The interaction of localized light with matter generates optical electrostriction within dielectric fluids, leading to a discernible change in the refractive index of the medium according to the ...excitation's light profile. This optical force holds critical significance in optical manipulation and plays a fundamental role in numerous photonic applications. In this study, we demonstrate the applicability of the pump-probe, photo-induced lensing (PIL) method to investigate optical electrostriction in various dielectric liquids. Notably, the thermal and nonlinear effects are observed to be temporally decoupled from the electrostriction effects, facilitating isolated observation of the latter. Our findings provide a comprehensive explanation of optical forces in the context of the recently introduced microscopic Ampère electromagnetic formalism, which is grounded in the dipolar approximation of electromagnetic sources within matter and characterizes electrostriction as an electromagnetic-induced stress within the medium. Here, the optical force density is re-obtained through a new Lagrangian approach.
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•Impact of aggregates in Rhodamine 6G on the thermal and optical properties.•Energy transfers effect on the fluorescence quantum efficiency (η) of Rhodamine 6G.•Novel thermal load ...equation to correctly obtain η of monomers and aggregates.•Guideline for studying fluorescence efficiency of binary or complex systems.•Assessing microparameters via thermal lensing and optical spectroscopy.
Rhodamines constitute a class of dyes extensively investigated and applied in various contexts, primarily attributed to their high luminescence quantum yield. This study delves into the impact of aggregation on the thermal and optical properties of Rhodamine 6G (R-6G) solutions in distilled water. Examined properties encompass thermal diffusivity (D), temperature coefficient of the refractive index (dn/dT), fluorescence quantum efficiency (η), and energy transfer (ET). These parameters were assessed through thermal lens (TL) and conventional absorption and emission spectroscopic techniques. The dimerization of R-6G solutions was revisited, revealing that an increase in R-6G concentration alters the features of absorption and emission spectra due to dimer formation, resulting in unexpected behavior of η. Consequently, we introduce a novel model for the fraction of absorbed energy converted into heat (φ), which accounts for emissions from both monomers and dimers. Employing this model, we investigate and discuss the concentration-dependent behaviors of η for monomers (ηm) and dimers (ηd). Notably, our findings demonstrate that ηm values necessitate ηd = 0.2, a relatively substantial value that cannot be disregarded. Additionally, applying the Förster theory for dipole–dipole electric ET, we calculate microparameters for ET between monomers (CDD) and monomer–dimer (CDA). Critical ranges for ET in each case are quantified. Microparameter analysis indicates that ET between monomer–monomer and monomer–dimer species of R-6G dissolved in distilled water holds significance, particularly in determining ηm. These results bear significance, especially in scenarios involving high dye concentrations. While applicable to R-6G in water, similar assessments in other media featuring aggregates are encouraged.
•Optical thermometry applications of the Tm3+/Er3+/Sm3+ tri-doped TeO2-Li2O-ZnO (TLZ) glasses has been investigated.•The highest value of relative thermal sensitivity was 2.47 %K−1, with the FIR ...between the 530 nm and 458 nm emissions.•White-light emission was achieved by adjusting the doping concentration of Sm3+ ion.•The color coordinates CIE changed from white, (0.308, 0.317) at 299 K, to yellow, (0.416, 0.514) at 455 K.
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The potential of Tm3+/Er3+/Sm3+ tri-doped TeO2-Li2O-ZnO (TLZ) glasses for temperature sensors using color emissions and for generating white light sources was investigated. The samples were successfully synthesized by melting quenching technique in air atmosphere. We have used fixed concentrations of Tm3+ (0.2 mol%) and Er3+ (0.5 mol%) ions, and three Sm3+ concentrations: 0.2, 0.5, and 1.0 mol%. Particularly, we have analyzed the fluorescence intensity ratio (FIR) corresponding to the emissions of these ions as a function of the temperature. As a result, the highest value obtained to the relative thermal sensitivity was 2.47%K−1 for the FIR related to the emissions at 530 nm and 458 nm of the sample doped with 0.5 mol% of Sm3+. In addition, white-light emission was achieved by adjusting the doping concentration of Sm3+ ions. Moreover, we obtained a CIE color coordinates changing from white, (0.308, 0.317) at 299 K, to yellow, (0.416, 0.514) at 455 K. These results showed that these TLZ glasses are promising platforms for optical temperature sensing, for example, such as safety signal in high-temperature environment.
(100-X-Y)TeO2-XLi2O-YZnO, X = 10, 15 and 20, Y = 0, 5, 10, 15, 20, 25 and 30 mol%, glasses have been prepared by the melt quenching technique. Density and molar volume have been identified for every ...glass sample. Differential Scanning Calorimetry (DSC), optical absorption in the ultraviolet–visible region, Raman spectroscopy and linear refractive index have been achieved. DSC results show a considerable increase in glass stability with the replacement of TeO2 by ZnO. The Band Gap energy, determined from UV-VIS results, gradually increases in all set of samples. The Raman spectroscopy results confirm a structural change: with the increase of ZnO content (until TeO2 = 65 mol%), a decrease of non-bridging oxygens is verified, which decreases the polarizability of the system and increasing the Band Gap energy.
•The substitution of TeO2 by ZnO increases the thermal stability of TeO2-Li2O-ZnO glasses.•ZnO inhibits the effects of Li2O rearranging the non-bridging oxygens.•ZnO changes its role from former to modifier until TeO2 = 65 mol% content.•Ion oxide polarizability is extremely sensitive to the alteration in role of ZnO oxide.
We present a generalmodel based on fractional diffusion equation coupled with a kinetic equation through the boundary condition. It covers several scenarios that may be characterized by usual or ...anomalous diffusion or present relaxation processes on the surface with non-Debye characteristics. A particular case of this model is used to investigate the experimental data obtained from the drug release of the capsaicinoids-loaded Poly (ε-caprolactone) microparticles. These considerations lead us to a good agreement with experimental data and to the conjecture that the burst effect, i.e., an initial large bolus of drug is released before the release rate reaches a stable profile, may be related to an anomalous diffusion manifested by the system.
► Ce
3+-doped LSCAS glass exhibits broad, simultaneously blue and yellow emissions under UV excitation. ► In this phosphor is possible to continuously tune the emission, covering the entire visible ...spectrum. ► The ability to change the color temperature in accordance to the occasion is a feature of this glass system.
In this paper, we report results concerning tunable light emission and color temperature in cerium-doped low-silica-calcium-alumino-silicate (LSCAS) glass for smart white-light devices. Spectroscopic results, analyzed using the CIE 1931
x–
y chromatic diagram, show that this glass presents two broad emission bands centered at 475 and 540
nm, whose intensities can be tuned by the excitation wavelength. Moreover, the same emission can be achieved from a color temperature range from 3200 to 10,000
K, with a color-rendering index (CRI) of around 75% obtained by changing the optical path length of the sample. Our new phosphor LSCAS glass, which is a unique system that exhibits tunable yellow emission, combines all qualities for white-light devices.
We investigate the influence of the surface effects on a diffusive process by considering that the particles may be sorbed or desorbed or undergo a reaction process on the surface with the production ...of a different substance. Our analysis considers a semi-infinite medium, where the particles may diffuse in contact with a surface with active sites. For the surface effects, we consider integrodifferential boundary conditions coupled with a kinetic equation which takes non-Debye relation process into account, allowing the analysis of a broad class of processes. We also consider the presence of the fractional derivatives in the bulk equations. In this scenario, we obtain solutions for the particles in the bulk and on the surface.
We analyze the behavior of a system governed by a fractional diffusion equation with spherical symmetry and subjected to integro–differential boundary conditions which can simulate sorption, ...desorption and reaction processes. We consider the processes defined in terms of kinetic equations that couple the surface processes with the bulk dynamic enable us to describe scenarios where the surface modifies the bulk dynamics and this may change the behavior on surface. This problem is presented in terms of a general formulation satisfying the mass balance and a particular application characterized by a reversible process on the surface is analyzed. For this application, we obtain exact solutions in terms of the Green function approach and evaluate the concentrations on the spherical surface and in the bulk for different processes. These results lead to a rich class of scenarios which can be related to an anomalous diffusion.
This Letter reports the formation of Ti3+ in OH- free aluminosilicate glass melted under vacuum condition, with a very long lifetime (170 micros) and broad emission band shifted towards the visible ...region. This lifetime value was attributed to the trapping of the excited electrons by the glass defects and detrapping by thermal energy, and it is 2 orders of magnitude higher than those published for Ti3+ doped materials. Our results suggest that this glass is a promising system to overcome the challenge of extending the spectral range of traditional tunable solid state lasers towards the visible region.
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•Photoacoustic spectroscopy was used to identify chemical assignments of paracetamol in NIR.•Phase-resolved photoacoustic method is applied to characterization of paracetamol.•The ...peaks centered at 1398 and 1225nm were assigned to a C–H combination from a CH3 structure.•The peak centered at 1305nm was assigned to a C–H combination from the aromatic ring.
In this work, the phase-resolved photoacoustic method was applied to provide specific information on the chemical assignments of paracetamol in the near-infrared region. Two broad bands, centered at 1370 and 1130nm, were well-resolved using this method, making it possible to assign the peaks centered at 1398, 1355 and 1295nm to a C–H combination from a CH3 structure and the peak at 1305nm to a C–H combination from the aromatic ring. This information represents a new finding in chemical studies regarding this medicament.
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