Optical Properties Of Materials Research Articles

Field Manipulation of Band Properties in Infrared Spectra of Thin Films

This comprehensive optical study analyzes field manipulations of bands in infrared (IR) spectra of thin films and functional surfaces for varying measurement and sample conditions. Band variations related to the materials dielectric functions, the measurement geometry, the film thickness as well as the direction dependence of the probing electromagnetic fields are demonstrated. Examples are discussed for isotropic polymer films (≈200 nm polymethylmethacrylate [PMMA]) on gold and silicon as well as an anisotropic hydrogen monolayer on a Si(111) surface, characterized by IR–attenuated total reflection, IR microscopy, and incidence‐angle‐dependent IR polarimetry. Even for fixed optical material properties, significant manipulations of band frequency and shape (shifts up to ≈14 cm−1 for PMMA, up to ≈3 cm−1 for H–Si) occur in not only polarization‐dependent but also unpolarized spectra. The shown data underline that polarimetric measurements and optical analyses are essential for a detailed interpretation of band shapes.

Investigating Electronic, Optical, Thermodynamic, and Thermoelectric Properties of SrO and SrO2 Phases: A Density Functional Theory Approach.

The significance of strontium oxide (SrO) and strontium peroxide (SrO2) is currently being investigated as one of the countless potential uses for green energy. However, few studies have examined the distinctive properties of several phases of SrO and SrO2. In order to fill this research gap, we have conducted a study on their various properties through "density functional theory (DFT)" under ideal conditions. This includes the study of electronic, optical, thermodynamic, and thermoelectric properties of the above-mentioned materials. For this study, the "Quantum Espresso" tool in DFT using Perdew-Burke-Ernzerhof-generalized-gradient approximation (PBE-GGA) as the exchange-correlation functional and "Optimized Norm-Conserving Vanderbilt (ONCV)" as the pseudopotential has been used. The face-centered cubic (FCC), body-centered cubic (BCC), hexagonal-1, and hexagonal-2 phases of SrO and the tetragonal and orthorhombic phases of SrO2 have been selected for the aforesaid study, for which some structural information has already been available. During this study, the energy band gap as an electronic property; the dielectric constant, refractive index, absorption coefficient, reflectivity, and energy loss function as optical properties; entropy, heat capacity, Debye temperature, and Debye sound velocity as thermodynamic properties; and the Seebeck coefficient, thermal conductivity, electrical conductivity, and figure of merit as thermoelectric properties have been investigated. In addition, phonon dispersion curves and formation energies have been used to confirm the dynamical stability and thermodynamic stability, respectively, for all of the materials mentioned above. The curve showed that the FCC, hexagonal-1, and hexagonal-2 phases of "SrO" are dynamically stable. These materials have good optoelectronic properties and can be used in ultraviolet sensors due to their intermediate band gap and highest material response in the ultraviolet range. In terms of thermoelectric property, the maximum value of "figure of merit" for the above material has been achieved up to 0.5. Satisfactory agreement has been found between the current findings and the known theoretical and experimental findings.

Effect of Cu-doping on the optical properties of quantum dot materials in group II-VI using density functional theory approach

Effect of Cu-doping on the optical properties of quantum dot materials in group II-VI using density functional theory approach

Dimensionality Engineering of Lead Organic Chalcogenide Semiconductors.

Two-dimensional (2D) metal organic chalcogenides (MOCs) such as silver phenylselenolate (AgSePh) have emerged as a new class of 2D materials due to their unique optical properties. However, these materials typically exhibit large band gaps, and their elemental and structural versatility remain significantly limited. In this work, we synthesize a new family of 2D lead organic chalcogenide (LOC) materials with excellent structural and dimensionality tunability by designing the bonding ability of the organic molecules and the stereochemical activity of the Pb lone pair. The introduction of electron-donating substituents on the benzenethiol ligands results in a series of LOCs that transition from 1D to 2D, featuring reduced band gaps (down to 1.7 eV), broadband emission, and strong electron-phonon coupling. We demonstrated a prototypical single crystal photodetector with 2D LOC that showed the dimensionality engineering on the transport property of LOC semiconductors. This study paves the way for further development of the synthesis and optical properties of novel organic-inorganic hybrid 2D materials.

Substrate-tuned dielectric screening effect on optical properties of monolayer MoSe2

Grasping the intricate mechanisms for the influences of dielectric screening from diverse substrates on the optical properties of ultra-thin two-dimensional materials is crucial for related device design. This study investigates the substrate impacts on the optical properties of monolayer MoSe2 by combining the spectroscopic ellipsometry (SE) and first-principle calculations. Featured absorption peaks of monolayer MoSe2 on substrates of quartz, silicon, and sapphire are meticulously analyzed via critical point (CP) analysis on the dielectric functions determined by SE. Results indicate that variation in substrates induces notable shifts in energy positions of the absorption peaks due to different dielectric screening effects. The study further uncovers electron transfer from silicon substrate to monolayer MoSe2, leading to alterations in the band structure. By integrating CP analysis with first-principle calculations, we gain a comprehensive understanding of the optical transitions corresponding to CPs in the monolayer MoSe2 on various substrates. This establishes that the energy shifts of CPs regulated by substrate-induced dielectric screening are highly correlated with the positions of their corresponding optical transitions in momentum space. These findings underscore the pivotal role of substrate selection in customizing the optical properties of two-dimensional materials, providing valuable insights for the design and optimization of MoSe2-based photonic devices.

Two UV organic-inorganic hybrid antimony-based materials with superior optical performance derived from cation-anion synergetic interactions

Finding suitable strategies to effectively enhance the optical properties of materials are the goal being pursued by researchers. Herein, cation-anion synergetic interactions strategy was proposed to develop two novel organic-inorganic hybrid antimony-based optical materials, (C3H5N2)SbF2SO4 (I) and (C5H6N)SbF2SO4 (II), which were obtained by introducing Sb3+cation containing stereochemically active lone-pair (SCALP) and organic π-conjugated cations into sulphate system. The synergistic interactions of the organic π-conjugated cations, the inorganic [SbO2F2]3− seesaw anions and the [SO4]2− distorted tetrahedra anions make their ultraviolet (UV) absorption edges approach 297 and 283 nm, respectively, and raise their birefringence up to 0.193@546 nm and 0.179@546 nm, respectively. Interestingly, although the two compounds have the same stoichiometric ratio and similar one-dimensional (1D) chain structure, they show opposite macroscopic symmetry, where the NCS compound (II) exhibits a large second-harmonic generation (SHG) response (1.6 times that of KH2PO4). The two reported compounds are found to be promising UV optical materials in the experimental tests.

Donor-π-Acceptor Porphyrin-Assisted Bifunctional Defect Passivation for Enhanced Temporal Domain-/Wavelength-Dependent Nonlinear Absorption Properties in Perovskite Films.

Perovskite layer defects are a primary inhibiting factor for their optical nonlinearity, which restricts their use in nonlinear photonics devices. Nevertheless, due to the variety of defect types, the passivation and repair of these defects remain challenging. Herein, a novel bifunctional passivation strategy was proposed, and the porphyrin with a donor-π-acceptor structure was designed to bifunctionally repair perovskite defects by linking different types of functional groups via acetylenic π-conjugated linkage bridges on both sides, thus improving the nonlinear optical (NLO) absorption properties of porphyrin-perovskite hybrid materials. Research results indicate that the amino and carboxyl groups of porphyrins endow the ability to bifunctionally passivate charged defects via effective coordination interactions. The nonlinear absorption properties of all porphyrin-passivated MAPbI3 films were remarkably enhanced compared to that of the MAPbI3 film across multiple wavelengths and temporal domains. Particularly, the Por3-passivated perovskite film (MAPbI3/Por3) exhibited optimized strongest NLO performance, including reverse saturable absorption (RSA) under 800 nm femtosecond (fs) and 1064 nm nanosecond (ns) laser irradiations, as well as saturable absorption (SA) with 515 and 532 nm ns laser excitations. The value of the NLO absorption coefficient (β = 266.23 cm GW-1) is 1 order of magnitude higher than that of the pristine perovskite film (β = 12.93 cm GW-1), also outperforming other porphyrin-passivated perovskite films and some reported materials. The bifunctional passivation mechanism of porphyrin not only intensifies the perovskite's photoinduced ground-state dipole moment in the two-photon absorption (TPA) process and the free carrier absorption ability to deepen the RSA properties under 800 nm fs and 1064 nm ns lasers, respectively, but also enables the improvement of SA responses under 515 nm fs and 532 nm ns lasers by expediting the Pauli blocking effect of perovskite. Our study offers a viable paradigm, which aims at exploiting high-performance NLO perovskite materials across wide spectral regions and time scales.

Advances in organic–inorganic nanocomposites for cancer imaging and therapy

Abstract “All in one” organic–inorganic nanocomposites with high biocompatibility and excellent physicochemical properties have recently attracted special attention in cancer imaging and therapy. Combination of organic and inorganic materials confers the nanocomposites with superior biocompatibility and biodegradability of organic materials, as well as magnetic, mechanical, and optical properties of inorganic materials. Increased endeavors have been made to produce diverse organic–inorganic nanocomposites and investigate their potential applications in cancer treatment. Thus, a systematic review of research progresses of diverse organic–inorganic nanocomposites in cancer imaging and therapy is indispensable. Following a brief overview of nanocomposites synthesis, classification, and functionalization, the current review is focused on comprehensively summarizing representatives of both organic–inorganic nanoscale nanocomposites (including organic-silica, organic-carbon, organic-quantum dots, organic-platinum family metals, organic-gold, organic metal oxides, and other nanocomposites) and organic–inorganic molecular nanocomposites (including metal-organic frameworks, organosilica nanoparticles, and amorphous metal coordination polymer particles), and further analyzing their working mechanism in cancer imaging and therapy. Finally, the challenges and future perspectives of organic–inorganic nanocomposites are addressed for promoting their developments and clinical application in cancer treatment.

Synthesis and Characterization of PANI/ZnFe2O4 nRs with Different Doping Concentrations for Potential Applications in Various Fields

The wide-ranging potential of polyaniline (PANI) composites in energy storage, electrochemical, sensing, and electromagnetic shielding applications emphasizes researchers to improve its properties. Here, the doping of ZnFe2O4 nRs by 1, 3, and 5 wt. % within polyaniline has been done. Then, we characterize the doped material using techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR) to verify the successful incorporation of polyaniline onto the nRs. TGA showed that doping of PANI with ZnFe2O4 nRs enhanced the interfacial interactions between the two components. This provided a more stable matrix structure and enhanced the thermal stability of the composite. The transmission of light has been increased by about 18% due to the increase in crystallinity accompanied by ZnFe2O4 doping. As the ZnFe2O4 nRs doping rose, our PANI samples’ optical band gap values slightly decreased by about 10%. In addition, it has been found that the optical characteristics such as refractive index, extension coefficient, surface, and volume energy loss function essentially showed ZnFe2O4 doping dependency. The nonlinear constants of the doped samples have increased due to the new charge carriers and altered the electronic and optical properties of the composite material. Our obtained results show that PANI@ ZnFe2O4 nRs have potential applications such as optical sensors, electrochemical, optoelectronics, and photocatalysis.

Stainability and translucency of potassium aluminum sulfate applied computer-aided design and computer-aided manufacturing materials after coffee thermocycling.

The purpose of this in vitro study was to evaluate the effect of potassium aluminum sulfate (alum) application on the stainability and translucency of computer-aided design and computer-aided manufacturing (CAD-CAM) materials after coffee thermocycling (CTC). Disk-shaped specimens (Ø10 × 1 mm; N = 200) were fabricated by using additively (Crowntec [CT] and Varseo Smile Crown Plus [VS]) and subtractively manufactured (Brilliant Crios [RCR], CEREC Block [FC], and Vita Enamic [VE]) CAD-CAM materials and polished. All specimens were randomly divided into two groups as alum applied and control (n = 10). All specimens were then subjected to CTC (10,000 cycles at 5-55°C) and color coordinates were measured at each time interval. Color differences (ΔE00 ) and relative translucency parameters (RTPs) were calculated and the data were statistically analyzed (a = 0.05). Among tested time intervals, alum applied specimens had their lowest ΔE00 after alum application (p ≤ 0.006), except for FC (p = 0.177). In addition, alum applied RCR had lower ΔE00 values than its control specimens (p = 0.029). Alum applied specimens had their lowest RTP after CTC (p < 0.001) and alum application decreased the RTP of CT (p = 0.010). CTC reduced the RTP of all materials in control groups (p < 0.001). Alum applied CT had higher RTP than its control specimens (p = 0.049). Alum application's effect on color change varied depending on the material and alum mostly resulted in clinically acceptable changes in translucency. CTC led to unacceptable color and translucency changes based on previously reported threshold values. Optical properties of CAD-CAM materials and the sustainability of these properties over time is critical for longevity. Alum may improve the color stability of reinforced composite resin when subjected to long-term coffee consumption.

Role of Micro-Architectures on Insects' Elytra Affects the Nanomechanical and Optical Properties: Inspired for Designing the Lightweight Materials

The structural coloration of insects has received significant attention in the field of nanophotonic, which has related properties with biophotonic crystals. The main focus in this study is on structural and mechanical features of wasp and beetle elytra such as Chrysidinae (the specimen of parasitoid or kleptoparasitic wasp), Rhomborhina gigantea (RG is the specimen of bettle in the family of Cetoniidae), and Chrysolina coerulans (CC is a species of beetle in the family Chrysomelidae). The nanostructures present on the surface of elytra show the optical and deformable material properties. Surface morphology has been measured by scanning electron microscopy and atomic force microscopy (AFM). The depths of the hemispherical cavities present on the elytra have been analyzed using AFM. The optical and nanomechanical properties of the beetle elytra have also been studied. To measure the reflectivity in transverse electric and TM mode, UV-visible spectroscopy has been used. The value of the average index of refraction nav is observed as 1.8 in all three species and the half-pitch of elytra's varies from 0.139-0.136 μm in CC, 0.123-0.114 μm in Chrysidinae, and 0.154-0.161 μm in RG. Nanoindentation was used to measure the modulus and hardness of the different beetle's elytra. Higher value of elastic modulus (1.72 GPa) and hardness (0.89 GPa) in RG of elytra plays a significant role in resisting force. The photonic structure exhibits optical intrinsic color mixing properties, which are used in the anticounterfeiting fields (currency and passport identification codes). The structural properties of beetle elytra would help to design the lightweight, high strength, anti-coating sensor, color-changing micro air vehicles, and novel optical materials.

First principles study of 2-(acetoxy group)benzoic acid under different extremely high-pressure environments

Based on Density Functional Theory (DFT), a first-principles study was conducted on the crystal structure, electronic structure, and optical properties of the organic material 2-(acetoxy group) benzoic acid crystal (C9H8O4) under extremely high pressure ranging from 0 to 300 GPa. The structure study revealed the significant bonding and bond breaking phenomena at pressures of 80 GPa and 270 GPa, respectively, indicating that it may induced the lattice phase transitions. The energy band analysis demonstrated that the crystal underwent a transition from a direct bandgap semiconductor at 0 GPa to an indirect bandgap semiconductor at 80 GPa, and then at 270 GPa, the crystal exhibited a metallic phase with a bandgap of 0. The density of states (DOS) provided evidence that this crystal undergo intricate phase transitions under extremely high pressure. The optical properties were further compared and analyzed. It was observed that the peak of optical absorption shifted towards higher energy regions, while the peak of photoconductivity and Loss function shifted towards the blue shift. These findings indicate that extremely high pressures can effectively modulate the structure and properties of C9H8O4 material. This research offers valuable insights for further exploration of the properties of C9H8O4 materials and their potential applications in organic optoelectronic devices.

Structural, optical, elastic, thermoelectric and thermodynamic properties of the IrMn material: A DFT study

In this work, we present a study of the structural, optical, elastic, thermoelectric and thermodynamic properties of iridium manganese (IrMn) using the code “WIEN2k” with the full potential linearized augmented plane wave (FP-LAPW) method. The lattice constants of the IrMn compound are calculated by the generalized gradient approximation with Perdew–Burke–Ernzerhof (GGA-PBE). Indeed, we have studied the magnetism exhibited by the compound IrMn. We found that the antiferromagnetic phase of this material is the most stable phase. The magnetic moment, plasma frequency, bandgap, elastic constants, and electronic and magnetic properties of this material are deduced and discussed. We have shown that the antiferromagnetic phase is the most stable with a minimum energy value of around −1034947.477[Formula: see text]eV. We optimized the [Formula: see text] ratio and found that its value is approximately [Formula: see text] 0.923133. On the other hand, the absorption and reflectivity coefficients, the optical conductivity and the dielectric tensor are studied. In addition, the thermo-electric and thermodynamic properties have been illustrated. The IrMn compound could be useful for different applications of spintronics.

Optimizing experimental parameters for orbital mapping

A new material characterization technique is emerging for the transmission electron microscope (TEM). Using electron energy-loss spectroscopy, real space mappings of the underlying electronic transitions in the sample, so called orbital maps, can be produced. Thus, unprecedented insight into the electronic orbitals responsible for most of the electrical, magnetic and optical properties of bulk materials can be gained. However, the incredibly demanding requirements on spatial as well as spectral resolution paired with the low signal-to-noise ratio severely limits the day-to-day use of this new technique. With the use of simulations, we strive to alleviate these challenges as much as possible by identifying optimal experimental parameters. In this manner, we investigate representative examples of a transition metal oxide, a material consisting entirely of light elements, and an interface between two different materials to find and compare acceptable ranges for sample thickness, acceleration voltage and electron dose for a scanning probe as well as for parallel illumination.

A fundamental study on the electronic and optical properties of graphene oxide under an external electric field

In this work, we study the impact of the external electric field [Formula: see text] on graphene oxide (GO) layer to improve and optimize its electronic and optical properties, as a result to enhance optoelectronic device technology applications. A three-dimensional [Formula: see text] applied on GO will be examined using the density functional theory (DFT). The [Formula: see text] causes significant modifications to the electronic and optical properties of GO. When increasing the [Formula: see text], a global increase is noted in the bandgap in the x- and y-directions. As for the z-direction, the bandgap energy of GO decreases for an increasing [Formula: see text]. The absorption coefficient ([Formula: see text]) peaks intensities decreased in both visible and ultraviolet (UV) ranges by the effect of the [Formula: see text] applied in the x-direction, and were increased when the [Formula: see text] is applied in the y- and z-directions. It was found that, the electronic and optical properties of GO material, could be controlled by the effects of the [Formula: see text] and by its direction.

Lorentz microscopy of optical fields

In electron microscopy, detailed insights into nanoscale optical properties of materials are gained by spontaneous inelastic scattering leading to electron-energy loss and cathodoluminescence. Stimulated scattering in the presence of external sample excitation allows for mode- and polarization-selective photon-induced near-field electron microscopy (PINEM). This process imprints a spatial phase profile inherited from the optical fields onto the wave function of the probing electrons. Here, we introduce Lorentz-PINEM for the full-field, non-invasive imaging of complex optical near fields at high spatial resolution. We use energy-filtered defocus phase-contrast imaging and iterative phase retrieval to reconstruct the phase distribution of interfering surface-bound modes on a plasmonic nanotip. Our approach is universally applicable to retrieve the spatially varying phase of nanoscale fields and topological modes.

Electron spin resonance in emerging spin-driven applications: Fundamentals and future perspectives

Spin, the intrinsic angular momentum of an electron, is increasingly being recognized as a versatile tool in the development of next-generation technologies, including quantum computing, sensing, and communication, which exploit quantum phenomena. The burgeoning theoretical understanding coupled with technological advancements have catalyzed research efforts aimed at controlling and manipulating the optical, electrical, magnetic, and thermal properties of materials through the modulation of spin states. Among the myriad of techniques available for investigating these spin-dependent properties, Electron Spin Resonance (ESR), sometimes referred to as electron paramagnetic resonance, stands out as one of the most direct and potent methods to probe electron spin dynamics irrespective of the material environment. ESR furnishes insightful data on the states of individual spins and clusters, spin coherence via relaxation time measurements, and inter-spin distances from spin–spin interaction measurements. Additionally, ESR facilitates the manipulation of spin systems by tailoring the Zeeman energy through the modulation of the external magnetic field, and critically, by the remote manipulation of spins via the application of microwave pulses at resonance frequencies. Modern ESR experimental setups are versatile and can be employed across a wide temperature spectrum—from a few Kelvin, where quantum effects are pronounced, to room temperature and beyond. This adaptability enhances the utility of ESR in investigating the spin-dependent properties in condensed matter systems. Notwithstanding the tremendous potential and advantages that ESR offers, it remains underutilized, especially when compared to inelastic neutron scattering (INS) and nuclear magnetic resonance, despite the latter being more expensive and INS being less accessible. In this review, we elucidate the fundamental principles of ESR, with an emphasis on magnetic and spin interactions in solids, and explore the potential of ESR in advancing the understanding of spin properties across a diverse array of materials science disciplines. We commence with a concise introduction to spin-related physics, followed by the application of ESR in characterizing spin systems. As such, this review aims to serve as a valuable resource for a broad audience, ranging from novices to experts, who are keen on unraveling spin phenomena and dynamics in materials science and condensed matter physics.

Cubic Nonlinearity of Graphene-Oxide Monolayer.

The cubic nonlinearity of a graphene-oxide monolayer was characterized through open and closed z-scan experiments, using a nano-second laser operating at a 10 Hz repetition rate and featuring a Gaussian spatial beam profile. The open z-scan revealed a reverse saturable absorption, indicating a positive nonlinear absorption coefficient, while the closed z-scan displayed valley-peak traces, indicative of positive nonlinear refraction. This observation suggests that, under the given excitation wavelength, a two-photon or two-step excitation process occurs due to the increased absorption in both the lower visible and upper UV wavelength regions. This finding implies that graphene oxide exhibits a higher excited-state absorption cross-section compared to its ground state. The resulting nonlinear absorption and nonlinear refraction coefficients were estimated to be approximately ~2.62 × 10-8 m/W and 3.9 × 10-15 m2/W, respectively. Additionally, this study sheds light on the interplay between nonlinear absorption and nonlinear refraction traces, providing valuable insights into the material's optical properties.

One-pot decoration of CdS and CdMoO4 nanoparticles on g-C3N4 nanoplates: Boosted photocatalytic degradation of tetracycline

Photocatalytic water detoxification has been a hot-spot research field in recent years. In this regard, CdS and CdMoO4 nanoparticles were decorated on g-C3N4 nanoplates via a one-pot hydrothermal route. The morphology, structure, phase, surface properties, electrochemical, and optical properties of the resultant materials were identified by XRD, FT-IR, UV–vis DRS, FESEM, TEM, HRTEM, XPS, EDX, EIS, BET, BJH, and PL analyses. The optimum ternary nanocomposite exhibited boosted activity for degradation of tetracycline (TC), Congo red (CR), methylene blue (MB), methyl orange (MO), and malachite green (MG) upon visible light, which was 41.6, 29.0, 16.1, 27.4, and 38.2 times higher than pristine g-C3N4. The UV–vis DRS, EIS, PL, and BET analyses attributed the boosted activity to the generation of more charge carriers, promoted segregation and transfer of charges, and extended surface area. The quenching experiments confirmed the crucial role of holes and superoxide anion radicals in the degradation reaction. Eventually, based on the outcomes, a probable mechanism for the boosted photocatalytic ability was discussed.

Exploring the physical properties of quaternary fluoro-elpasolites A2 NaInF6 (A = Cs,Rb)compounds for prospective technological applications

The double perovskite materials possess exceptional traits that make them highly suitable for energy-related applications, owing to their eco-friendliness, efficiency, and lack of toxicity. Using the density functional theory implemented in WIEN2K, we conducted a thorough examination of the electronic, structural, optical, and elastic characteristics of A2NaInF6 (A = Cs, Rb) double perovskite materials. The energy formation and the Birch-Murnaghan equation of state fitting curve guarantee both thermodynamic and structural stability. The optimized lattice parameters obtained from our computations are in agreement with the experimental values for the relevant compounds. For calculating the electronic and optical properties of both materials, the widely used TB-mBJ (Trans Blaha modified Becke–Johnson) approximation is utilized. The replacement of ‘Cs’ with ‘Rb’ results in the tuning of the band gap from 7.70 eV to 5.01 eV. After analyzing the mechanical properties, it is anticipated that both materials exhibit elastic stability, brittleness, and relatively lower hardness. The optical properties are computed, analyzed, and presented across a broad energy range of 0–30 eV of incident photon energy. The absorption coefficient, which is a part of the optical properties, highlights the potential of these materials as fundamental components for optoelectronic devices operating in the extreme ultraviolet (XUV) region. The outcomes of our study could provide valuable insights for the development of high-performance optoelectronic devices.