Spectral Optical Properties Research Articles

Comparing the linear and non-linear optical properties of keto-enol forms of N-alkyl, N-aryl, and O-alkyl substituted 2-Hydroxybenzophenone

The Geometrical, electronical, spectral, linear, and non-linear optical properties (NLO) of keto-enol forms of 2-hydroxybenzophenone (2-HBp) derivatives were examined. Ten pairs of 2-HBp derivatives having D-π-A framework with N-alkyl (ethyl, julolidine), N-aryl (phenyl), O-methyl, groups as donor, phenyl ring as aspacer, and carbonyl group linked to phenyl ring consisting of either mono or dicarboxylic acid group as acceptor, were selected. DFT results suggest thatthe keto form is stablein the S0 and S1 states. Further, IR spectra, CV analysis, experimental absorption maxima, and TD-DFT results support the existence of 2-HBp derivatives in keto form. Thermogravimetric analysis shows that 2-HBp derivatives have remarkable thermal stability (∼200 °C), enabling their practical application in NLO. Further, DFT and TD-DFT results show that theketo form of 2-HBp derivatives with lower BLA, higher μ, ω, η, Γ, and hyperpolarizability exhibits superior NLO properties compared to theenol form of 2-HBp derivatives.

Tutorial on the Use of the Photon Diffusion Approximation for Fast Calculation of Tissue Optical Properties.

Computer simulations, which are performed at a single wavelength at a time, have been traditionally used to estimate the optical properties of tissues. The results of these simulations need to be interpolated. For a broadband estimation of tissue optical properties, the use of computer simulations becomes time consuming and computer demanding. When spectral measurements are available for a tissue, the use of the photon diffusion approximation can be done to perform simple and direct calculations to obtain the broadband spectra of some optical properties. The additional estimation of the reduced scattering coefficient at a small number of discrete wavelengths allows to perform further calculations to obtain the spectra of other optical properties. This study used spectral measurements from the heart muscle to explain the calculation pipeline to obtain a complete set of the spectral optical properties and to show its versatility for use with other tissues for various biophotonics applications.

Spectral and Linear Optical Properties for New Mixture of Nile Blue and Malachite Green Organic Laser Dyes

Spectral and Linear Optical Properties for New Mixture of Nile Blue and Malachite Green Organic Laser Dyes

Investigations on the growth, spectral, optical, electrical, thermal and nonlinear optical properties of L-valine itaconic acid single crystal

A nonlinear optical single crystal of L-Valine Itaconic Acid (LVIA) was grown at room temperature from an aqueous solution by using the slow evaporation method. The grown crystal was undergone X-ray diffraction investigation, which confirm that the crystal belongs to orthorhombic system with the non-centro symmetric Pbca space group. This single crystal contains several functional groups, according to FTIR spectroscopic analysis there were identified. By analyzing the crystal's UV–visible spectrum, based on its optical transparency this crystal may use for optoelectronic device manufacturing. The emission happens at 553 nm wavelength, according to the photoluminescence spectrum. Thermo gravimetric and differential thermal analytical studies helps us to measure title crystal melting point and thermal stability. At various temperatures, the dielectric property of the crystal was found out. The Kurtz-powder method has been used to study the phenomenon of Second Harmonic Generation (SHG) in the crystal.

Dependence of Virial Factors on Optical Spectral Properties of Active Galactic Nuclei

Reverberation mapping (RM) has long been a powerful tool for measuring the masses of supermassive black holes (SMBHs) at the centers of active galactic nuclei (AGNs), but the precision of these mass measurements depends on the so-called virial factors. It has been demonstrated that the virial factors exhibit significant diversity, spanning approximately 1–2 orders of magnitude across different AGNs. However, the underlying physical drivers for the diversity have not yet been finalized. Here, adopting the SMBH mass–spheroid luminosity relations of inactive galaxies with different bulge classifications, we calibrate the virial factors corresponding to the AGNs with pseudobulges (PBs) and classical bulges (or elliptical hosts, CBs) using the latest nearby RM sample. We investigate the correlations between virial factors and the AGN spectral properties, and find that for both PB and CB samples, the FWHM-based virial factors exhibit significant anticorrelations with the emission-line widths and profiles, while the σ line-based virial factors only show moderate anticorrelations with line widths for PBs. We attribute these correlations mainly to the inclination angle or opening angle of the broad-line regions. Moreover, we establish new relations to give more precise virial factors and, in combination with the latest iron-corrected radius–luminosity relation, tentatively develop new single-epoch estimators of SMBH masses, which enable more accurate measurements of SMBH masses in large AGN samples.

A comparative theoretical study on the structural, spectral, microtopology exploration (ELF, RDG, IRI, TDM), NBO and nonlinear optical properties of Red170 from different solvents and substituents

The effect of solvents and substituents on the C.I. Pigment PR170, the best known member of the naphthol red family, is investigated. Both PR170 and its alkoxy derivatives were analyzed using FTIR, 1H NMR and UV–Vis spectroscopy. The study included the evaluation of the average local ionization energy (ALIE), MEP, HOMO-LUMO analysis. The nature of intra- and intermolecular contacts in the crystal structure was also investigated using crystal packing and Hirshfeld surface analysis. Covalent and non-covalent interactions in PR170 were comprehensively described by IRI, RDG and ELF. In addition, Natural Bonding Orbital (NBO) and Fukui function calculations were performed. An analysis of the UV–Vis electronic transitions for different solvents was carried out, providing insight into the charge transfer processes within both PR170 and its derivatives. In particular, the research indicated a CT-type excitation at the S2 level during the hole-electron transfer analysis. The NLO results showed that PR170 is a promising candidate for nonlinear optical materials.

Estimation and model performance of aerosol radiative forcing from Radiative Transfer models using the AERONET data over Kenya, East Africa

The rapid economic growth and a lack of strict implementation of air quality regulations have led to unqualified effects on health, the environment, and the climate. In recent years, there has been an urgent need for the increased characterization of aerosols in terms of optical, micro-physical, and radiative properties and their climatic impacts. In the present study, the aerosol-climate implications were evaluated by aerosol radiative forcing (ARF) at three environmentally specific sites, Malindi (3° S, 40.2° E, 12 m asl), Mbita (0.42° S, 34.20° E, 1125 m asl), and Nairobi (1.0° S, 36.0° E, 1650 m asl), located in Kenya. The aerosol optical properties such as aerosol optical depth (AOD440), single scattering albedo (SSA440), asymmetric parameter (ASY440), and Ångström exponent (AE440-870) showed significant annual and seasonal heterogeneities. They noticed high (low) values during the local dry (wet) seasons, attributed to changes in anthropogenic activities, emission sources, and prevailing dynamics played by the meteorology. The study also utilized measured spectral aerosol optical properties and two radiative transfer models in the short-wave (SW) and long-wave (LW) regions with their respective spectral bands (0.2–4.0 µm) and (4.0–100.0 µm) during 2007–2018. The direct ARF simulated in the SW using the Santa Barbara DISORT Atmospheric Radiative Transfer Model (SBDART) and the Coupled Ocean and Atmospheric Radiative Transfer models (COART) depicted high correspondence, evidenced by relatively high (r > 0.64) correlations over the three sites. The ARF simulated by the two models in the SW and LW regions exhibited significant seasonal heterogeneity, with maximum (minimum) values observed during the local dry (wet) seasons. The results from the present study could form a basis for other climate change studies and increase the accuracy of the existing climate models to enhance climate forecasting over the East Africa region.

Experimental and DFT perspectives: exploring spectral, linear and nonlinear optical properties of p-nitrophenol complex crystal for NLO applications

Experimental and DFT perspectives: exploring spectral, linear and nonlinear optical properties of p-nitrophenol complex crystal for NLO applications

Gemini Near Infrared Spectrograph−Distant Quasar Survey: Rest-frame Ultraviolet−Optical Spectral Properties of Broad Absorption Line Quasars

We present the rest-frame ultraviolet−optical spectral properties of 65 broad absorption line (BAL) quasars from the Gemini Near Infrared Spectrograph−Distant Quasar Survey (GNIRS-DQS). These properties are compared with those of 195 non-BAL quasars from GNIRS-DQS in order to identify the drivers for the appearance of BALs in quasar spectra. In particular, we compare equivalent widths and velocity widths, as well as velocity offsets from systemic redshifts, of principal emission lines. In spite of the differences between their rest-frame ultraviolet spectra, we find that luminous BAL quasars are generally indistinguishable from their non-BAL counterparts in the rest-frame optical band at redshifts 1.55 ≲ z ≲ 3.50. We do not find any correlation between BAL trough properties and the Hβ-based supermassive black hole masses and normalized accretion rates in our sample. Considering the Sloan Digital Sky Survey quasar sample, which includes the GNIRS-DQS sample, we find that a monochromatic luminosity at rest-frame 2500 Å of ≳1045 erg s−1 is a necessary condition for launching BAL outflows in quasars. We compare our findings with other BAL quasar samples and discuss the roles that accretion rate and orientation play in the appearance of BAL troughs in quasar spectra.

Exploring the spectral and nonlinear optical properties of phenyl isothiocyanate through density functional theory and molecular docking studies: A comprehensive analysis of a potent biologically active phytochemical

Quantum chemical calculations employing Density Functional Theory (DFT) with 6–31G (d,p) basis sets have yielded valuable insights into the molecular structure, Frontier Molecular Orbitals (FMOs), Mulliken Charges, and Molecular Electrostatic Potential Maps of the phenyl isothiocyanate (PITC) molecule. Spectral analysis of PITC has been conducted including Fourier transform infrared (FTIR), Fourier transform Raman (FT-RAMAN), Nuclear Magnetic Resonance (NMR), and ultraviolet–visible (UV–Vis) spectroscopy by theoretical method. Additionally, global descriptive parameters and thermal properties have also been determined. The Nonlinear Optical characteristic (NLO) has been assessed in the gas phase using the same level of theory. The investigation into toxicity revealed that the studied molecule exhibits drug-like characteristics and is non-toxic. Molecular docking studies have been employed to investigate hydrogen bond interactions, elucidating the minimal binding energy of the compound. The outcomes of the docking studies strongly suggest the significant biological activity of Phenyl Isothiocyanate, emphasizing its potential as a potent phytochemical.

Sensitivities of Spectral Optical Properties of Dust Aerosols to Their Mineralogical and Microphysical Properties

AbstractDust aerosol is a key component in global radiative forcing and climate modeling. We developed a mineralogy‐resolved spectral optical property model for dust aerosols. The model incorporates nine mineral groups and applies the effective medium methods to obtain the spectral complex refractive indices of inhomogeneous dust particles. This study considers 5,000 sets of dust mineral composition mixtures along with the use of the bimodal particle size distribution. We calculate the bulk properties of these samples in a wide spectral range from 0.2 to 50 μm using a comprehensive database of hexahedral dust single‐scattering properties. Through sensitivity analyses, this study reveals that the illite and hematite components substantially affect the optical properties of dust. Furthermore, the effective radii of both the fine‐mode and the coarse‐mode dust particles have significant impacts on the bulk optical properties, albeit to varying degrees.

Seasonality of spectral radiative fluxes and optical properties of Arctic sea ice during the spring–summer transition

The reflection, absorption, and transmittance of shortwave solar radiation by sea ice play crucial roles in physical and biological processes in the ice-covered Arctic Ocean and atmosphere. These sea-ice optical properties, particularly during the melt season, significantly impact energy fluxes within and the total energy budget of the coupled atmosphere-ice-ocean system. We analyzed data from autonomous drifting stations to investigate the seasonal evolution of the spectral albedo, transmittance, and absorptivity for different sea-ice, snow, and surface conditions measured during the MOSAiC expedition in 2019–2020. The spatial variability of these properties was small during spring and increased strongly after melt onset on May 26, 2020, when liquid water content on the surface increased, largely accounting for the enhanced variability. The temporal evolution of surface albedo and sea-ice transmittance was mostly event-driven, thus containing episodic elements. Melt ponds reduced the local surface albedo by 31%–45%. Over the melting season, single ponding events increased the energy deposition of the sea ice by 35% compared to adjacent bare ice. Thus, single melt ponds may impact the summer energy budget as much as seasonal evolution over 1 month. Absorptivity and transmittance showed strong temporal and spatial variabilities independently of surface conditions, possibly due to the different internal sea-ice properties and under-ice biological processes. The differences in seasonal evolution shown for different sea-ice conditions strongly impacted the partitioning of shortwave solar radiation. This study shows that the formation and development of melt ponds, in reducing albedo by a third of bare ice sites, can notably increase the total summer heat deposition. The vastly different seasonal evolutions, different sea-ice conditions, and timing and duration of ponding events need to be considered when comparing local in-situ observations with large-scale satellite remote sensing datasets, which we suggest can help to improve numerical models.

Optical transmission modulation and spectral properties of self-organized nematic domains

The modulation and spectral characteristics of self-organized ensembles of nematic domains with the disclination lines non-aligned and aligned in a magnetic field have been studied using an electric field. The obtained experimental voltage dependences of the light transmission agree well with the dependences calculated using the model considerations. These dependences have been compared with the electro-optical characteristics of a homogeneous planar nematic layer. The amplitude component of the optical transmission determined by light scattering and the oscillating component caused by the phase modulation have been examined. The effect of the spectral dispersion of transmission on the electro-optical characteristics of domain ensembles has been evaluated.

DFT assessments of optical and thermoelectric characteristics of (III/V)-doped elements into graphene sheets

First-principles simulations are conducted to explore the structural stability, electronic properties, and optical responses of pristine and boron- or nitrogen-doped monolayers graphene. The computed electronic density of states revealed that the substitutional doping of boron impurity atoms on monolayer graphene (MLG) shifts the Dirac point upward, although the substitution of nitrogen impurity atoms in graphene pushes the Dirac point downward the Fermi level. This could exhibit that upon the doping of MLG with boron or nitrogen, respectively, p-type or n-type semimetal is acquired. The overall optical spectral properties of the substituted graphene with boron or nitrogen atoms are simulated and compared with the optical spectra results of pure graphene. The optical features of pristine and doped MLG are determined by taking the interband and intra-band transitions into account ranging from the far-infrared to the ultraviolet regime of the electromagnetic radiation. A remarkable red shift in the optical spectra of the doped MLG towards the visible regime of radiation is established. An enhanced reflectivity illustrated that concentration-dependent optical properties of boron and nitrogen-doped MLG happen at lower electromagnetic radiation regimes. In addition, we explored the thermoelectric behaviors of the pristine/doped graphene monolayers with [Formula: see text] supercells. We found a significant improvement in the electrical conductivity of graphene when doped with boron or nitrogen impurities. However, an increase in the electrical conductivity has textured a decrease in the Seebeck coefficients. Improvement in the electrical conductivity is attributed to an interesting effect on the graphene monolayers’ power factor (PF). These findings indicate a positive impact of the dopants on the thermoelectric properties of graphene monolayers and reveal that they are potential materials for thermoelectric applications and nanodevices.

Green route to prepare zinc oxide nanoparticles using Moringa oleifera leaf extracts and their structural, optical and impedance spectral properties

This article investigates biosynthesis of zinc oxide (ZnO) nanoparticles (NPs) from Moringa oleifera leaves extract using an eco-friendly preparation method. The crystalline structure, optical properties, morphology and impedance characteristics of ZnO NPs were analyzed using impedance spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR) and ultraviolet spectroscopy (UV-vis). The powder XRD pattern confirmed the crystallinity of the prepared samples as well as enabled determining their crystallite size and pure phase portion. The FTIR study confirmed the presence of functional groups responsible for reduction metal ions into ZnO NPs. UV-vis absorption spectra contained the absorption peak corresponding to ZnO NPs. Impedance spectroscopy of the prepared ZnO NPs revealed the grain boundaries in them and confirmed their semiconducting nature.

Higher absorption enhancement of black carbon in summer shown by 2-year measurements at the high-altitude mountain site of Pic du Midi Observatory in the French Pyrenees

Abstract. Black-carbon-containing particles strongly absorb light, causing substantial radiative heating of the atmosphere. The climate-relevant properties of black carbon (BC) are poorly constrained in high-altitude mountain regions, where many complex interactions between BC, radiation, clouds and snow have important climate implications. This study presents 2-year measurements of BC microphysical and optical properties at the Pic du Midi (PDM) research station, a high-altitude observatory located at 2877 m above sea level in the French Pyrenees. Among the long-term monitoring sites in the world, PDM is subject to limited influence from the planetary boundary layer (PBL), making it a suitable site for characterizing the BC in the free troposphere (FT). The classification of the dominant aerosol type using aerosol spectral optical properties indicates that BC is the predominant aerosol absorption component at PDM and controls the variation in single-scattering albedo (SSA) throughout the 2 years. Single-particle soot photometer (SP2) measurements of refractory BC (rBC) show a mean mass concentration (MrBC) of 35 ng m−3 and a relatively constant rBC core mass-equivalent diameter of about 180 nm, which are typical values for remote mountain sites. Combining the MrBC with in situ absorption measurements, a rBC mass absorption cross-section (MACrBC) of 9.2 ± 3.7 m2 g−1 at λ=880 nm has been obtained, which corresponds to an absorption enhancement (Eabs) of ∼2.2 compared to that of bare rBC particles with equal rBC core size distribution. A significant reduction in the ΔMrBC/ΔCO ratio when precipitation occurred along the air mass transport suggests wet removal of rBC. However we found that the wet removal process did not affect the rBC size, resulting in unchanged Eabs. We observed a large seasonal contrast in rBC properties with higher MrBC and Eabs in summer than in winter. In winter a high diurnal variability in MrBC (Eabs) with higher (lower) values in the middle of the day was linked to the injection of rBC originating from the PBL. On the contrary, in summer, MrBC showed no diurnal variation despite more frequent PBL conditions, implying that MrBC fluctuations are rather dominated by regional and long-range transport in the FT. Combining the ΔMrBC/ΔCO ratio with air mass transport analysis, we observed additional sources from biomass burning in summer leading to an increase in MrBC and Eabs. The diurnal pattern of Eabs in summer was opposite to that observed in winter with maximum values of ∼2.9 observed at midday. We suggest that this daily variation may result from a photochemical process driving the rBC mixing state rather than a change in BC emission sources. Such direct 2-year observations of BC properties provide quantitative constraints for both regional and global climate models and have the potential to close the gap between model-predicted and observed effects of BC on the regional radiation budget and climate. The results demonstrate the complex influence of BC emission sources, transport pathways, atmospheric dynamics and chemical reactivity in driving the light absorption of BC.

Gas-Selective Catalytic Regulation by a Newly Identified Globin-Coupled Sensor Phosphodiesterase Containing an HD-GYP Domain from the Human Pathogen Vibrio fluvialis.

Globin-coupled sensors constitute an important family of heme-based gas sensors, an emerging class of heme proteins. In this study, we have identified and characterized a globin-coupled sensor phosphodiesterase containing an HD-GYP domain (GCS-HD-GYP) from the human pathogen Vibrio fluvialis, which is an emerging foodborne pathogen of increasing public health concern. The amino acid sequence encoded by the AL536_01530 gene from V. fluvialis indicated the presence of an N-terminal globin domain and a C-terminal HD-GYP domain, with HD-GYP domains shown previously to display phosphodiesterase activity toward bis(3',5')-cyclic dimeric guanosine monophosphate (c-di-GMP), a bacterial second messenger that regulates numerous important physiological functions in bacteria, including in bacterial pathogens. Optical absorption spectral properties of GCS-HD-GYP were found to be similar to those of myoglobin and hemoglobin and of other bacterial globin-coupled sensors. The binding of O2 to the Fe(II) heme iron complex of GCS-HD-GYP promoted the catalysis of the hydrolysis of c-di-GMP to its linearized product, 5'-phosphoguanylyl-(3',5')-guanosine (pGpG), whereas CO and NO binding did not enhance the catalysis, indicating a strict discrimination of these gaseous ligands. These results shed new light on the molecular mechanism of gas-selective catalytic regulation by globin-coupled sensors, with these advances apt to lead to a better understanding of the family of globin-coupled sensors, a still growing family of heme-based gas sensors. In addition, given the importance of c-di-GMP in infection and virulence, our results suggested that GCS-HD-GYP could play an important role in the ability of V. fluvialis to sense O2 and NO in the context of host-pathogen interactions.

Investigation on nonlinear absorption and optical limiting properties of Tm:YLF crystals

Nonlinear optical limiting has recently attracted significant attention, thanks to the continuous development of laser technology. In order to explore more potential functional materials, the spectral and nonlinear optical properties of yttrium lithium fluoride doped with thulium (Tm:YLF) crystals are reported. Absorption and emission spectra of Tm:YLF are measured, and the absorption peaks correspond to the energy transition of Tm3+. Nonlinear absorption measurements are performed on crystals with different thulium doping concentrations (2.0 %, 2.5 %, and 3.0 %). The Z-scan results indicate the presence of two-photon absorption processes at 1064 nm pulse laser. Additionally, we measured the nonlinear transmittance of Tm:YLF crystals with various thulium doping concentrations and lengths to evaluate their nonlinear optical limiting performance. For the 2.5 % doped Tm:YLF crystal with 20 mm length, the maximum transmittance at low laser intensity is 73.9 %, and the minimum transmittance at high laser intensity is 38.1 %. These experimental results suggest that Tm:YLF crystals may have potential as solid-state nonlinear optical limiting materials.

Spectral, structural, mechanical, linear, and nonlinear optical properties of L-cysteine hydrochloride monohydrate magnesium sulphate (LCHMS) single crystals synthesized by slow evaporation method

Spectral, structural, mechanical, linear, and nonlinear optical properties of L-cysteine hydrochloride monohydrate magnesium sulphate (LCHMS) single crystals synthesized by slow evaporation method

Investigation on growth, spectral, hardness, piezoelectric, contact angle, optical stress and nonlinear optical properties of acid blue 22 dye on ADP single crystals

Reclusive single crystals of ammonium dihydrogen phosphate (ADP) and 0.1[Formula: see text]mol.% Acid Blue 22 dye-incorporated ADP were harvested by using a standard slow cooling mechanism. The skeletal framework of the anisotropic materials was analyzed by using single crystal X-ray diffraction cram. The powder X-ray diffraction examines the phase growth and incorporation of substituents in the crystalline matrices. The incorporation of additives in the system was examined by employing Fourier Transform Infrared Spectroscopy. The analysis of vibrational bands gives insights into the incorporation of additives in ADP crystal system. The transmission window of the specimen and optical bandgap of the given material were analyzed by using UV–Vis spectroscopic analysis. The incorporation of additives to parent crystals was examined by using Scanning Electron Microscope. The quantification of elements in the grown specimen was investigated by using Energy Dispersive X-ray spectroscopy. The mechanical rigidity of the material was inspected by using Vickers microhardness analysis. The piezoelectric charge coefficient of dye-incorporated ADP is higher than pristine ADP. The wettability of the material was identified by contact angle measurements. The optical stress was identified by employing photoelastic measurements. The second- and third-order nonlinear optical properties of pristine and dye-incorporated ADP crystals were investigated by using Kurtz–Perry powder technique and Z-scan technique.