Optical Absorption Spectra Research Articles

Impact of bismuth oxide on structural, optical and gamma-ray shielding properties of calcium-sodium-borate glasses.

In the present study, we have prepared six glass samples of bismuth borate using the melt-quenching method with the composition (70-x)B2O3-10CaO-20Na2O-xBi2O3; x=0, 3, 6, 9, 12 and 15mol%. The density of the prepared glasses was determined using Archimedes principle. The X-ray diffraction patterns provide confirmation of the amorphous nature of the prepared samples, whereas the Fourier transform infrared measurements pointed to the existence of structural units like BO3, BO4, BiO3 and BiO6 within the glass network. An assessment of the optical absorption spectra unveiled that with the increase in the bismuth oxide content, there was a decrease observed in both the direct and indirect band gap energies. Specifically, they decreased from 3.40 to 2.79eV and from 3.10 to 2.46eV, respectively. The properties related to gamma ray attenuation, including the mass attenuation coefficient (μm), effective atomic number (Zeff), half-value layer (HVL) and mean free path (MFP), were examined for all the glass samples. This investigation was carried out using the Phy-X/PSD software, covering the energy range from 0.511 to 1.332MeV. Out of all the samples, Bi-15, featuring the highest Bi2O3 content, demonstrated the highest μm, Zeff, the smallest HVL and MFP. These results suggest that the glass with 15mol% of Bi2O3 offers the most effective gamma radiation shielding performance. Moreover, the glasses examined in this study exhibit superior radiation shielding characteristics compared with specific concrete types, namely, ordinary concrete, Hematite serpentine concrete and barite concrete, as well as commercial glasses such as RS-360 and RS-253.

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.

DFT analysis of elastic and optoelectronic properties of Cs2NaXCl6 (X=In, La, Sc, Y) double perovskite compounds

This study employs first-principles Density Functional Theory (DFT) to investigate the structural, electronic, and optical properties of double perovskites Cs2NaXCl6 (X = In, La, Sc, and Y) compounds. By applying various functionals (GGA-PBE, GGA-PBEsol, HSE06, and mBJ), we ensure an accurate and thorough description of their electronic structures and other physical properties. Our analysis reveals excellent mechanical, thermodynamic, and dynamical stability of Cs2NaXCl6 compounds. Band gap calculations employing mBJ and HSE06 functionals reveal wide direct band gaps ranging from 4.1 to 6.4 eV, with notable contributions from Cl-p states near the valence band maximum. Furthermore, electron density analysis highlights a mixed covalent-ionic bonding nature, predominantly ionic. Additionally, the optical conductivity and absorption spectra peaks extend beyond the visible region, indicating potential applications in ultraviolet (UV) technologies. Finally, thermal conductivity analyses exhibit a significant reduction with increasing temperature, suggesting promising applications in high-temperature thermal insulation.

Spectroscopic properties and luminescence of the lithium tetraborate glasses co-doped with manganese and europium

High quality Li2B4O7:Mn,Eu glasses containing 1.0 mol.% MnO2 and Eu2O3 were prepared and investigated by XRD, EPR and optical spectroscopy techniques. Obtained data analysis shows that Mn is incorporated into the glass network as Mn2+ and Mn3+. Parameters of observed Mn2+ EPR signals in the Li2B4O7:Mn,Eu glasses were determined. Optical absorption spectrum of the studied glasses consists of broad band at 464 nm corresponding to the 5Eg(D) → 5T2g(D) transition of Mn3+ (3d4) ions and few narrow weak bands of the Eu3+ (4f6) ions. Emission spectra of the Li2B4O7:Mn,Eu glasses in orange-red region exhibit several sharp bands corresponding to the 5D0 → 7FJ (J = 0–4) transitions of Eu3+ ions and broad band belonging to the 4T1g(G) → 6A1g(S) transition of Mn2+ (3d5) ions. Comparative discussions were made on the luminescence spectra and decay curves of Mn2+ and Eu3+ ions in the Li2B4O7:Mn,Eu glasses and those in Mn-doped and Eu-doped glasses with the Li2B4O7 basic composition.

Investigations of the physical behavior of Cr2PX (X = C and N) MAX phases through first-principles calculations

MAX phases display an exclusive combination of ceramic and metallic characteristics, which makes them highly promising for various technological applications. This study investigated MAX phases of 211-type based on Cr2PX (X = C and N) by focusing on their physical properties, mainly the magnetic, electronic, and optical behaviors. The results obtained using the “density functional theory (DFT) based full-potential linearized augmented plane wave (FP-LAPW) method” matched those reported in the literature, indicating the reliability of the adopted methodology. The stabilities of the Cr2PX were validated by calculating their cohesive energies and phonon band structures. These compounds demonstrate identical energies for nonmagnetic, ferromagnetic, and antiferromagnetic phases and exhibit symmetrical arrangements of the “density of states (DOS)” for both up and down spins. Moreover, these MAX phases exhibit high optical absorption (∼10−6cm−1) and anisotropic reflectivity spectra, emphasizing the role of crystallographic orientation and their potential for applications in photovoltaics and other optical devices. These findings will provide valuable insights into the properties and behaviors of Cr2PX-based 211-MAX phases, thereby establishing the foundation for further research and potential applications across diverse areas.

Green Sonochemical Synthesis of rGO Nanosheets‐Decorated by SnO2 Nanoparticles for Nitrogen Gas‐Sensing Applications

In recent years, the development of efficient and environmentally friendly synthesis methods for nanomaterials has gained significant attention in various research fields, particularly in gas‐sensing applications. Among these methods, ultrasonic synthesis stands out for its simplicity, cost‐effectiveness, and ecofriendly nature. Herein, a simple and green ultrasonic synthesis process is used to synthesize the SnO2 nanoparticles‐decorated rGO nanosheets. The obtained X‐ray diffraction reveals the tetragonal rutile‐type crystal structure. The transmission electron microscopy images reveal the decoration of SnO2 nanoparticles on the surfaces of the rGO sheets. SnO2 nanoparticles of size 4–8 nm are identified on the surfaces of the rGO sheets. Furthermore, the optical absorbance and photoluminescence spectra of the nanocomposites validate charge migrations occurring at the interface of SnO2 and the rGO sheets. Compared to the pristine SnO2 nanoparticles, the green ultrasonically synthesized SnO2 nanoparticles‐decorated SnO2/rGO nanocomposite exhibits better sensing performance against NO2 gas and shows selectivity for NO2 gas at 200 °C. The SnO2/rGO nanocomposite demonstrates high NO2 sensing with appealing sensing properties such as excellent responsiveness (67% at 400 °C), rapid reaction time (18 s), and short recovery time (25 s).

Structural investigation of lithium bismuth borate glasses through Raman and infrared spectroscopies

AbstractThe structure of lithium bismuth borate glasses in the compositional series xBi2O3–25Li2O–(75 − x) B2O3 was studied with the use of Raman and infrared (IR) spectroscopies. Transparent glasses formed between x = 0 and 55, whereas glass–ceramics formed between x = 60 and 75 mol% Bi2O3. Structural investigation on the borate network showed that the glasses were undermodified at high Bi2O3 compositions with metaborate, pyroborate, and orthoborate triangles and tetrahedra being present past the stoichiometric orthoborate compositions (O/B = 3). Bi2O3 was found to participate in the glass as both a network former and modifier, as observed in the Raman and IR spectra. Optical absorption spectra of the glasses show a redshift of the absorption edge with increased Bi2O3. Optical, thermal, and physical properties of the glasses were examined and correlated to the structural evolution.

Deriving the star formation histories of galaxies from spectra with simulation-based inference

High-resolution galaxy spectra encode information about the stellar populations within galaxies. The properties of the stars, such as their ages, masses, and metallicities, provide insights into the underlying physical processes that drive the growth and transformation of galaxies over cosmic time. We explore a simulation-based inference (SBI) workflow to infer from optical absorption spectra the posterior distributions of metallicities and the star formation histories (SFHs) of galaxies (i.e. the star formation rate as a function of time). We generated a dataset of synthetic spectra to train and test our model using the spectroscopic predictions of the MILES stellar population library and non-parametric SFHs. We reliably estimate the mass assembly of an integrated stellar population with well-calibrated uncertainties. Specifically, we reach a score of $0.97\,R^2$ for the time at which a given galaxy from the test set formed $50<!PCT!>$ of its stellar mass, obtaining samples of the posteriors in only $\,s. We then applied the pipeline to real observations of massive elliptical galaxies, recovering the well-known relationship between the age and the velocity dispersion, and show that the most massive galaxies ($ km/s) built up to 90<!PCT!> of their total stellar masses within $1$\,Gyr of the Big Bang. The inferred properties also agree with the state-of-the-art inversion codes, but the inference is performed up to five orders of magnitude faster. This SBI approach coupled with machine learning and applied to full spectral fitting makes it possible to address large numbers of galaxies while performing a thick sampling of the posteriors. It will allow both the deterministic trends and the inherent uncertainties of the highly degenerated inversion problem to be estimated for large and complex upcoming spectroscopic surveys, such as DESI, WEAVE, or 4MOST.

تحسين الخصائص البصرية لأوكسيد القصدير النانوي في بوليمر بولي فينيل الكحول الغروي المحضر بطريقة الاستئصال بالليزر

المركبات النانوية هي مواد مناسبة لتلبية الطلبات الناشئة الناتجة عن التقدم في العلوم والتكنولوجيا. المكونات ذات الهياكل الجديدة و الكفاءة الافضل مقارنة بالمكونات المعالجة تقليديًا مطلوبة للتقدم التكنولوجي. في هذا البحث , يمكن إنشاء مركبات نانوية غروية غير عضوية من البوليمر باستخدام الاستئصال بالليزر النبضي لجسيمات أكسيد القصدير النانوية في بوليمر البولي فينيل الكحول كمضيف. تم استخدام الخصائص البصرية وأطياف الامتصاص للنظر في الخصائص البصرية للمركب النانوي. تم قياس فجوة الطاقة (Eg) ، وتم تحديد الانتقال غير المباشر لقيم بوليمر بولي فينيل الكحول النقي لتكون 5 الكترون . فولت و 3.5 الكترون . فولت للمركب النانوي PVA-SnO2. تم قياس العينات لمعامل الانقراض (k) ، معامل الانكسار (n)، وثابت العزل الكهربائي. انخفض ثابت العزل الكهربائي للمركبات النانوية مع زيادة معامل الامتصاص ، معامل الانكسار ، ومعامل الخمود. تتمتع المركبات النانوية بقدرة امتصاص عالية في منطقة الأشعة فوق البنفسجية ويمكن استخدامها لتغطية المواد لتطبيقات الحماية من الإشعاع.

Structural, morphological, optical and electrical characterization of MgO thin films grown by sputtering technique on different substrates

Magnesium Oxide (MgO) thin film structures were deposited on glass and n-Si substrates by means of RF magnetron sputtering technique. Structural, morphological, optical characteristics of MgO thin film were determined by XRD, AFM and UV–Vis spectrometer techniques. The optical properties like absorption coefficient and optical band gap were extracted using optical transmittance and absorption spectra. The band-gap of MgO thin film was determined for direct electronic transition. Additionally, electric parameters like ideality factor, saturation current and barrier height of the Au/MgO/n-Si device were computed from the forward I–V data in dark state. The ideality factor was found to be greater than one. This indicates that the I–V characteristics of the device exhibits non-ideal attitude. The results show that the MgO thin film can be applied to both optical and electronic device applications.

Effect of Ca co-doping on gamma-stimulated luminescence of Lu2SiO5:Ce

In order to estimate the stability of the light output of the scintillation detector, the Lu2SiO5:Ce scintillation crystals, additionally doped with Ca2+ ions at concentrations of 0 ÷ 0.4 at%, were studied. The spectra of optical absorption, gamma-luminescence, thermal luminescence, dose and temperature dependences of luminescence were measured. Gamma-luminescence in the dose range 10 - 5·107 Gy was recorded using 60Co gamma-source at the temperature range of 310–460 K. In contrast to the initial sample (non-doped with Ca), in the sample doped with 0.1 at% of Ca, an increase in the luminescence intensity was observed in the range of 390–425 nm, but further with an increase in the concentration of Ca (0.3–0.4 at%), the intensity of this band decreased to the initial level (undoped). At Ca concentrations of 0.3 and 0.4 at%, the intensity of the Ce1 center band remains practically unchanged up to a dose of 5·107 Gy. LSO crystals doped with Ce 0.1 at% and co-doped with Ca 0.1 at% can be recommended as a scintillation detector up to a gamma-dose of 105 Gy at room temperature.

Unique electronic and optical properties of ABBA tetralayer graphene under external electric fields

In this study, we examine the electronic and optical properties of ABBA-stacked tetralayer graphene (4LG), emphasizing its unique characteristics in contrast to its counterparts. The full tight-binding model elucidates the significance of interlayer couplings in the system. We investigate the influence of gate voltage on the system and uncover alterations in the band structure, the emergence of edge states, and the formation of band gaps. The analysis of the density of states reveals the existence of van Hove singularities, which dynamically evolve with the changing gate voltage, resulting in a transition from semimetallic to semiconductor properties. The optical absorption spectrum demonstrates asymmetrical peaks and step-like structures, further affected by a potential difference. Under a finite electric field, optical excitations in gated 4LG reveal triangular isoenergy loops with significant interaction-induced distortions of up to 100 meV. This study anticipates the potential for tuning optical properties in ABBA-stacked 4LG through external electric fields, offering opportunities for experimental exploration.

Structural, optoelectronic, and magnetic behaviors of Li2BeTM (TM = V, Cr, Mn, Fe) Se4 compounds using DFT investigations

In this work, we present computational investigations of the electronic, the optical and the magnetic properties of the Li2BeTMSe4(TM = V, Cr, Mn, Fe) compounds using the first-principle calculations based on the density functional theory. In this respect, we employ the generalized gradient approximation corrected by the Tran-Balaha modified Becke-Johnson exchange potential to obtain more accurate results. Among these outcomes, we first study the electronic properties such as the band energy dispersion and the state densities. Regarding this, the Li2BeTMSe4 quaternary family is found to have an indirect band gap of 1.910 eV, 1.905 eV, 2.223 eV and 1.278 eV for TM = V, Cr, Mn, and Fe, respectively. Further, an examination of the optical properties reveals that the computed optical absorption spectra cover a broad energy range in the visible and the ultraviolet spectrums. Motivated by spintronic applications, we additionally determine the total and the local magnetic moments. Then, we compute the associated Curie temperatures via a linear relation with the total magnetic moments. Among others, the Li2BeTMSe4(TM = V, Cr, Mn, Fe) materials involve acceptable temperatures showing potential applications for high temperature nano-devices activities. Comparing the obtained findings with the available ones, the acquired results indicate that the Li2BeTMSe4(TM = V, Cr, Mn, Fe) materials exhibit a wide range of applications in solar cells, optoelectronics, and other fields.

Antimicrobial efficiency against fish pathogens on the green synthesized silver nanoparticles

Fish-borne pathogens such as A. hydrophila and F. aquidurense are the most resistant strains in pisciculture farming. Removing the aforementioned pathogens without antibiotics presents a formidable challenge. To overcome this problem, silver nanoparticles (AgNPs) are synthesized using silver nitrate, water medium, and as an AzadirachtaIndica leaf extract via the green synthesis route. X-ray diffraction (XRD) pattern results authenticate the synthesized material is the face-centered cubic structure of silver. The optical absorption edge of the synthesized product was found at the wavelength of 440 nm from the UV–visible spectra, which is confirmed to relate to the Surface Plasmon Resonance peaks of silver particles. In addition, the optical band gap value of the synthesized Ag sample is measured to be 2.81 eV from the obtained optical absorption spectra. EDX spectrum of the synthesized product also supports confirming the silver particle formation. The FT-IR spectra of the neem extract and silver nanoparticles showed their characteristic functional groups, respectively. The presence of bands between 1000 cm−1 to 500 cm−1 indicates to the formation of silver particles. Spherical particles appeared in the synthesized Ag using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The particle size of Ag NPs was measured as 40 nm and 62 ± 10 nm by TEM and Dynamic Light Scattering (DLS). The zeta potential was also measured as −12 mV showing the synthesized sample's stable nature. Using the DPPH assay, synthesized AgNPs were taken along with the various concentrations of ascorbic acid (20, 40, 60, 80, and 100 μg/mL) to examine the free radical scavenging activity (RSA). RSA value is higher (84 ± 2 %) for synthesized AgNPs at higher concentration (100 μg/mL) than 21 ± 2 % at low concentration (100 μg/mL). The antimicrobial efficacy of the AgNPs against A. hydrophila and F. aquidurense was performed through the agar diffusion method and its results showed the inhibitory zones of the F.aquidurense and A. hydrophila were measured as 25 ± 3 mm, and 28 ± 4 mm respectively. The synthesized Ag particles showed excellent antimicrobial and antioxidant properties confirmed by antimicrobial and DPPH experiments. It implies that the green synthesized silver nanoparticles could be a good alternative for antibiotics in aquaculture farms. The exposure of low concentrations of silver nanoparticles to zebrafish and brine shrimp does not affect the viability and morphology. The exposure of silver nanoparticles in the fisheries in optimized concentration and time could control the fish-borne pathogens without antibiotics.

Optical absorption spectra in the far-infrared range and phonons of CdSe1−xTex thin films

Optical reflection spectra of CdSe1-xTex thin films deposited on quartz substrates are measured using the synchrotron radiation in the spectral range of 20–500 cm−1. The absorption bands of CdSe, CdTe, CdSe0.75Te0.25, CdSe0.5Te0.5, and CdSe0.25Te0.75 films are localized in the range of 20–220 cm−1. The imaginary parts of the dielectric function ε2(λ−1) of CdTe1-xSex crystals calculated in the framework of the density functional theory are in good agreement with the experimental reflection spectra of CdTe1-xSex films. The eigenvectors of the dynamical matrix CdTe1-xSex crystals are analyzed for several phonon modes to understand the difference between the frequency dependences of the calculated vibration density of states and the imaginary part of dielectric function ε2(λ−1). Small features of the experimental reflective spectra of CdSe1-xTex films in the ranges 50–70 cm−1 and 80–120 cm−1 are explained using the analysis of results of the molecular dynamics. During comparative molecular dynamics calculations, it was found that the vibration density of states of a thin CdTe slab with a surface-to-volume number of atoms relation of NS/NV = 0.2, experienced a redshift of approximately 30 cm−1. This shift was observed in comparison with the CdTe single crystal.

Evaluating Pb-based and Pb-free Halide Perovskites for Solar-Cell Applications: A Simulation Study

Metal halide Pb-based and Pb-free perovskite crystal structures are an essential class of optoelectronic materials due to their significant optoelectronic properties, optical absorption and tuneable emission spectrum properties. However, the most efficient optoelectronic devices were based on the Pb as a monovalent cation, but its toxicity is a significant hurdle for commercial device applications. Thus, replacing the toxic Pb with Pb-free alternatives (such as tin (Sn)) for diverse photovoltaic and optoelectronic applications is essential. Moreover, replacing the volatile methylammonium (MA) with cesium (Cs) leads to the development of an efficient perovskite absorber layer with improved optical & thermal stability and stabilized photoconversion efficiency. This paper discusses the correlation between the experimental and theoretical work for the Pb-based and Pb-free perovskites synthesised using the hot-injection method at different temperatures. Here, simulation is also carried out using the help of SCAPS-1D software to study the effect of various parameters of CsSnI3 and CsPbI3 layers on solar cell performance. This experimental and theoretical comparative study of the Hot-injection method synthesised CsPbI3 and CsSnI3 perovskites is rarely investigated for optoelectronic applications.

Synergistic enhancement of optical properties in erbium-doped borate glasses through copper nanoparticle incorporation

The present study investigated the impact of incorporating copper nanoparticles (CuNPs) on the optical properties of erbium-doped borate glasses. Through melt-quenching and heat treatment techniques, glasses with varying Cu2O concentrations (x = 0–5 mol%) were synthesized. Physical and structural analyses revealed that Cu ions serve as effective network modifiers. They foster the formation of a greater proportion of BO4 tetrahedra and thus enhancing glass homogeneity. Optical absorption spectra demonstrate a distinct modulation of Er3+ absorption bands with Cu2O embedding, indicating the formation of CuNPs, as validated by the emergence of surface plasmon resonance bands. This structural evolution results in a noticeable reduction in the bandgap energy, signifying improved semiconducting behavior. Judd-Ofelt analysis highlighted the profound influence of CuNPs on hypersensitive transitions, thereby affecting oscillator strength. Photoluminescence measurements revealed amplified emission in the visible red and near infrared (NIR) region, attributed to the synergistic effects of CuNPs and Er3+ ions, with 5 mol % Cu2O exhibiting the highest emission intensity. Analysis of the radiative properties validates the enhancement of the emission cross-section, gain bandwidth, optical gain and radiative transitions. These enhancements contribute to a notable increase in the branching ratio from 0.91 % to 5.41 % accompanied by an increase in the quantum efficiency from ∼79 % to ∼90 %. Moreover, decay analysis revealed a notable enhancement in lifetime from 3.03 ms to 15.74 ms, which is indicative of enhanced radiative transitions. Overall, the incorporation of CuNPs into erbium-doped borate glasses facilitates significant enhancements in physical, structural, and optical properties. This positions them as promising materials for a wide array of optoelectronic applications. This comprehensive study sheds light on the complex interplay between CuNPs and erbium-barium borate glasses, offering valuable insights for the development of advanced optoelectronic materials with enhanced performance and functionality.

Structure and gamma attenuation behavior of copper ions in host glass from the system (P2O5–LiF–CaF2)

Copper-doped lithium calcium fluorophosphate glasses in the compositional system (60−x)P2O5·20LiF·20CaF2·xCuO (x = 0−3 mol%) were prepared using the conventional melt quenching technique. X-ray diffraction confirmed the amorphous, non-crystalline phase of the glasses. Optical absorption spectra indicated the presence of additional broad visible-NIR absorption bands upon CuO doping, attributed to distorted Cu2+ ions. Possible overlaps from Jahn-Teller distorted sites or clustering into nanodomains may contribute to band broadening. The direct optical bandgap was found to reduce from 3.89 eV to 1.17 eV with increasing CuO content. The study of physical parameters showed almost linear variation in density (2.62–2.95 g/cm3) and molar volume (40.45–35.29 cm3/mol) with incremental CuO substitution, explained by changes in structural packing efficiency and formation of Cu–O complexes. FTIR spectra revealed vibrations corresponding to phosphate structural groups. The simulation of radiation shielding parameters displayed steady improvements with higher CuO fractions, which were related to enhanced photon interactions via photoelectric absorption and Compton scattering.

Tuning the potentials of aluminum phosphide nanotube photocatalyst for wastewater treatment through band gap engineering: a DFT study

The photocatalytic properties of semiconductor materials, which are controllable through the design of the bandgap structure, make them a promising catalyst for wastewater treatment. This work investigated the photocatalytic properties of single-walled aluminum phosphide nanotube (SWAlPNT) doped with different concentrations of boron (B) atoms for wastewater treatment. Analysis of the structural, electronic and optical properties of the SWAlPNT photocatalyst was performed using the density functional theory approach in terms of plane wave basis set and pseudopotential. SWAlPNT was found to be stable to B doping with 3.6% and 7.1% concentrations. The obtained formation energy values of 12.33 eV, 12.00 eV and 11.98 eV and also cohesive energies of −0.82, eV, −0.75 eV and 0.79 eV for pristine, 3.6% and 7.1% B-doped SWAlPNTs, revealed the systems’ well mechanical and thermodynamic stabilities. Results also revealed that cohesive energy decreases with an increase in concentration of B dopant, which significantly enhances efficient thermal stability. Electronic band gap calculations revealed that pristine SWAlPNT demonstrated a direct band gap value of 0.2 eV. Due to B doping, an indirect band gap value of 1.4 eV was obtained with 3.6% B-doped SWAlPNT, which agreed well with band gaps of other photocatalysts used for wastewater purification. Analysis using optical absorption spectra revealed that 3.6% B-doped system absorbs visible light while 7.1% doped system absorbs both visible and ultraviolet light. This study found both 3.6% and 7.1% B-doped SWAlPNT as suitable photocatalysts for wastewater treatment under solar irradiation, with the 3.6% B-doped system demonstrating relatively better performance for wastewater treatment.

Employing molecular dynamics simulations and DFT calculations to elucidate the energetic, structural, and spectroscopic attributes of (poly)valines in water solution

In this study, we explored how the growth of peptide chains containing valines impacts nuclear magnetic resonance (NMR) and optical absorption spectra. Results stem from equilibrated configurations in water, reflecting solvent influence and valine vibration. Utilizing fully atomistic molecular dynamics (MD), simulations, and density functional theory (DFT) including TD-DFT, we observe a notable shift in optical absorption towards longer wavelengths with increased valine count. Additionally, carbon atom magnetic signatures unveil distinct peptide bond characteristics. This work sheds light on the spectroscopic behavior of valine-rich peptide chains, crucial for understanding structural and functional properties, particularly in biomolecular contexts.