Determination Of Absorption Coefficient Research Articles

Facile Z-scan determination of nonlinear refractive index and absorption coefficient of dye-doped polymer film

Facile Z-scan determination of nonlinear refractive index and absorption coefficient of dye-doped polymer film

"Exploring Aerated Autoclaved Concrete (AAC) Acoustic Properties Across Diverse Frequency Bands"

Aerated Autoclaved Concrete (AAC) stands out as an environmentally friendly and lightweight construction material. Known for its durability, load-bearing capacity, and excellent insulation, AAC surpasses traditional concrete blocks and red bricks in construction preferences. Its suitability as a wood alternative is evident, given its resistance to decay and comparable lightweight characteristics. Comprising a blend of cement, fly ash, limestone, and gypsum in an 8:69:20:3 ratio, with aluminum powder as the expansion agent, AAC serves as a versatile building material. In addition to its various attributes, understanding the acoustic properties of AAC is essential. Structures such as schools, hospitals, hotels, offices, and multi-family housing demand effective sound insulation, necessitating the use of materials with favorable sound absorption coefficients and minimal sound reflection coefficients. Due to its porous composition, Aerated Autoclaved Concrete exhibits notable sound absorption coefficients, making it ideal for applications in environments like schools and hospitals. This research delves into the determination of AAC's sound absorption coefficient and sound reflection coefficient across a spectrum of frequencies ranging from 1 kHz to 10 kHz. The analysis extends beyond frequency variations to encompass different sound intensities, offering a comprehensive exploration of AAC's acoustic characteristics.

Contribution of black carbon and desert dust to aerosol absorption in the atmosphere of the Eastern Arabian Peninsula

Discriminating the absorption coefficients of aerosol mineral dust and black carbon (BC) in different aerosol size fractions is a challenge because of BC's large mass absorption cross-section compared to dust. Ambient aerosol wavelength dependent absorption coefficients (babs) in supermicron and submicron size fractions were determined with a high time resolution. The measurements were performed simultaneously using identical systems at an urban and a regional background site in Qatar. At each site, measurements were taken by co-located Aethalometers, one with a virtual impactor (VI) and the other with a PM1 cyclone to respectively collect super-micron-enhanced and submicron fractions. The combined measurement of aerosol absorption and scattering coefficients enabled the particles to be classified based on their optical properties' wavelength dependence. The classification reveals the presence of BC internally/externally mixed with different aerosols. Helium ion microscopy images provided information concerning the extent of mineral dust in the submicron fraction. The determination of absorption coefficients during dust storms and non-dust periods was used to establish the absorption Ångström exponent for dust and BC. Non-parametric wind regression, potential source contribution function and back-trajectory analysis reveal major regional sources of desert dust associated with north-westerly winds and a minor local dust contribution. In contrast, major BC sources found locally were associated with south-westerly winds with a smaller contribution made by offshore emissions transported by north-easterly and easterly winds. The use of a pair of Aethalometers with VI and PM1 inlets separates contributions of BC and dust to the aerosol absorption coefficient.

Phytoplankton optical fingerprint libraries for development of phytoplankton ocean color satellite products

Phytoplankton respond to physical and hydrographic forcing on time and space scales up to and including those relevant to climate change. Quantifying changes in phytoplankton communities over these scales is essential for predicting ocean food resources, occurrences of harmful algal blooms, and carbon and other elemental cycles, among other predictions. However, one of the best tools for quantifying phytoplankton communities across relevant time and space scales, ocean color sensors, is constrained by its own spectral capabilities and availability of adequately vetted and relevant optical models. To address this later shortcoming, greater than fifty strains of phytoplankton, from a range of taxonomic lineages, geographic locations, and time in culture, alone and in mixtures, were grown to exponential and/or stationary phase for determination of hyperspectral UV-VIS absorption coefficients, multi-angle and multi-spectral backscatter coefficients, volume scattering functions, particle size distributions, pigment content, and fluorescence. The aim of this publication is to share these measurements to expedite their utilization in the development of new optical models for the next generation of ocean color satellites.

Self-referencing photothermal digital holographic microscope for characterization of low-loss liquids

Measurement of absorption coefficients of transparent samples is important for their characterization and identification; however, it is challenging to measure low values, e.g., 10−3–10−4 cm−1 with high accuracy. Here, we report a compact photothermal lateral shearing digital holographic device. It is based on the thermal lens effect and a common-path, self-referencing digital holographic microscope comprising a glass plate, probe beam, and a CMOS camera. The change in phase distribution caused by the temperature change due to light absorption is measured from the recorded holograms to extract the sample's absorbance and absorption coefficient. The feasibility of the proposed configuration is validated by the experimental results obtained with different concentrations of gold nanoparticles (AuNPs) in an aqueous solution. Determination of AuNPs concentration in the nM range is performed, and the obtained limits of detection and quantitation are 0.04 nM and 0.13, respectively. The calibration curve is linear at a low concentration range of 0.06–0.95 nM with 1% reproducibility. In addition, the method's versatility is demonstrated by measuring the absorption coefficient of low-loss solvents, such as ethanol and water. The determined absorption coefficients agree with the reported values, confirming that this method provides good spectrometric capabilities, such as high sensitivity and accuracy.

Phonon-assisted optical absorption of SiC polytypes from first principles

Silicon carbide (SiC) is an indirect-gap semiconductor material widely used in electronic and optoelectronic applications. While experimental measurements of the phonon-assisted absorption coefficient of SiC across its indirect gap have existed for more than 50 years, theoretical investigations of phonon-assisted absorption have been hampered by their excessive computational cost. In this work, we calculate the phonon-assisted temperature-dependent optical absorption spectra of the commonly occurring SiC polytypes (3C, 2H, 4H, 6H, and 15R), using first-principles approaches based on density functional theory and related techniques. We show that our results agree with experimentally determined absorption coefficients in the spectral region between the direct and indirect band gaps. The temperature dependence of the spectra can be well predicted with taking the temperature dependence of the band gaps into account. Lastly, we compare the spectra obtained with second-order perturbation theory to those determined by the special displacement method and we show that the full consideration of the electronic energy renormalization due to temperature is important to further improve the prediction of the phonon-assisted absorption in SiC. Our insights can be applied to predict the optical spectra of the less common SiC polytypes and other indirect-gap semiconductors in general.

Determination of the Strain Influence on the InAs/InAsSb Type-II Superlattice Effective Masses.

A3B5 materials used for the superlattice (SL) fabrication have properties that enable the design of devices optimized for infrared (IR) detection. These devices are used in the military, industry, medicine and in other areas of science and technology. The paper presents the theoretical assessment and analysis of the InAs/InAs1-xSbx type-II superlattice (T2SL) (grown on GaSb buffer layer) strain impact on the bandgap energy and on the effective masses of electrons and holes at 150 K. The theoretical research was carried out with the use of the commercial program SimuApsys (Crosslight). The k·p method was adopted in T2SL modeling. Luttinger coefficients (γ1, γ2 and γ3) were assessed assuming the Kane coefficient F = 0. The bandgap energy of ternary materials (InAsxSb1-x) was determined assuming that the bowing parameter (bg) for the above-mentioned temperature is bg = 750 meV. The cutoff wavelength values were estimated based on the theoretically determined absorption coefficients (from approximation the quadratic absorption coefficient). The bandgap energy was calculated according to the following formula: Eg = 1.24/λcutoff. The theoretical simulations allowed us to conclude that the strain in T2SL causes the Eg shift, which also has an impact on the effective masses me and mh, playing an important role for the device's optical and electrical performance. The T2SLs-simulated results at 150 K are comparable to those measured experimentally.

Terahertz Time-Domain Spectroscopy in Reflection Configuration for Inorganic and Mineral Pigment Identification.

This work demonstrates terahertz time-domain spectroscopy (THz-TDS) in reflection configuration on a class of inorganic and mineral pigments. The technique is validated for pictorial materials against the limitations imposed by the back-reflection of the THz signal, such as weak signal intensity, multiple signal losses and distortion, as well as the current scarce databases. This work provides a detailed description of the experimental procedure and method used for the determination of material absorption coefficient of a group of 10 pigments known to be used in ancient frescoes, that are, Cu-based (azurite, malachite, and Egyptian blue), Pb-based (minium and massicot), Fe-based (iron oxide yellow, dark ochre, hematite, and Pompeii red) pigments and mercury sulfide (cinnabar), and classified the vibrational modes of the molecular oxides and sulfides for material identification. The results of this work showed that the mild signal in reflection configuration does not limit the application of THz-TDS on inorganic and mineral pigments as long as (i) the THz signal is normalized with a highly reflective reference sample, (ii) the secondary reflected signals from inner interfaces are removed with a filtering procedure, and (iii) the limitations at high frequencies imposed by the dynamic range of the instrument are considered. Under these assumptions, we were able to differentiate molecular phases of the same metal and identify azurite, Egyptian blue, minium, and cinnabar, isolating the molecular vibrations up to 125 cm-1. The established approach demonstrated to be reliable, and it can be extended for the study of other materials, well beyond the reach of the heritage domain.

Absorption Coefficient of Bulk III-V Semiconductor Materials: A Review on Methods, Properties and Future Prospects

Over the last few decades, research works have focused on elucidating the optical properties of semiconductor materials. Despite remarkable progress in the measurement and calculation of the absorption coefficient for semiconductor materials, there is a lack of comprehensive review on the comparative study of absorption coefficient properties for different types of bulk semiconductor materials and their methods for calculating the absorption coefficient. Hence, this paper summarizes the fundamentals of the various methods used to determine the absorption coefficient properties of bulk growth semiconductor crystals, and discusses their advantages and disadvantages. Furthermore, this review provides comprehensive results from recent studies and findings on the absorption properties of near- to mid-infrared (wavelengths from 800 to 7300 nm) group III-V semiconductor materials. In addition, the absorption coefficient of the conventional group IV semiconductors (silicon and Ge) were included for performance comparison. Critical analysis was done for the reviewed materials concerning their material properties, such as band gap structure, crystal quality, and the structural design of the device. The related studies on the methods to determine the absorption coefficients of semiconductors and to improve the likelihood of absorption performance were well highlighted. This review also provides an in-depth discussion on the knowledge of absorption coefficient based on a wide range of semiconductor materials and their potential for sensors, photodetectors, solar and photovoltaic application in the near to mid infrared region. Lastly, the future prospects for research on absorption coefficients are discussed and the advancement in the determination of absorption coefficients for new ternary and quaternary materials is proposed using artificial intelligence such as neural networks and genetic algorithm.

Determination of Nonlinear Refraction and Absorption Coefficient of MO/PVA film Using a Radially Varying Aperture Scan Method

Determination of Nonlinear Refraction and Absorption Coefficient of MO/PVA film Using a Radially Varying Aperture Scan Method

Effect of laser ablated gold nanoparticles on the nonlinear optical properties of π-extended BODIPY dyes

Dipyrromethene boron difluoride (BODIPY) and its derivatives have attracted considerable interest due to their remarkable photophysical properties beneficial for developing fluorescent sensors, biolabels, photodynamic therapy agents, photonic materials, and so on. Herein, we report gold nanoparticles (AuNPs) induced modulation of nonlinear optical properties of π-extended BODIPY derivatives BPA and BDIPA. The spherical gold nanoparticles with an average particle size of 11 ± 3.5 nm were synthesized by pulsed laser ablation technique and characterized by transmission electron microscopy and dynamic light scattering. The interaction of AuNPs with the dye molecules was confirmed by UV/vis absorption and steady-state emission spectroscopy studies. Further, the dual-beam thermal lens technique was used to validate dye-nanoparticle interaction. The thermal diffusivity values of the samples at an excitation wavelength of 532 nm were measured and found that the overall heat diffusion was slower in the AuNPs added samples than that of the dye alone sample, corroborating dye-nanoparticle interaction. The third-order nonlinear optical absorption properties of the samples were investigated by using the Z-scan technique in the infrared region (1064 nm). The open aperture configuration shows significant reverse saturable absorption characteristics for all the samples. Determination of nonlinear absorption coefficient for the dye samples at different input intensities identified two-photon absorption as the important mechanism that produces reverse saturable absorption. The AuNPs incorporated dye samples showed a substantial enhancement in the nonlinear optical behavior. The nonlinear absorption coefficient of the AuNPs incorporated dye samples (10 cm/GW) was enhanced almost two times than that of dye alone samples (5 cm/GW). The enhanced nonlinearity is attributed to the intense local field effect of AuNPs.

A comparison of methods for estimating euphotic depths in the Great Lakes from satellite observations

Because it defines the vertical extent of the zone of active photosynthesis, an estimate of the euphotic depth (Zeu), the depth in the water column at which the intensity of photosynthetically available radiation (PAR) is reduced to 1% of the intensity just below the surface, is a critical component of both depth resolved and vertically integrated numerical models of aquatic primary production. In recent years these models have become more detailed in both space and time and it is necessary to make estimates of Zeu at the same spatial and temporal scales. In large bodies of water such as the Great Lakes, satellite remote sensing is the only practical method available to provide such estimates at the needed resolution, but the algorithms used for estimating Zeu from satellite observations have not been rigorously tested in the Great Lakes. To assess these methods we used measurements of the vertical profile of PAR collected as part of the U.S. EPA’s, Great Lakes National Program Office (GLNPO) annual monitoring program to estimate Zeu. We compared the field measurements to satellite-derived estimates of Zeu obtained from a variety of algorithms ranging from simple empirical relationships to more complicated methods based on the inherent optical properties of the water. We found that an algorithm based on a quasi-analytic determination of absorption and backscatter coefficients that also incorporates a depth-dependent attenuation coefficient performed best.

Determination of water absorption coefficient of unfired earth materials different in used clay and ratio of components

The paper is focused on unfired rammed earth and its water absorption properties. Increasing the utilization of raw natural materials can be one of the approaches towards sustainable development. Different prescriptions were designed and specimens were rammed. Then they were put in the covering of nylon and settled in the box with soft foam that was moistened. The level of moistening was constant. The specimens were regularly weighted. Specimens with montmorillonite clay have the highest values of the water absorption coefficient. Montmorillonite clay has a higher binding capacity. The values are compared to values that were found in the literature. Then the maximal capillary water capacity by area was determined.

Research of technological properties of Medicinal Plant raw material of Siberian Statice (Limonium gmelinii)

the article presents the results of studying the technological properties of medicinal plant raw materials Siberian Statice (Limonium gmelinii), namely specific, volumetric, bulk density, determination of absorption coefficient and swelling rate, as well as porosity, free volume layer and fractional composition. Grinded raw materials from the aboveground part of Siberian Statice, which included stems, inflorescences, flowers was the object of the study. Siberian Staticea (Limonium gmelinii) is a perennial herbaceous bare plant of the Kermek genus, which contains tannins, flavonoids, hydroxycinnamic acids, anthocyanins, coumarins, carbohydrates, polysaccharides, organic acids, amino acids and others. The raw material in the Genichesk district of the Kherson region was harvested in 2021. The study of basic technological properties was carried out according to generally accepted methods, which are listed in the State Pharmacopoeia of Ukraine. The data obtained during the study indicate that the composition of the grinded raw material is polydisperse and it is not possible to determine one predominant fraction. Particles with a size of 2,8-1,0 mm are about 80% of the composition. This diversity of composition can be explained by the fact that the studied aboveground part of plant raw materials includes a thick-branched stem, inflorescences with small regular flowers. The humidity of the studied raw materials is 0,23%. The specific density of raw materials is 1,3446 ± 0,0073 g/cm3, and the volumetric density of plant raw materials is 0,4679 ± 0,0450 g/cm3. Bulk mass after shrinkage decreased from 80 to 69, which is 13,75%. Volumetric shrinkage increased from 0,1251 g/cm3 to 0,1436 g/cm3. Indicators of porosity, porosity and free volume layer (0,6933 g/cm3, 0,7326 g/cm3, 0,9073 g/cm3, respectively) are quite high, which indicates a good absorption capacity of raw materials. The average value of the absorption coefficient was 6,33 ± 0,34, which indicates a high cost of extractant, and the swelling rate shows that the investigated raw material doesn’t swell, this indicates the presence of pores inside the stem, where the extractant is retained, but does not increase linear dimensions and volume plant raw materials. The technological properties of Siberian Statice (Limonium gmelinii) raw materials have been experimentally determined, which allow choosing the optimal extraction methods for the studied raw materials, namely the extraction method, the ratio of raw materials: extractant, the nature of the extractant.

Determination of water absorption coefficients for some medicinal plant raw materials

Determination of water absorption coefficients for some medicinal plant raw materials

Direct determination of molar absorption coefficients of several molecules in the lowest excited singlet states.

Molar absorption coefficient of the lowest excited state is an indispensable information for the quantitative investigation of photochemical reactions by means of transient absorption spectroscopy. In the present work, we quantitatively estimated the molar absorption coefficients of the S1 state of the solute in three solution systems, Rhodamine B in ethanol, ZnTPP in DMF and N,N'-bis(2,6-diisopropylphenyl)terrylene-3,4,11,12-tetracarboxydiimide (TDI) in chloroform, by perfectly bleaching the ground state molecules using the picosecond 532-nm laser pulse with a large number of photons. These solution systems were selected because no obvious photodegradation was detected in the present range of the excitation intensity. The molar absorption coefficient obtained by this method was verified by the numerical analysis of the excitation intensity dependence of the transient absorbance by taking into account the inner filter effect (absorption of the excitation light by the S1 state produced by the leading part of the pump pulse) and the decrease of the ground state molecules by the pump process (depletion). In addition, these molar absorption coefficients were confirmed by the comparison of relations between the excitation intensity and the transient absorbance of the S1 state under the condition where the fraction of the excited solute is ≪ 10% by the femtosecond pulsed laser excitation. From these results, the error of the molar absorption coefficients was estimated to be < 5%. These values can be used as reference ones for the estimation of molar absorption coefficients of other systems leading to the quantitative elucidation of the photochemical reactions detected by the transient absorption spectroscopy.

Hyperspectral optical absorption closure experiment in complex coastal waters

AbstractAccurate measurements of absorption data are required for the development and validation of inversion algorithms for upcoming hyperspectral ocean color imaging sensors, such as the NASA Phytoplankton, Aerosol, Cloud, and ocean Ecosystem mission. This study aims to provide uncertainty estimates associated with leading approaches to measure hyperspectral absorption coefficients in complex coastal waters. Absorption spectra were collected at 12 different stations, all located in the Indian River Lagoon, Florida, USA, between 09 January 2017 and 13 January 2017. Measurements included spectral absorption coefficients in the visible range (400–700 nm) associated with dissolved, aCDOM, total particulate, ap, and total nonwater, anw, fractions, and were made both in situ and from discrete samples. Discrete sample approaches included dual‐beam spectrophotometer, liquid waveguide capillary cell, point‐source integrating cavity absorption meter (PSICAM) for dissolved matter absorption samples, and quantitative filter technique ICAM measurements and the dual‐beam spectrophotometer with center‐mounted integrating sphere filter pad technique, while the Turner Designs ICAM, and WET Labs AC‐s, and AC‐9 instruments were used to determine absorption coefficients in situ. The Gershun approach, determining absorption from measurement of the irradiance quartet with respect to depth was also assessed in situ. Measurement uncertainties and relative accuracies were quantified for each of these approaches. Results showed generally strong agreements between different discrete sample methods, with average percent absolute error %δabs &lt; 7% for aCDOM and &lt; 9% for ap. In situ approaches showed higher variability and reduced accuracy. For anw, %δabs deviation relative to PSICAM data was on average 12% to 20%. Results help identify remaining technological gaps and need for improvements in the different absorption measurement approaches.

Investigation on the optical properties of (PVP/PVA)/Al2O3 nanocomposite films for green disposable optoelectronics

The ultraviolet–visible (UV–Vis) range (200–800 nm) optical behaviour of nanocomposite films consisted of poly (vinyl pyrrolidone)/poly (vinyl alcohol) (PVP/PVA) blend matrix and alumina (Al2O3) nanofiller (1–5 wt%) was characterized for their eco-friendly green technology-based optoelectronic device applications. Absorbance, transmittance, and reflectance spectra of the (PVP/PVA)/Al2O3 films were analyzed to determine absorption coefficient, energy band gaps (direct and indirect), and Urbach energy. The non-linear decrease in band gap values of these composites with increasing amount of Al2O3 in the polymer matrix was explained. The wavelength-dependent values of refractive index, extinction coefficient, complex dielectric permittivity, and optical conductivity of these hybrid nanocomposites enhanced non-linearly with increasing filler concentration, as well as the dispersive energy, single oscillator strength, and optical susceptibility increased gradually. All these optical parameters values of the (PVP/PVA)/Al2O3 nanocomposites are found controllable by Al2O3 contents and reasonably comparable with the results of other similar types of composites.

From the leather industry to building sector: Exploration of potential applications of discarded solid wastes

The leather industry is an example of circular economy, as it uses meat industry wastes (hides and skins) as raw materials. However, the process of tanning also produces a substantial amount of organic waste. This research project studies the case of a tannery located in Navarra, in the North of Spain, committed to a circular economy and environmental protection, which produces around 2 tons per day of leather shavings and buffing dust and 10 tons per day of discarded bullock hair. The study tackles the challenge of whether the discarded waste material might be used as a new resource for products or processes related with the building sector. Three different types of solid wastes (chromium free tanned shavings, chromium buffing dust, and discarded hair) were categorized and analyzed. The paper examines two proposals to reuse the weekly tons of leftovers (both shavings and hair) produced by the tannery, instead of taking them to an external composting plant or to the landfill. The first exploration path proposed to use the discarded material to obtain biomass for the company’s thermal production plant. After establishing the calorific values of the discarded hair and the shavings, these were found to offer competitive value in comparison with the biomass products used at present, such as wood pellets. The second approach to the waste upcycling involved seeking new products in the building sector, acoustic panels in this case. After a mechanical behavior analysis, different binders were blended with diverse proportions and particle sizes of shavings to obtain samples for a sound absorption coefficient determination. The results show coefficients close to those of cork panels or carpets. This experimental experience serves as a preliminary study for the use of leather industry wastes in the construction sector. • Further circular economy in leather industry: two proposals for industrial symbiosis. • Holistic approach for waste material recycling challenge. • Recycling tools for a market of more than US$100 billion per year. • Use of waste as biomass might reduce by more than half the dependency on natural gas. • Competitive performance of leather by-products as acoustic absorption panels.

Possibilities of disposing silica fume and waste glass powder, which are environmental wastes, by using as a substitute for Portland cement.

In this study, the possibilities of disposal of environmental waste, silica fume, and waste glass powder as substitutes in the mortar samples in Portland cement were investigated. For this purpose, Portland cement (CEM I), silica fume (SF), waste glass powder (WGP), CEN standard sand, and water were used in mortar production. Additive cements were obtained by using the SF, WGP, and SFWGP substitution methods in Portland cement at the rates of 10, 20, 30, and 40%. The flexural strength, compressive strength, radiation permeability (determination of linear absorption coefficient), high temperature, and alkali-silica reaction (ASR) effect on SF, WGP, and SFWGP were examined and compared with the control PC 42.5R samples. Mortar samples of 40 × 40 × 160 mm size were obtained with the grouts/mortars produced, and the samples were exposed to five temperature effects, namely, 20, 150, 300, 700, and 1000 ° C. Samples kept at 20 ° C are accepted as baseline. A total of 429 samples were studied, including the cooling process in the air (spontaneously in the laboratory, 20 ° C ± 2). After the samples achieved room temperature, flexural and compressive strength tests were carried out at 28 and 90 days. Test results demonstrate that SF, WGP, and SFWGP, which are environmental wastes, can be disposed both as a pozzolanic additive material both alone and together in cement mortars, can be utilized in buildings with high fire hazard, and the sample with the highest linear absorption coefficient is the sample obtained with SFWGP, and also, the expansion values ​​that occur in SF and WGP are less than the control sample.