Linear Absorption Research Articles

DFT and Model Hamiltonian Study of Optoelectronic Properties of Some Low-Symmetry Graphene Quantum Dots.

We have studied the electronic and optical properties of three low-symmetry graphene quantum dots (GQDs), with point-group symmetries C2v and C2h. For the calculations of linear optical absorption spectra, we employed both first-principles time-dependent density-functional theory (TDDFT) and the electron-correlated Pariser-Parr-Pople (PPP) model coupled with the configuration-interaction (CI) approach. In the PPP-CI approach, calculations were performed using both screened and standard parameters, along with efficiently incorporating electron correlation effects using multireference singles-doubles CI for both ground and excited states. We assume that the GQDs are saturated by hydrogen atoms at the edges, making them effectively polycyclic aromatic hydrocarbons (PAHs) dibenzo[bc,ef]coronene (also known as benzo(1,14)bisanthene, C30H14) and two isomeric compounds, dinaphtho[8,1,2abc;2',1',8'klm]coronene and dinaphtho[8,1,2abc;2',1',8'jkl]coronene with the chemical formula C36H16. The two isomers have different point group symmetries; therefore, this study will also help us understand the influence of symmetry on the optical properties. A common feature of the absorption spectra of the three GQDs is that the first peak representing the optical gap is of low to moderate intensity, while the intense peaks appear at higher energies. For each GQD, PPP model calculations performed with the screened parameters agree well with the experimental results of the corresponding PAH and also with the TDDFT calculations. To further quantify the influence of electron-correlation effects, we also computed the singlet-triplet gap (spin gap) of the three GQDs, and we found them to be significant.

Kinetics of nirogacestat-mediated increases in B-cell maturation antigen on plasma cells inform therapeutic combinations in multiple myeloma.

B-cell maturation antigen (BCMA) is the target of several investigational and approved drugs for multiple myeloma (MM). BCMA expressed on plasma cells (PCs) and MM cells is cleaved by the enzyme gamma secretase, reducing membrane-bound BCMA (mbBCMA) receptor density. Gamma secretase inhibitors (GSIs) have been shown to increase mbBCMA density and may enhance efficacy of BCMA-targeted therapies. The pharmacodynamic profile of the GSI nirogacestat was evaluated in MM cell lines and a phase 1 study in healthy volunteers. In MM cell lines, mbBCMA density and soluble BCMA (sBCMA) concentrations were measured before and after short-duration nirogacestat exposure and at serial timepoints following washout. In the phase 1 study, 23 participants were administered a single oral dose of nirogacestat 50, 150, or 300 mg or repeated doses of 100 mg every 12h for up to 48h; mbBCMA density on PCs (from whole blood and bone marrow) and nirogacestat plasma concentrations were measured at baseline and postdose. After single-dose administration, serum nirogacestat concentrations rapidly increased (Tmax ~1h), and a two-compartment model with linear absorption and clearance best described nirogacestat pharmacokinetics. In MM cells and healthy volunteers' PCs, nirogacestat resulted in rapid and robust increases in mbBCMA density, with increases up to 20-fold within 4-8h of exposure. Concomitant decreases in sBCMA were observed. Nirogacestat is currently being evaluated in combination with several BCMA-directed therapeutic agents in patients with MM. Elucidating the kinetics of BCMA in response to nirogacestat is key to guiding dosing and therapeutic strategies in MM.

Peierls Distortion Induced Giant Linear Dichroism, Second-Harmonic Generation, and In-Plane Ferroelectricity in NbOBr2.

The Peierls distortion plays an essential role in governing the in-plane ferroelectricity and nonlinear optical characteristics of anisotropic niobium oxide dihalides, such as NbOCl2 and NbOI2. Despite its significance, experimental investigation into the structural, optical, and ferroelectric properties of NbOBr2 has been lacking. Here, the successful fabrication of centimeter-sized, high-quality NbOBr2 single crystals, enabling direct observation of Peierls distortion using aberration-corrected scanning transmission electron microscopy, is reported. Notably, the magnitude of Peierls distortion in NbOBr2 falls between that observed in NbOCl2 and NbOI2. Furthermore, the existence of giant linear dichroism absorption and second-harmonic generation (SHG) phenomena associated with Peierls distortion is confirmed. Exfoliated NbOBr2 flakes exhibit single-domain ferroelectricity, with the polarization switchable by an electric field. Temperature-dependent SHG measurements reveal a Curie temperature of ≈502K for ferroelectric NbOBr2. This work demonstrates that NbOBr2 holds promise for polarized nonlinear optical devices, as well as for nonvolatile information processing and storage devices.

State analysis of a biobased hydrogel subjected to freeze and thaw processes by X ray absorption spectroscopy using synchrotron radiation

Freezing hydrogels can compromise their network structures and modify their properties as a result of ice crystal formation. Therefore, understanding the internal structure, including ice crystals and the state of chemical components within hydrogels, is essential. In this study, we evaluated the elemental distribution in bio-based hydrogels subjected to freezing-thaw process using X-ray absorption spectroscopy with synchrotron radiation. A bio-based hydrogel, prepared from Alaska pollock, underwent both slow and rapid freezing processes. Tomographic images and linear X-ray absorption coefficient distributions of the rapidly frozen hydrogel displayed a uniform image with a mean absorption coefficient of 2.81 cm−1. Conversely, the slowly frozen sample exhibited distinct contrasts with peaks at 2.516 cm−1 (dark) and 3.691 cm−1 (bright), occupying 28% and 72% of the image, respectively. The mean absorption coefficient of the slowly frozen sample was comparable to that of the rapidly frozen sample, indicating no elemental loss. The elements within the hydrogel were categorized into organic elements, macrominerals, and trace elements. The bright areas in the images were attributed to the concentration of macrominerals. Notably, Cl and Na were the primary contributors to the absorption coefficients among the elements present, signifying salt migration during freezing. These findings suggest that the contrast observed in X-ray computed tomography images after freezing reflects the elemental distribution within the hydrogel and successfully demonstrates element localization due to cryoconcentration.

Theoretical Investigation of Nonlinear Optical Properties and Molecular Docking of Carbazoles Derived from Murraya Koenigii

AbstractIn this study, the density functional theory (DFT) method is used to theoretically investigate the nonlinear optical (NLO) properties of natural carbazoles. The selected carbazoles have significant NLO characteristics. Using the B3LYP/6‐311++G(d,p) and CAM‐B3LYP/6‐311++G(d,p) level theories, the linear optical absorption, HOMO‐LUMO energy gap, molecular electrostatic potential (MEP), and dipole moments were calculated. The first hyperpolarizability (β0), second hyperpolarizability (γ), and static and dynamic linear polarizability (α0) components were computed. Electron correlation was obtained, which was compared with NLO and docking studies showing good relation with both. All carbazole compounds demonstrate good optoelectronic qualities that promote their potential use in electronic devices, as demonstrated by the frequency‐dependent dynamic hyperpolarizabilities of the B3LYP/6‐311++G(d,p) and CAM‐B3LYP/6‐311++G(d,p) functionals at 532 and 1064 nm wavelengths. The results of the molecular docking study shows that CBZ molecules exhibit a strong affinity for both Malassezia globosa (SMG1) lipase targets. The docking data demonstrated a strong binding ability, with CBZ7 and CBZ3. This indicates that CBZ7 and CBZ3 outperform all other compounds and have a high binding capability to the target protein.

Structure Determination of Zinc and Cadmium Dication Complexes with Intact and Deprotonated Histidyl Glycine and Glycyl Histidine Dipeptides.

Metalated intact and deprotonated histidyl glycine and glycyl histidine dipeptides were investigated in the gas phase by using infrared multiple photon dissociation (IRMPD) spectroscopy with light from a free-electron laser (FEL). The dipeptides M2+(GlyHis), M2+(HisGly), [M(GlyHis-H)]+, and [M(HisGly-H)]+, where M = Zn and Cd, were probed to elucidate how the His position along the peptide chain and ligand charge state might influence the structures observed in the gas phase. Simulated annealing calculations were performed to determine energetically low-lying conformers and isomers of these structures. Quantum chemical calculations were used to optimize the structures at the B3LYP level of theory using the 6-311+G(d,p) and def2-TZVP basis sets for zinc and cadmium complexes, respectively. IRMPD and calculated linear absorption spectra were compared to evaluate which structures are present. Relative energies of the various species were evaluated using single-point energy calculations for low-lying structures at the B3LYP, B3LYP-GD3BJ, ωB97XD, and MP2(full) levels using the 6-311+G(2d,2p) and def2-TZVPP basis sets. For all species, structures for both metals mirror each other, and those that reproduce the experimental spectrum were determined to be iminol structures for the intact ligands or iminol-like structures for the deprotonated ligands. Additionally, when the spectra of the deprotonated dipeptides are compared to the intact dipeptides, the change in the spectra is correlated to the group that is deprotonated.

Toward tailored light absorption manipulation by Kerr nonlinear nanoslits within a grating Fabry-Perot cavity coupled with reconfigurable GST225 material

In this paper, we investigate the absorption tunability of a silver plasmonic grating incorporating Kerr-type nonlinear graphene-oxide (GO) nanoslits and Ge2Sb2Te5 (GST225) phase-change material at telecom wavelengths. The linear absorption spectra reveal that the amorphous GST225 grating exhibits two distinct absorption peaks, while half-crystallization leads to a single pronounced peak, and full crystallization results in a redshifted peak with a slightly decreased value. These findings confirm that the crystalline degree of GST225 significantly modulates the absorption characteristics. Upon exposure to a nanosecond Gaussian pulse laser irradiation with appropriate fluences, the electric field confinement within the nanoslits intensifies, particularly at the center of the pulse, leading to a pronounced absorption adjustment due to Kerr nonlinearity. Temporal examination at the L-band wavelength of 1591.5 nm reveals a U-shaped absorption response for both amorphous and crystalline GST225, with a pronounced dip at the pulse’s peak. In the half-crystallized state, the weak linear absorption can be substantially enhanced at both the leading and trailing edges of the pulse, with a dip at the center, illustrating the Kerr nonlinearity within the GO nanoslits. The dynamic behavior of absorption under different laser fluences underscores the potential of this system for high-contrast optical switching. Our results offer insights into the development of reconfigurable optical switches utilizing nonlinear Kerr effects, paving the way for advancements in tunable optical communication technologies.

Spectrum Broadening Due to Nonselective Linear Absorption

The position and linewidth of an emission spectrum reflect the physical properties of the luminophor. So, keeping the spectrum from distortion is very important in its measurement. However, we find that the spectrum linewidth will be broadened when the near-infrared radiation from a sodium lamp passes through a nonselective linear absorbing filter. This counterintuitive linewidth-broadening phenomenon is obvious when the residual light power after the filter is low enough, typically lower than 2.48×10−4 μW. This novel linewidth-broadening effect is different from the well-known Lorentzian, Doppler, and Voigt broadening, and is likely to be more independent evidence of the discrete wavelet structure of classical plane light waves. The effect is significant in high-sensitivity spectroscopy measurements, for example streak camera spectroscopy and Raman spectroscopy experiments. In addition, this effect may also be significant for cosmological research.

Dual-channel bistability modulation in a bilayer graphene-based optomechanical system.

We propose a flexible scheme for studying linear absorption response and optical bistability (OB) in a bilayer graphene-based optomechanical system. The results show that as the coupling between the G-mode phonon and excitons is turned on, the linear absorption spectrum will evolve from a single-peaked structure to a two-peaked one, and the spacing between two splitting peaks is equal to twice as large as the phonon-exciton coupling strength. Especially, we plot bistability phase diagrams within the system's parameter subspaces, demonstrating that the bistable switch can be controlled via no, single, or dual-channel by changing the intensity of the pump light in a weak phonon-exciton coupling regime. This holds promise for developing precision-measuring nanodevices and multi-channel optical bistable switches.

Anisotropic nonlinear optical responses of Ta2NiS5 flake towards ultrafast logic gates and secure all-optical information transmission

Abstract Optical logic gates based on nonlinear optical property of material with ultrafast response speed and excellent computational processing power can break the performance bottleneck of electronic transistors. As one of the layered 2D materials, Ta2NiS5 exhibits high anisotropic mobility, exotic electrical response, and intriguing optical properties. Due to the low-symmetrical crystal structures, it possesses in-plane anisotropic physical properties. The optical absorption information of Ta2NiS5 is investigated by anisotropic linear absorption spectra, femtosecond laser intensity scanning (I-scan), and non-degenerate pump-probe technology. The I-scan results show a distinct maximum of ∼4.9 % saturable absorption (SA) and ∼4 % reverse saturable absorption (RSA) at different polarization directions of the incident laser. And, these unique nonlinear optical (NLO) properties originate from the anisotropic optical transition probability. Furthermore, the novel Ta2NiS5-based all-optical logic gates are proposed by manipulating the NLO absorption processes. And, the all-optical OR and NOR logic gates possess an ultrafast response speed approaching 1.7 THz. Meanwhile, an all-optical information transmission method with higher security and accuracy is achieved, which has promising potential to avoid the disclosure of information. This work provides a new path for designing versatile and novel optical applications based on Ta2NiS5 materials.

Evaluation of Clayey Raw Materials and Ceramic Masses from Ceramic Building Material Companies Located in Northeastern Brazil

The challenge of improving the quality of ceramic products is faced worldwide, especially in areas where artisanal production is common and the need for in-depth knowledge about raw materials, together with inefficient production processes, limits the advancement of the ceramic industry. Scientifically, detailed investigation of ceramic masses’ physical, chemical and mechanical properties can provide essential insights to optimize production, contribute to developing more advanced and sustainable techniques, and increase competitiveness. This study evaluated raw clay materials and ceramic masses obtained from northeastern Brazilian, focusing on their chemical composition, mineralogical phases, thermal behavior, and particle size distribution. Rectangular samples (80 mm × 20 mm × 7 mm) prepared using uniaxial pressing (25 MPa by 30 s) were fired at different temperatures (950 and 1050 °C) and linear shrinkage, flexural strength, water absorption, and apparent porosity measurements were taken. The results showed that the companies still need to improve the production process to meet the minimum strength requirement of 1.5 MPa according to the Brazilian standard NBR 15270.

Natural radioactivity and technological properties of kaolinized granite from the Motajica mine, Bosnia and Herzegovina

For the production of ceramic tiles, it is necessary to use high-quality and economical raw materials, which will optimize the properties of the final product and meet the prescribed standards. For this reason, it is necessary to examine the properties of each potential raw material. This paper examines radioactivity and technological properties of kaolinized granite from the Motajica mine, in Bosnia and Herzegovina. Chemical analysis, X-ray diffraction (XRD), and thermal analysis (DTA) were carried out. In order to examine the technological (ceramic) properties of this raw material, ignition tests of the composite obtained by introducing kaolinized granite (with a content of 25 %) into the standard factory series of ceramic tiles were conducted at four selected temperatures (1050, 1100, 1120, and 1150 ℃). Total linear shrinkage, flexural strength, and water absorption were determined for the produced biscuit. Using gamma spectrometry, the activity concentrations of radionuclides 226Ra, 232Th and, 40K were measured, and then the radiation risk for external exposure of workers in the industry was assessed using hazard indices and doses. The radiation risk from the use of manufactured unglazed ceramic tiles in houses was also assessed. Statistical analysis of radionuclides for 100 samples of kaolinized granite was performed using descriptive statistics and hierarchical cluster analysis (HCA). It was observed that the average values of 226Ra, 232Th, and 40K are above the average for building materials in the world and amount respectively to 122 Bq kg−1, 96 Bq kg−1, and 1068 Bq kg−1. All other obtained values indicate that it is a quality raw material that, despite having an increased content of radioactive elements compared to the world average, does not represent a radiological hazard for workers and people who stay indoors on an annual basis. The tested raw material satisfies all technological criteria for further use and can be considered a desirable ingredient of ceramic composites because it can partially or completely replace feldspar.

Effects of multiple reflections on nonlinear absorption measurements.

Accurate measurement of nonlinear absorption coefficients by transmission-based techniques, such as Z-scan and its modifications, remains challenging due to high measurement errors. In this Letter, we claim that one of the reasons for that could lie in ignoring multiple reflections of light in plane-parallel samples in the presence of multi-photon excitation. Closed-form formulations for transmittance and reflectance coefficients, considering both linear and multiphoton absorption, are obtained in the geometrical optics approximation. The contributions of multiple reflections to the total transmittance are calculated for several II-VI materials reported in the literature. The results show a nonlinear dependence on incident intensity, ranging from 15.7% down to 7.9% for CdS, from 10.3% down to 5.8% for CdSe, and from 18.1% down to 9.1% for ZnSe. The dependence of the contribution of multiple reflections on the sample thickness is shown to exhibit a near exponential decay.

Dynamic tunability of NIR absorption in a plasmonic grating through nonlinear kerr-effect of graphene-oxide and photothermal phase transition of GSST

In this paper, we present an in-depth examination of the absorption dynamics of a silver plasmonic grating incorporating Kerr-type nonlinear graphene-oxide (GO) nanoslits and a Ge2Sb2Se4Te1 (GSST) phase-change material, both in linear and nonlinear regimes. Linear absorption approaches unity at the resonant wavelength when GSST is amorphous. Upon exposure to a nanosecond Gaussian pulse laser irradiation with appropriate fluences, the amorphous GSST partially crystallizes through a thermoplasmonic-induced process, resulting in a significant reduction of the linear on-resonance absorption in the form of a step-like curve. Additionally, the weak off-resonance linear absorption of the system can be enhanced owing to the non-uniform phase-transition within the GSST. Transitioning to a nonlinear regime, considering the third-order nonlinearity of GO nanoslits, reveals distinct absorption behaviors. Temporal analysis reveals that at the on-resonance wavelength, the unit absorption decreases with increasing laser intensity, reaching a minimum at the pulse peak due to the Kerr nonlinearity in the GO. Intriguingly, the absorption exhibits a U-shaped curve at lower fluences, while at higher fluences, it stabilizes at a lower value post-pulse peak where the amorphous GSST undergoes a thermally driven partially crystallization phase transformation. In the off-resonance mode, the weak absorption enhances dramatically by increasing the fluence, tracing an imperfect parabolic trajectory that reaches nearly unit at the trailing edge of the pulse, attributed to the Kerr nonlinearity within the GO nanoslits. By further increasing the laser fluence, the photothermal response of the GSST emerges as the dominant factor, diminishing the unity absorption observed at the trailing edge of the pulse. These findings underscore the dynamic responsiveness of the proposed grating to pulsed laser illumination, driven by the nonlinear Kerr effect and GSST reconfigurability, offering promising opportunities for developing active optical switching devices.

Magnetic field-engineered optical nonlinearity in germanene nanotubes

Abstract The linear and nonlinear optical properties of germanene nanotubes (GeNTs) under the influence of magnetic fields are investigated through theoretical analysis. By employing a tight-binding model beyond the Dirac cone approximation, the electronic band structure, density of states, dipole matrix elements, and third-order nonlinear optical susceptibilities are calculated. The application of a magnetic field induces a Zeeman splitting of the energy levels, breaking the band degeneracy. Consequently, the dipole matrix elements exhibit a magnetic field dependence, altering the intensity and number of allowed transitions. In the infrared and ultraviolet energy regions, the linear optical absorption spectrum displays the splitting of peaks into dual neighboring peaks, with the splitting distance linearly dependent on the magnetic field strength. The third-order nonlinear optical susceptibilities, χTHG(3)3ω and χIDIR(3)ω, reveal the emergence of multiple resonance peaks in different energy regions due to two-photon and three-photon absorption processes. The magnetic field significantly influences the number, position, and height of these optical peaks, enabling effective control over the nonlinear optical response. By investigating the scaled energy (E/E_g) dependence, a universal behavior is observed for the three- and two photon resonance peaks, where their positions remain constant, but their peak intensities are significantly enhanced under the influence of the magnetic field. These findings demonstrate the potential of GeNTs as tunable nonlinear optical materials, with the magnetic field serving as an effective parameter for engineering their optical properties for various applications in optoelectronics, photonics, and related fields.

Population Pharmacokinetic Analysis of Tucatinib in Healthy Participants and Patients with Breast Cancer or Colorectal Cancer.

Tucatinib is a highly selective, oral, reversible, human epidermal growth factor receptor 2 (HER2)-specific tyrosine kinase inhibitor. Tucatinib is approved at a 300-mg twice-daily dose in adults in combination with trastuzumab and capecitabine for advanced HER2-postitive (HER2+) unresectable or metastatic breast cancer and in combination with trastuzumab for RAS wild-type HER2+ unresectable or metastatic colorectal cancer. This study sought to characterize the pharmacokinetics (PK) and assess sources of PK variability of tucatinib in healthy volunteers and in patients with HER2+ metastatic breast or colorectal cancers. A population pharmacokinetic model was developed based on data from four healthy participant studies and three studies in patients with either HER2+ metastatic breast cancer or metastatic colorectal cancer using a nonlinear mixed-effects modeling approach. Clinically relevant covariates were evaluated to assess their impact on exposure, and overall model performance was evaluated by prediction-corrected visual predictive checks. A two-compartment pharmacokinetic model with linear elimination and first-order absorption preceded by a lag time adequately described tucatinib pharmacokinetic profiles in 151 healthy participants and 132 patients. Tumor type was identified as a significant covariate affecting tucatinib bioavailability and clearance, resulting in a 1.2-fold and 2.1-fold increase in tucatinib steady-state exposure (area under the concentration-time curve) in HER2+ metastatic colorectal cancer and HER2+ metastatic breast cancer, respectively, compared with healthy participants. No other covariates, including mild renal or hepatic impairment, had an impact on tucatinib pharmacokinetics. The impact of statistically significant covariates identified was not considered clinically meaningful. No tucatinib dose adjustments are required based on the covariates tested in the final population pharmacokinetic model. NCT03723395, NCT03914755, NCT03826602, NCT03043313, NCT01983501, NCT02025192.

Enhancing Photothermal Energy Transduction through Inter- and Intramolecular Interactions of Multiple Two-Photon Dyes Appended onto Calix[4]arene.

Organic dyes-based photothermal agents (OPTAs) have received increasing attention as alternative to inorganic materials due to their higher biocompatibility and extensive diversification. Maximizing nonradiative deexcitation channels is crucial to improve the photothermal conversion efficiency (PCE) of OPTAs. This is typically achieved through individual molecular design or collective enhancement using supramolecular strategies. Furthermore, photothermal therapy (PTT) generally relies on linear one-photon absorption of the light source by the OPTA, with less consideration given to nonlinear two-photon absorption (2PA) strategies, despite their potential benefits. Here, a synergistic strategy, which combines intramolecular and intermolecular quenching, is employed to maximize the photothermal efficiency of diphenylamino-substituted distyryl dicyanobenzene (DSB), an outstanding two-photon-absorbing chromophore. One to three DSB units have been introduced on the conic p-tert-butyl-calix[4]arene (CX), serving as a preorganizing platform to allow aggregate formation and promote intramolecular quenching within the multichromophoric systems. Importantly, the multichromophoric molecules had very high two-photon absorption capabilities with cross sections (δ2PA) reaching maximal values of 3290 GM at 810 nm. Experimental data accompanied by large-scale molecular dynamics simulations and time-dependent density functional theory calculations shed light onto the interaction mechanism in those multiple DSB-appended CX compounds to rationalize their optical properties. Then, the formulation with Pluronic F127 amphiphile yields water-dispersible nanoprecipitates (Nps), in which the PCE is further maximized and the photobleaching is reduced due to the combination of intra- and intermolecular quenching. The high two-photon absorption in the near-infrared (NIR) window associated with the high PCE of these nanosized OPTAs could serve as a basis to future in vivo 2P-PTT applications.

Delta-doping modulation of three quantum wells under the influence of an electric field

The impact of delta-doping modulation and electric field influence within a nanostructure consisting of three GaAs quantum wells (QWs) separated by AlGaAs barriers was investigated. The quantized energy levels, Fermi energy, wavefunctions, self-consistent potential, and electron density distribution were evaluated by a self-consistent solution of the Schrödinger and Poisson equations using the finite element method within the FEniCS project in Python. The results indicate that increasing the electric field reduces energy levels and Fermi energy. In addition, the delta-doping position and electric field significantly affect the self-consistent potential and electron density distribution. This study provides a possibility to tailor optical properties, such as the linear absorption coefficient and photoluminescence, by adjusting geometrical and non-geometrical parameters, including donor density, enhancing the functionality of doped QWs in designing high electron mobility transistors.

Optical Limiting Methods by Z-Scan Technique for Non-Linear Optical Absorption of PVC/TiO2 Nanocomposite

To further our grasp of photonics technology, our work focuses on thin-film PVC/TiO2 nanocomposites. Nanocomposites composites were created by combining TiO2 nanoparticles with Polyvinyl Chloride (PVC) as the polymer matrix. The thin film was fabricated using the casting method. Spectral analysis was used to determine the absorbance parameters and compute the linear absorption coefficient. The nonlinear refractive index and nonlinear absorption coefficient were measured using a single beam Z-scan approach with a CW diode pumped solid state (DPSS) laser (Coherent Verdi-V5, 532 nm) acting as the excitation laser at 50mW. Peak absorption was measured at 280 nm, and as the percentage of TiO2 nanoparticles grew, more absorption was seen. The nonlinear absorption coefficient was determined to be 1x10−5 cm/W at (0.5342, 1.3585, 1.5999, and 0.0253). The poor structure arising from all of the sample morphologies affects the materials' NLO absorption. Nonetheless, they seem like good options for optical limiting applications given the positive value of NLO absorption.

Determination of gelatin from marshmallows using a combination of fourier transform infrared (ATR-FTIR) spectroscopic and chemometrics for halal authentication

Marshmallow is a foam that contains aerated sugar, which is stabilized with gelatin or egg albumin. In this research, a Fourier Transform Infra-Red (ATR-FTIR) spectroscopy combined with the Chemometrics methods is developed to distinguish the presence of porcine gelatin in marshmallows, which can then be used to identify halal products. This method provides fast and rapid testing of halal products. Marshmallows were made with varying concentrations of bovine and porcine gelatine as the reference. Commercial marshmallows were collected in the online marketplace by purposive sampling. Isolated gelatin was analyzed using the ATR-FTIR spectrophotometer, and data analysis was continued using PCA (Principal Component Analysis). The results showed that bovine gelatin absorbed at a wavenumber of 1638 cm-1, while porcine gelatin produced a sharp absorption at 1697 and 1654 cm-1. The results of PCA analysis show that 100% of bovine gelatin marshmallows (S100) have areas different from marshmallows containing a mixture of porcine gelatin. The PCA results of four samples (A1, A2, A3, and A4) show they are in the same area as 100% bovine gelatin marshmallows (S100). This shows that it is suspected that the four marshmallow samples tested did not contain porcine gelatin. The multivariate regression curve showed that the pattern of linear absorbance changes along with porcine gelatin concentrations with the highest coefficient equation is from wavenumber 1093.97 cm-1. Keywords: ATR-FTIR, Bovine gelatin, Chemometric, Marshmallow, Porcine gelatin