erythrosine-B at an emission wavelength of 557.2 nm ( λ ex = 528.6), while RRS is based on detecting the enhancement in the RRS signal at 357.2 nm. The proposed methods have been validated according to the International Conference on Harmonization guidelines. The approaches provide linear assay of duloxetine hydrochloride over 0.1–2.4 µg ml −1 and 0.2–2.0 µg ml −1 for spectrofluorimetric and RRS methods, respectively. Variables affecting methods and complex formation were studied and optimized. The limit of detection values were 0.03 and 0.056 µg ml −1 for spectrofluorimetric and RRS methods, respectively. Both approaches were applied with acceptable results for formulation analysis and evaluation of cymbatex capsule content uniformity.

The problems of the appearance of laser-induced filamets in the matter are discussed. A detailed analysis of the formation of such structures in various media: from air to silicon carbide, is represented. The influence of the spectral composition, the number of pulses and the duration of the irradiation and the medium on the geometric dimensions of the resulting structures and on their phase states is shown. In this case, the sizes of filaments vary from several hundred nanometers for silicon carbide to several hundred meters for air. The emission spectrum is continuous, and resembles the Cherenkov radiation. Therefore, the idea was developed that the radiation of filaments and the radiation of Cherenkov are of the same nature. The problems of the mechanisms of the formation of laser-induced destruction cascades in silicon carbide are discussed. To explain the experimental results, we used modified Rayleigh models (diffraction stratification of the laser beam and critical sizes of nanovoids), physicochemical models for determining critical energy values for the corresponding processes, and models for optically-induced Cherenkov radiation.

This work describes an incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for quantification of HONO and NO2 mixing ratios in ambient air. The instrument is operated in the near-ultraviolet spectral region between 361 and 388 nm. The mirror reflectivity and optical cavity transmission function were determined from the optical extinction observed when sampling air and helium. To verify the accuracy of this approach, Rayleigh scattering cross sections of nitrogen and argon were measured and found to be in quantitative agreement with literature values. The mirror reflectivity exceeded 99.98 %, at its maximum near 373 nm, resulting in an absorption path length of 6 km from a 1 m long optical cavity. The instrument precision was assessed through Allan variance analyses and showed minimum deviations of ±58 and ±210 pptv (1σ) for HONO and NO2, respectively, at an optimum acquisition time of 5 min. Measurements of HONO and NO2 mixing ratios in laboratory-generated mixtures by IBBCEAS were compared to thermal dissociation cavity ring-down spectroscopy (TD-CRDS) data and agreed within combined experimental uncertainties. Sample ambient air data collected in Calgary are presented.

Owing to their wide direct bandgap tunability, III-nitride (III-N) compound semiconductors have been proven instrumental in the development of blue light-emitting diodes that led to the so-called solid-state lighting revolution and blue laser diodes that are used for optical data storage. Beyond such conventional optoelectronic devices, in this review, we explore the progress made in the past 15 years with this low refractive index material family for the realization of microdisks as well as 2D and 1D photonic crystal (PhC) membrane cavities. Critical aspects related to their design and fabrication are first highlighted. Then, the optical properties of passive PhC structures designed for near-infrared such as their quality factor and their mode volume are addressed. Additional challenges dealing with fabrication pertaining to structures designed for shorter wavelengths, namely the visible to ultraviolet spectral range, are also critically reviewed and analyzed. Various applications ranging from second and third harmonic generation to microlasers and nanolasers are then discussed. Finally, forthcoming challenges and novel fields of application of III-N photonic cavities are commented.

It remains a problem for direct detection of small inorganic nitrite ions using resonance Rayleigh scattering (RRS) method based on the direct dye-binding reaction. In the present study, a redox-derivatization reaction taking only 5 min was introduced prior to nitrite detection. In the redox-derivatization reaction, nitrite ions were reduced by excess iodine ions to generate triiodide ions (I3−), which were further derivatized with a cationic dye (basic violet 1, BV1) to form the ion associates of I3−-BV1. Therefore, the RRS signal was significantly enhanced, resulting from the increase of particle size and resonance-enhanced scattering effect. The analytical procedure was performed by just mixing nitrite, oxidant, acid, and dye all-in-one, avoiding the tediousness of a multi-step process or the preparation of nanoparticles. The whole detection process including the redox-derivatization reaction was less than 6 min. The reaction conditions such as concentration of hydrochloric acid, potassium iodide, and BV1, reaction time, and temperature were investigated. Under optimum conditions, the concentration of nitrite was linear with an RRS signal of I3−-BV1 ion associates at 320 nm in the range of 0.015–1.2 mg/L. The limit of detection (LOD) was calculated to be 3.0 μg/L. The RRS method was applied to the determination of nitrite in real samples such as pork sausage, milk powder, and water with recovery of 95.2–112%. With advantages of rapidness, high sensitivity, and high selectivity, the method indicates potential applicability for detection of nitrite in complex samples. The method also provides an instructive protocol for detection of analytes that generate no/weak RRS enhancement after the direct dye-binding reaction.

For the first time, a highly sensitive and selective detection technology of high-performance liquid chromatography associated with resonance Rayleigh scattering spectra (HPLC-RRS) is applied to analyze migraine drugs including zolmitriptan (ZON) and rizatriptan (RIN). In an HAc–NaAc buffer solution (pH = 4.5), ZON and palladium(II) chelate to form a chelating cation, namely, [Pd·ZON]2+, and then react with Erythrosin B (Ery) via electrostatic attractions and hydrophobicity to form a ternary complex, [Pd·ZON]·Ery2, resulting in a significantly enhanced RRS signal. The RRS signal was detected at the synchronous model. The calibration curves of ZON and RIN were linear in the range from 0.027 to 25 μg mL−1, and the detection limits (S/N = 3) were 9.70 ng mL−1 and 4.76 ng mL−1, respectively. In addition, the HPLC-RRS method showed that the recovery of the two migraine drugs was 98.90% to 100.87% and the RSD (n = 6) was 1.67% to 4.86%. In this study, the experiment conditions were optimized, and the reaction mechanism and reason for increment in RRS were studied. In human urine samples, the established method was applied for the synchronous detection of two antimigraine drugs with satisfactory results.

Multimode sensing has attracted extensive attention because they provide more than one transduction channel, thus improving accuracy and sensitivity. Due to the structural diversity, MnO2 nanosheets and nanoneedles were successively obtained via one-step redox reaction and different self-assembly methods. MnO2 nanosheets possess outstanding optical properties including extremely strong resonance Rayleigh scattering (RRS) and absorbance signal, and were selected as a dual-mode sensing material. Inspired by the selectivity of alkaline phosphatase (ALP) towards dephosphorylate ascorbic acid 2-phosphate (AAP) to generate ascorbic acid (AA), which has the ability to decompose MnO2 nanosheets along with optical signals and colour change, a dual-mode optical ALP sensing platform has been designed. Therefore, MnO2 nanosheets can serve as colorimetric probes by directly visualizing the colour variation with bare eyes. Moreover, the detection limit obtained by the RRS sensing mode can be as low as 0.17 mU L−1, which is far superior to that obtained by previously reported methods. The strategy not only has good feasibility and sensitivity, but also shows good prospects for a series of ALP-extended sensing applications.

The core-shell kinds of nanoparticles are greatly useful in biomedical applications inclined to targeted drug delivery, sensing, etc. The electromagnetic interaction characteristics of silicon dioxide (SiO2)-vanadium dioxide (VO2) core-shell nanoparticle of deep subwavelength size are discussed. The assumptions allow the use of Rayleigh scattering theory for analytical approach. Because of VO2 having inherent temperature-dependent constitutive characteristics, the light-matter interaction properties are taken into account in terms of normalized polarizability, scattering- and absorption cross-sections, considering the different values of size parameters as well as ambient temperature. It is found that the dimensional properties of chosen nanoparticles can be exploited to tune the spectral features, and also, the usefulness of these becomes obvious in temperature sensing. Moreover, the effect of interchanging the core/shell mediums (of the nanoparticles) on the scattering and absorption characteristics are also obtained. The results reveal the loss of resonance in this case.

In this work, a resonance Rayleigh scattering technique and a spectrofluorimetric technique were applied to the quantification of cyclobenzaprine through two validated methods. The suggested methods are based on a facile association complex formation between cyclobenzaprine and eosin Y reagent in the acidic medium. The resonance Rayleigh scattering method relied on the enhancement in the resonance Rayleigh scattering spectrum of eosin Y at 370 nm after the addition of cyclobenzaprine. On the other hand, the spectrofluorimetric quantification relied on the quenching effect of cyclobenzaprine on the fluorescence strength of the eosin Y reagent at 545 nm (excitation wavelength at 300 nm). The suggested methods were linear over the ranges of 0.07–1.75 μg/mL and 0.15–2.0 μg/mL with detection limit values of 0.023 μg/mL and 0.048 μg/mL for the resonance Rayleigh scattering method and the spectrofluorimetric method, respectively. All reaction conditions for cyclobenzaprine–eosin Y formation were experimentally evaluated and optimized. In addition, both methods were validated based on ICH rules. Furthermore, the developed methods were practically applied to the analysis of cyclobenzaprine in its commercial tablet dosage form with acceptable recoveries. Moreover, the content uniformity test of the commercial cyclobenzaprine tablets was successfully applied using the proposed spectroscopic methods based on USP rules.