Optical Absorption Measurements Research Articles

The broad-spectrum biocide triclosan trigonal crystal: Experimental and DFT-calculated structural, electronic and optical properties

Triclosan, a member of the broad-spectrum biocide class, has seen widespread usage in various household and healthcare-related products worldwide over the past 35 years. However, its extensive use has raised concerns regarding health and environmental impacts. Notably, there is a notable gap in our understanding of the solid-state properties of triclosan, encompassing both experimental aspects, such as optical absorption, and theoretical insights. Expanding upon the established trigonal crystal structure of triclosan, this study employs experimental techniques including X-ray and photoacoustic-based optical absorption, alongside density functional theory (DFT) calculations, to elucidate its structural, electronic, and optical characteristics. Employing the generalized gradient approximation (GGA) DFT exchange-correlation functional and accounting for dispersion effects, optimal lattice parameters were determined with small deviations from experimental measurements (<∼2.2%). The calculations predict that the triclosan trigonal crystal has very close direct band gaps of about 3.44 eV, almost identical to the value of 3.45 eV derived from photoacoustic optical absorption measurements. Analysis of the calculated optical absorption and complex dielectric function underscores the optical isotropy of solid state triclosan. Furthermore, effective mass computations, in conjunction with the band gap results, suggest that triclosan displays electronic characteristics akin to those of a wide direct gap semiconductor.

Optical Characterization of Hydrogel and Silicone Hydrogel Soft Contact Lenses

Contact lenses are biomaterials that have emerged as an alternative to glasses in correcting vision defects. In this study, commercial nesofilcon A (hydrogel-Hy) and delefilcon A (silicone hydrogel-SiHy) daily disposable soft contact lenses were optically examined using UV-visible light spectroscopy. Optical absorption and transmittance measurements of the lenses were taken with a UV-visible spectrophotometer, and their properties of blocking the harmful part of the radiation to the eye and transmitting the harmless part were investigated. From the absorption spectrum, it was seen that the nesofilcon A lens absorbed ultraviolet light better. From the optical absorption coefficient spectra of nesofilcon A and delefilcon A lenses, the absorption edges were obtained as 386 and 325 nm, and the optical band gap values were 3.37 and 3.98 eV, respectively. Additionally, the refractive index profiles of the lenses were plotted. The refractive indices of the lenses at 550 nm wavelength were calculated as 1.55 and 1.77 for nesofilcon A and delefilcon A, respectively. While the delefilcon A lens transmitted visible light well, the nesofilcon A lens blocked UV light better and its refractive index was determined to be closer to the 1.40 the value specified by the manufacturer.

Systematic investigation of the influence of magnetic and non-magnetic ion substitutions in BiFeO3 under similar internal chemical pressure

Polycrystalline Bi1-xRxFeO3 (RHo and Y, x = 0.00, 0.05 and 0.10) compounds were prepared to perform a systematic investigation of the role of chemical nature and effect of internal chemical pressure on the structural, microstructural, magnetic, electric, ferroelectric and optical properties of the compounds. Structural analysis revealed that lattice distortions observed in Ho and Y-substituted compounds were not the same. The lattice parameters were larger in the case of the Y-substitution compared to the Ho-substituted counterpart. Scanning electron micrographs confirmed the formation of dense, well-connected grains exhibiting a reduction in size with increasing substitution. The magnetic properties of BiFeO3 were enhanced through the suppression of the spin structure with the substitution. The substitution of magnetic (Ho3+) ions led to an improvement in remanent magnetization and coercive field, whereas the substitution of non-magnetic (Y3+) ions resulted in enhanced maximum magnetization with negligible coercive field at room temperature. The ferroelectric measurements evidenced that both remanent polarization and coercive fields improved in substituted compounds, attributed to a decrease in charge carriers. Furthermore, the Y3+ ion substitution positively influenced ferroelectric properties by reducing leakage currents compared to the Ho3+ ion substitution. The optical absorption measurements indicated a decrease in the energy band gap of BiFeO3 with substitution, implying alterations in the material's optical characteristics. The ac conductivity studies demonstrated a discernible reduction in the conductivity of the substituted compounds. Specifically, Ho-substitution exhibited a more pronounced magnitude in the decline in conductivity relative to Y-substitution. This outcome signifies the potential efficacy of Ho-substitution in exerting control over the insulating characteristics of the compounds.

3D Lead-Organoselenide-Halide Perovskites and their Mixed-Chalcogenide and Mixed-Halide Alloys.

We incorporate Se into the 3D halide perovskite framework using the zwitterionic ligand: SeCYS (+NH3(CH2)2Se-), which occupies both the X- and A+ sites in the prototypical ABX3 perovskite. The new organoselenide-halide perovskites: (SeCYS)PbX2 (X = Cl, Br) expand upon the recently discovered organosulfide-halide perovskites. Single-crystal X-ray diffraction and pair distribution function analysis reveal the average structures of the organoselenide-halide perovskites, whereas the local lead coordination environments and their distributions were probed through solid-state 77Se and 207Pb NMR, complemented by theoretical simulations. Density functional theory calculations illustrate that the band structures of (SeCYS)PbX2 largely resemble those of their S analogs, with similar band dispersion patterns, yet with a considerable bandgap decrease. Optical absorbance measurements indeed show bandgaps of 2.07 and 1.86 eV for (SeCYS)PbX2 with X = Cl and Br, respectively. We further demonstrate routes to alloying the halides (Cl, Br) and chalcogenides (S, Se) continuously tuning the bandgap from 1.86 to 2.31 eV-straddling the ideal range for tandem solar cells or visible-light photocatalysis. The comprehensive description of the average and local structures, and how they can fine-tune the bandgap and potential trap states, respectively, establishes the foundation for understanding this new perovskite family, which combines solid-state and organo-main-group chemistry.

Exploring the denaturations in cancer and non-cancer DNA molecules by optical absorption, thermal, and electric measurements: A case study

In this article, we carried out the temperature dependent UV-Visible (UV-Vis) spectroscopy, differential scanning calorimetry (DSC), and electrical studies for normal and cancerous (glioma) DNA samples of single patient. Based on this method, we were able to monitor the denaturation process and thermal stability in these molecules. From the temperature dependent optical absorption data, we calculated various optical parameters for these two types of samples. The optical band gap of these samples were also estimated and discussed as per the experimental conditions. The various optical parameters calculated indicate that mutated (tumor) DNA is less stable than the normal one. From the DSC data, clear melting peaks were observed for the tumor and normal samples. Also various thermodynamic parameters like change in enthalpy (ΔH), entropy (ΔS), and specific heat (Cp) were estimated. From the thermal study, it seems that the tumor DNA is less stable. Further from the electrical or current-voltage (I-V) characteristics data, the resistance for normal DNA decreases with temperature. But for tumor sample, it show anomalous behavior (like decreasing and then increasing trend) with temperature. For electrical transport, small polaron hopping could be the possible transport mechanism in the current sample. Here from these studies, the tumor sample seems more disordered, and structural fluctuations due to the speculated structure could be the best reason for this behavior. If such kind of molecular (at nano scale range) studied are done more vividly, then these calculated parameters of the molecule could be explored for further confirmation/diagnostics of the diseases in addition to clinical investigations.

New lead-freeIodoantimonatehalide semiconductor: Synthesis, Structural characterization, DFT calculations, Hirshfeld surface, Thermal behavior, vibrational and optical properties

Hybrid metal halides have captured broad interest in the lighting and display fields because of their unique electronic structures and splendid broadband emission properties. Organic chiral building blocks can control light, charge, and spin interconversion in hybrid crystalline semiconductors with metal-halide.Based on the chiral organic molecules(S)-1-phenylethylamine, we synthesized new chiral antimony halidewith zero-dimensional structure((S)-C8H12N)4Sb2I10. Atroom temperature, the title compound is crystallized in the monoclinic P21with Z = 2 and the following unit cell dimensions: a = 12.69129 (15) Å, b = 14.96770 (15) Å, c = 13.91397 (16) Å, and β = 92.2735 (11)°.The crystal structure of this compound is composed of two crystallographically independent [Sb2I10]4- unit and four (S)-1-phenylethylammonium per unit cell. The crystal packing is governed by NH....I hydrogen bonds.Intermolecular interactions seen in the grown single crystal are studied by Hirshfeld surface and 2-D fingerprint plot.In addition to study the weak interaction a visualized approach known as RDG has been carried out.The recorded infrared IR and Raman studies confirm vibrational modes for organic and inorganic groups at room temperature in the 500–4000 cm−1 and 50–4000 cm−1 frequency regions, respectively.The optimized molecular structure and vibrational frequencies were calculated by the Density Functional Theory (DFT) method using the B3LYP level employing a LANL2DZbasis set.The title compound reveals thermal stability up to 190 °C.The opticalabsorption measurement confirms the semiconductor nature with a band gap of around 3.74 eV. The frontier molecular orbital analysis HOMO-LUMOof molecule were studied.

Facile one-pot synthesis and characterization of ZnSe/HPMC nanocomposites

Herein, we report the facile synthesis of ZnSe/HPMC (Hydroxypropyl Methyl Cellulose) nanocomposites by in-situ method. The biodegradable HPMC polymer acts as capping molecule as well as polymer matrix. The optical and structural properties of ZnSe/HPMC nanocomposites were studied by optical absorption, photoluminescence (PL) spectroscopy, FTIR, XRD and TEM measurements. Size of the ZnSe nanoparticles was tuned by controlling the pH of the reaction. As prepared ZnSe nanoparticles were spherical in shape, homogeneously distributed in the polymer and XRD patterns exhibit face centred cubic phase. The present method is a novel approach for the synthesis of ZnSe nanoparticles using HPMC as a capping molecule as well as matrix to develop nanocomposite.

Self‐Assembly of MnS Shell on CdTe Nanoparticles Induced by Thermohydrolysis: Synthesis and Characterization

Herein, CdTe/MnS core/shell nanoparticles dispersed in an aqueous solution have been synthesized. The formation of MnS semiconductor shell occurs by spontaneous self‐assembly. This process is activated by thermal hydrolysis that removes the excess of thiol and releases S2− ions. In this process, Mn2+ ions on the surface of the CdTe nanoparticles bind to S2− ions to produce a fine semiconducting layer of MnS. Measurements of Raman spectroscopy, optical absorption, and electrochemical measurements are performed. The Raman spectrum shows CdTe characteristic bands at 141 and 163 cm−1. Bands at 221 and 444 cm−1 are associated with the MnS structure. Cyclic voltammetry and differential pulse voltammetry are used to estimate the electrochemical gap at ≈2.47 eV. Absorption optical measurements show tree absorption bands. A broad band between 460 and 520 nm is associated with the first transition in CdTe nanoparticle. The absorption spectrum reveals an optical gap in the range of 2.41–2.33 eV for all the refluxed samples. These values are consistent with those obtained with the electrochemical measurements. The results evidence the formation of a core–shell semiconducting nanostructure made of CdTe nanoparticles coated with a spontaneously self‐assembled thin layer of MnS nanoparticles.

Self-assembled tin(IV) organic-inorganic hybrids: Synthesis, spectral, structural, and Hirshfeld surface analysis of bis(thiomorpholinium) hexahalostannate(IV)

At room temperature, organic-inorganic hybrids, including bis(thiomorpholinium) hexachlorostannate(IV) hydrate (1) and bis(thiomorpholinium) hexabromostannate(IV) (2), were synthesized from thiomorpholinium chloride/bromide. The hybrids underwent characterization using, IR, elemental, NMR, TGA, DRS and PL spectroscopy, along with single-crystal X-ray diffraction (SCXRD). SCXRD confirms compounds are crystallized in a monoclinic system exhibiting centrosymmetric space groups (C2/candP21/c for (1) and (2)). The SCXRD structures of the hybrids unveiled significant H-bonded interactions between the thiomorpholinium cation and the SnCl62-/SnBr62- anions. At room temperature, optical absorption measurements revealed band gaps of 3.91 eV for (1) and 3.00 eV for (2).TGA confirmed the proposed formulas of the compounds.BVS calculations conducted on SnCl62- and SnBr62- anions yielded values of 4.01 and 3.94, respectively. Fingerprint plots were employed to identify and quantify the proportion of hydrogen bonding interactions.

Temperature dependence of the near infrared absorption spectrum of single-wall carbon nanotubes dispersed by sodium dodecyl sulfate in aqueous solution: experiments and molecular dynamics study.

Single-wall carbon nanotubes (SWCNT) dispersed in water with the help of sodium dodecyl sulfate (SDS) surfactants exhibit a temperature dependent near infrared (NIR) exciton spectrum. Due to their biocompatibility and NIR spectrum falling within the transparent window for biological tissue, SWCNTs hold potential for sensing temperature inside cells. Here, we seek to elucidate the mechanism responsible for this temperature dependence, focusing on changes in the water coverage of the SWCNT as the surfactant structure changes with temperature. We compare optical absorption spectra in the UV-Vis-IR range and fully atomistic molecular dynamics (MD) simulations. The observed temperature dependence of the spectra for various SWCNTs may be attributed to changes in the dielectric environment and its impact on excitons. MD simulations reveal that the adsorbed SDS molecules effectively shield the SWCNT, with ~ 70% of water molecules removed from the first two adlayers; this coverage shows a modest temperature dependence. Although we are not able to directly demonstrate how this influences the NIR spectrum, this represents a potential pathway given the strong influence of the water environment on the excitons in SWCNTs. Optical absorption measurements were carried out in the UV-Vis-NIR range using a Varian Cary 5000 spectrophotometer in a temperature-controlled environment. PeakFit™ v. 4.06 was used as peak-fitting program in the spectral range 900-1400nm (890-1380meV) as a function of the temperature. Fully atomistic molecular dynamics simulations were conducted using the NAMD2 package. The CHARMM force field comprising two-body bond stretching, three-body angle deformation, four-body dihedral angle deformation, and nonbonded interactions (electrostatic and Lennard-Jones 6-16 potentials) was employed.

Exploring the structural, optical and photoluminescence of novel terbium-doped barium borosilicate glasses for high-performance technologies

The production process involved the use of the melt-quenching approach to produce a series of barium borosilicate glasses with the specific chemical formula 55B2O3+(26-x)BaO+12SiO2+7Na2O + xTb4O7, where x = 0, 0.5, 1, 2, and 3 mol%. X-ray diffraction (XRD), Raman spectroscopy, optical absorption, and photoluminescence spectra measurement were used to examine the prepared samples. X-ray diffraction revealed the non-crystalline character of the assembled samples. The Raman spectroscopy revealed that the incorporation of Tb4O7 into borosilicate glasses induced alterations in their structure. As the doping of Tb3+ ions increases, the density and molar volume of the glasses under investigation increase. Furthermore, the ion concentration and field strength increase while the polaron radius and inter-ionic distance decrease. The glass optical absorption spectra showed five peaks in the wavelength range from 300 nm to 2000 nm: 5L10, 5D3, 5D4, 7F(0, 1, 2), and 7F3, attributed to Tb3+ ion electronic transitions. In addition, optical parameters like optical energy gap, Urbach energy, refractive index, molar refractive index, reflection loss, electronic polarizability, and optical transmission coefficient were computed. Terbium-doped borosilicate glasses had a decreased optical energy gap and an improved refractive index. Photoluminescence spectra were excited at 325 nm and showed five peaks in the range of 400–750 nm. Photoluminescence (PL) emission spectra exhibit distinct peaks in the visible range.

Impact of electronic correlation on strong laser-induced bound-state transitions

Electron correlation (EC) plays a crucial role in all multi-electron systems and dynamic processes. In this work, we focus on strong laser-induced bound-bound transitions (BBT), which are fundamental to optical absorption measurements. We use the helium atom, the simplest two-electron system, as our test case, utilizing the ab initio code package HeTDSE. We examined the bound state energy levels, transition dipole moments (TDMs), and the dynamics of strong laser-induced BBT, both with and without considering EC. Our results indicate that EC significantly impacts the energy levels of the bound states and the TDMs. These effects collectively influence the transition dynamics of the excited states. Although EC does not alter the quantum transition pathways between resonance states, it generally increases the probability of resonance transitions in most cases. Our findings provide a quantitative description of EC in laser-induced BBT.

3D Lead‐Organoselenide‐Halide Perovskites and their Mixed‐Chalcogenide and Mixed‐Halide Alloys

We incorporate Se into the 3D halide perovskite framework using the zwitterionic ligand: SeCYS (+NH3(CH2)2Se−), which occupies both the X− and A+ sites in the prototypical ABX3 perovskite. The new organoselenide‐halide perovskites: (SeCYS)PbX2 (X = Cl, Br) expand upon the recently discovered organosulfide‐halide perovskites. Single‐crystal X‐ray diffraction and pair distribution function analysis reveal the average structures of the organoselenide‐halide perovskites, whereas the local lead coordination environments and their distributions were probed through solid‐state 77Se and 207Pb NMR, complemented by theoretical simulations. Density functional theory calculations illustrate that the band structures of (SeCYS)PbX2 largely resemble those of their S analogs, with similar band dispersion patterns, yet with a considerable bandgap decrease. Optical absorbance measurements indeed show bandgaps of 2.07 and 1.86 eV for (SeCYS)PbX2 with X = Cl and Br, respectively. We further demonstrate routes to alloying the halides (Cl, Br) and chalcogenides (S, Se) continuously tuning the bandgap from 1.86 to 2.31 eV—straddling the ideal range for tandem solar cells or visible‐light photocatalysis. The comprehensive description of the average and local structures, and how they can fine‐tune the bandgap and potential trap states, respectively, establishes the foundation for understanding this new perovskite family, which combines solid‐state and organo‐main‐group chemistry.

Structural, optical, and electrical properties of multi-component P-type oxide-semiconductor Cu-Mn-Sn-O thin films

P-type oxide semiconductors have attracted significant attention as conducting channel layers due to their wide applications in electronic devices. In this study, multi-component oxide-semiconductor Cu1–2xMnxSnxO thin films with x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, and 0.33 were prepared on glass substrates using a solution process accompanied by a spin-coating technique. A phase transition between the cupric oxide monoclinic structure and the rock salt structure was observed with increasing concentrations of Mn and Sn, while the concentration of Cu simultaneously decreased in the precursors. The crystallite size decreased throughout the samples, reaching a minimum value of 9.8 nm at an equimolar ratio. Scanning electron microscopy further confirmed this downward trend and indicated an improvement in the quality of the film surfaces. According to the optical absorption measurements, the bandgap energy ranged from 2.68 to 3.44 eV. Interestingly, the sheet resistance of Cu1–2xMnxSnxO films dropped sharply from 5.24 kΩ/sq for CuO to 0.034 kΩ/sq for the film with a molar ratio of Cu:Mn:Sn being 34:33:33.

Electronic states near surfaces and interfaces of β-Ga2O3 and κ-Ga2O3 epilayers investigated by surface photovoltage spectroscopy, photoconductivity and optical absorption

Transient surface photovoltage (SPV) spectroscopy, optical absorption, and photoconductivity (PC) were applied to study electronic transitions in (-201) β-Ga2O3 and (001) κ-Ga2O3 epitaxial layers on c-plane sapphire substrates. SPV signals were distinguished for charge separation near the surface and near the layer/substrate interface. The bandgaps of β-Ga2O3 and κ-Ga2O3 epitaxial layers were found to be, respectively, about 4.75 and 4.79 eV from optical absorption measurements, about 4.8 and 4.9 eV from PC, and 4.65 and 4.9 (near the surface) from SPV measurements. Near the κ-Ga2O3 layer/substrate interface SPV instead gives a value of 4.75 eV, possibly related to the presence of an interlayer. Defect-related transitions with onset energies at about 4.5, 4.1, and 3.5 eV were observed along the whole β-Ga2O3 layer cross-section. In contrast, defects related to different transitions were differently distributed in κ-Ga2O3 epitaxial layers: transitions setting on at about 4.3 eV originate from defects uniformly distributed across the layer, while transitions starting at 2.4 eV and 1.7 eV were respectively connected with defects located near the surface or near the layer/substrate interface. The PC measurements at photo-excitation energy above the bandgap indicated that defect densities and recombination losses were much larger in κ-Ga2O3 than in β-Ga2O3.

Structural, optical and thermoluminescence properties of amazonite

This study presents an analysis of the structural and thermoluminescence properties of amazonite, a feldspar species. The characterization was done using X-ray diffraction (XRD), X-ray fluorescence (XRF), optical spectroscopy, and vibrational spectroscopies such as Raman and Fourier Transform Infrared (FTIR). The sample exhibits a partial (Al, Si) ordenation, and contains an albite phase in addition to microcline. FTIR and Raman indicated the presence of water and OH– vibration modes. Optical absorption measurements highlighted the influence of the hydroxyl groups as catalyst for Pb transitions, contributing to the coloration of amazonite. Thermoluminescence (TL) studies were performed within a dose range from 0.1 to 10 Gy using a built-in beta source (90Sr/90Y; delivering 10 mGy/s), showing seven TL glow peaks based on non-first kinetic order. The sample exhibited a linear dose–response, with TL signals proving to be both repeatable and reproducible (CV ∼ 2%). Fading analysis showed the first two TL peaks disappear after 16 days of dark storage. Thermal quenching behavior was investigated under various heating rates, demonstrating a decrease in luminescence efficiency with increasing heating rates. Additionally, the activation energies were determined using different methods, and the amazonite TL glow curve presented activation energies values within 0.7 to 2 eV.

2D hybrid organic-inorganic perovskite displaying narrow-band violet-blue photoluminescence

Hybrid organic-inorganic perovskites represent a drastically expanding class of solid-state semiconducting materials for optoelectronics and photovoltaics. Thanks to the easy chemical tunability, this class of materials can offer emitters of very wide spectral range, however, violet-blue emitting hybrid perovskites still remain underrepresented. In this paper we report on a novel two-dimensional hybrid organic-inorganic perovskite (ethylammonium)2CdBr4. Crystal structure of the reported compound is composed of infinite inorganic 2D layers that are created by [CdBr6]4- octahedra connected in corner-by-corner manner. These layers are separated by organic ethyammonium cations which create hydrogen bonds with the inorganic part. Optical absorption measurements revealed the presence of a large band gap of 4.25 eV. Importantly, this material displays narrow photoluminescence band at 388 nm (full width at half maximum is 32 nm). Chromaticity coordinates of the perovskite emission are close to NTSC blue standard. Band structure and DOS calculations show that the states close to Fermi level predominantly originate from cadmium and bromide. Thus, here we offer a facile way towards violet-blue luminophore containing simple and widely available organic cation ethylammonium.

Synthesis of ZnO and CuO–ZnO nanocomposites for photo-conducting and dielectric applications

Zinc oxide (ZnO) and its composites has garnered a tremendous attention lately due to its effective role in electronic and optoelectronic applications. The present manuscript reports the synthesis and characterization of ZnO and CuO–ZnO nanocomposites. These samples were synthesized using precipitation technique and studied for voltage-dependent dielectrics and photoconductivity properties. Structural properties were thoroughly investigated using powder X-ray diffraction (PXRD) measurements. The composite material revealed decreased crystallinity and increased strain in the material. Optical absorption measurements were recorded using UV–vis diffusion reflectance measurements and the changes in the absorbance spectrum corresponding bandgap is explored. The obtained band gap is comparatively less for the composite material when compared with prestine ZnO. Structural morphology of the synthesized materials was observed and compared and changes in the composites when compared with the ZnO. Drastic changes in the morphology is witnessed. Electrical response of these synthesized semiconductors was studied using I–V and dielectric measurements. CuO–ZnO samples show a very clear sensitivity to the voltage dependent dielectric properties compared to ZnO. The composite and ZnO are studied using I–V measurements and the light dependent I–V measurements and composite revealed photo sensitivity. Drastic change in the conductivity is witnessed inferring the material to be used in optoelectronic application. Dielectric, Impedance, dielectric loss, AC conductivity and modulus index of the materials were explored by subjecting the materials to impedance measurements. The materials were also explored with different voltages and compared. The composite material revealed drastic variations for change in the voltage and measured parameters were compared with the ZnO.

Optoelectronic properties of β-Cyclodextrin compound and doped with Na: Comparative study by experimental and DFT approaches

The chemical and physical properties of β-Cyclodextrin (β-CD) and doped with Na can be useful in drug delivery, organic solar cells and photoprotective applications. Physicochemical properties of pure β-CD and doped with Na were investigated by both density functional theory (DFT) and experimental methods. Theoretical calculations and the experimental measurements revealed that β-CD has a direct band gap of 3.44 and 4.14 eV, respectively. The optical absorption measurements indicate that band gap value decreases by Na doping to 3.09 eV. DOS spectra confirmed the stabilization of β-CD by the strong covalent bonds between C and O atoms. Obtained small effective mass of charge carriers with the high carrier mobility in β-CD show that it is a good candidate for using in the organic electronic applications. The significant isotropic behavior was observed in all optical spectra. The positive values of the real part of dielectric function confirm the dielectric nature of β-CD. Maximum dielectric polarization is observed at the ultraviolet region with the static dielectric constant of 2.03. High reflectivity at the ultraviolet region and beyond that confirm the photoprotective properties of β-CD compound against harmful solar radiations. There is a good agreement between the obtained experimental and DFT spectra. Our findings may be useful in design of new organic optoelectronic devices.

Mg/S@g-C3N4 nanosheets: A promising fluorescence sensor for selective Cu2+ detection in water

This work describes the development of a novel fluorescence sensor based on magnesium/S@g-C3N4 nanosheets for selective detection of copper (Cu2+) ions in water. Mg/S@g-C3N4 nanosheets were prepared by the polycondensation technique and investigated by X-ray diffraction (XRD), ATR-FTIR spectroscopy, scanning electron microscopy (SEM), surface area (BET), and UV–Vis optical absorption measurements. XRD and ATR-FTIR analysis showed the characteristic peaks for S@g-C3N4. The broad full width at half maximum (0.056 radians) implies a smaller crystallite size, representing smaller Mg/S@g-C3N4 sheets. SEM micrograph showed non-exfoliated nanosheets with flake-like structures. The EDS mapping confirmed the presence of magnesium, carbon, nitrogen, and sulfur throughout the nanosheets. The Mg/S@g-C3N4 nanosheets possess a high surface area of 40 m2/g and mesopores within the nanosheets, with a size of 1.57 nm. The band gap of the Mg/S@g-C3N4 nanosheet was estimated to be 3.0 eV. The sensor exhibits a strong quenching response towards Cu2+ ions, with a decrease in fluorescence intensity as the concentration of Cu2+ increased from 1 μM to 20 μM. The Stern-Volmer quenching constant (KSV) showed a relatively high value of 185053 M−1. The estimated value of LOD by the Mg/S@g-C3N4 sensor for Cu2+ was 16.2 nM. The sensor offered high sensitivity and selectivity for Cu2+ detection over other heavy metals.