Raman Spectroscopy Techniques Research Articles

High cycling stability polyaniline/carbon sphere/graphene ternary nanocomposite cathode material for asymmetric supercapacitors

Here, an asymmetric supercapacitor of the ternary nanocomposite polyaniline/carbon sphere/graphene (PANI/CS/G) is developed through a green strategy via the in-situ polymerization of aniline in carbon sphere/graphene (CS/G) dispersion prepared in a ball-mill method coupled with hydrothermal treatment. A strong interaction and thus the coverage of CS/G with PANI is revealed from the material characterization using XRD, FTIR and Raman spectroscopic techniques, and also from FESEM and HRTEM images. Uniform distribution of PANI over the CS/G provided an effective conducting network and enhanced diffusion of the electrolyte ions. PANI/CS/G showed a specific capacitance of 145.02 mF/cm2 at a current density of 1 mA/cm2 in 1 M H2SO4 originating from the electrostatic double layer capacitance behavior of the CS/G and pseudocapacitance of PANI. The fabricated asymmetric coin cell device with PANI/CS/G cathode and CS/G anode showed the highest areal capacitance of 320.78 mF/cm2 (@ 1 mA/cm2), a maximum energy density of 18.99 Wh/kg (@ 0.21 A/g), and a highest power density of 6088.48 W/kg (@ 8.68 A/g). The device displayed 101.6 % capacitance retention after 10000 cycles, indicating the effect of CS/G in diminishing the volume changes of PANI during the charge-discharge process, which usually affects the cyclic stability. By lighting a green LED, the real sense energy storage application of the supercapacitor is evaluated.

Dynamic Detection of Decomposition Gases in Eco-Friendly C5F10O Gas-Insulated Power Equipment by Fiber-Enhanced Raman Spectroscopy.

Dynamic detection of multiple C5F10O decomposition gases can more comprehensively and effectively evaluate the operating status of eco-friendly gas-insulated power equipment (GIPE), which is a technical support for promoting the construction of eco-friendly, low-carbon energy power systems. In this article, we propose a silicon noise suppression fiber-enhanced Raman spectroscopy (FERS) technique and design a FERS sensing system for the dynamic detection of multiple C5F10O decomposition gases. Benefiting from the effective hybrid silicon noise filtering technology, the spectrum noise of FERS can be suppressed by 90% and the system detection sensitivity can be improved by 4.22 times. Utilizing a 2 m-long antiresonant hollow-core fiber, the system achieved detection limits of 1.34 and 1.44 ppmv for CF4 and CO2, respectively, under the conditions of a laser power of 200 mW, a pressure of 0.5 MPa, and a measurement time of 120 s. Afterward, combining sample gas and density functional theory simulation, the characteristic peak positions for quantitative analysis of C5F10O decomposition gas were determined as follows: CF4: 906 cm-1, CO2: 1388 cm-1, C5F10O: 759 cm-1, CF2O: 965 cm-1, CF3H: 1117 cm-1, C2F4: 517 cm-1, C2F6: 807 cm-1, C3F6: 767 cm-1, C3F8: 780 cm-1, C3F7H: 857 cm-1, and C4F10: 770 cm-1. Finally, the sensing system conducted dynamic measurements of the partial discharge decomposition gases of the C5F10O GIPE for 5 days with a 2 h measurement interval. The content trends of C5F10O and decomposition gases CF4, CO2, C3F6, and C3F7H were obtained. These results fully demonstrate the capability of FERS technology for dynamically detecting the decomposition gases of the C5F10O GIPE.

Dual LSPR and CT synergy: 3D urchin-like Au@W18O49 enables highly sensitive in-situ SERS detection of dissolved furfural in insulating oils

Assessing the levels of furfural in insulating oils is a crucial technical method for evaluating the degree of aging and mechanical deterioration of oil-paper insulation. The surface-enhanced Raman spectroscopy (SERS) technique provides an effective method for enhancing the sensitivity of in-situ detection of furfural. In this study, a homogeneous three-dimensional (3D) urchin-like Au@W18O49 heterostructure was synthesized as a SERS substrate using a straightforward hydrothermal method. The origin of the superior Raman enhancement properties of the 3D urchin-like heterostructures formed by the noble metal Au and the plasmonic semiconductor W18O49, which is rich in oxygen vacancies, is analyzed experimentally in conjunction with density-functional theory (DFT) calculations. The Raman enhancement is further amplified by the remarkable dual localized surface plasmon resonance (LSPR) effect, which generates a strong local electric field and creates numerous "hot spots," in addition to the interfacial charge transport (CT). The synergistic effect of these factors results in the 3D urchin-like Au@W18O49 heterostructure exhibiting exceptionally high SERS activity. Testing the rhodamine 6G (R6G) probe resulted in a Raman enhancement factor of 3.41 × 10−8, and the substrate demonstrated excellent homogeneity and stability. Furthermore, the substrate was effectively utilized to achieve highly sensitive in-situ surface-enhanced Raman scattering (SERS) detection of dissolved furfural in complex plant insulating oils. The development of the 3D urchin-like Au@W18O49 heterostructure and the exploration of its enhancement mechanism provide theoretical insights for the advancement of high-performance SERS substrates.

Spectroscopic, vibrational and structural insights into LaYbO3:Pr3+ and LaLuO3:Pr3+,Tb3+ perovskites at ambient and high-pressure conditions

The interlanthanide perovskites LaYbO3:Pr3+ and LaLuO3:Pr3+,Tb3+ were synthesized by a solid-state reaction and characterized at ambient conditions by means of X-ray diffraction (XRD), Raman spectroscopy and photoluminescence techniques. XRD measurements have shown that the synthesis method provided samples with pure perovskite phase (space group Pnma) for LaYbO3, while in the case of the LaLuO3 compound small traces of Lu2O3 could be found after several annealing. Up to 13 Raman active modes were observed in the Raman spectra of the studied perovskites and theoretical calculations performed for LaYbO3 allowed to assign their symmetry. Regarding their optical properties, the emission from Tb3+ ions at B sites of the ABO3 perovskite could be distinguished. Moreover, NIR emission from Pr3+ was observed in the LaLuO3 perovskite at ∼1000 nm and 1250-1600 nm. Emission in these spectral regions could be relevant for Si-based solar cell applications and fiber optic amplifiers, respectively. Moreover, the stability of both perovskites under high-pressure conditions has been studied spectroscopically, finding that LaYbO3 is stable up to 19 GPa and that LaLuO3 undergoes a possible pressure-induced phase transition at ∼21-24 GPa. This makes LaLuO3 the first interlanthanide perovskite showing phase transition under 40 GPa.

Insights into Chemical Aging of Urban Aerosols over Delhi, India

Atmospheric particles can undergo aging as they are transported over long distances and mix with particles from other sources. This can lead to the accumulation of pollutants and the formation of complex aerosol mixtures with diverse chemical and physical properties. To investigate the process of aging in ambient atmosphere, 24h sampling of PM2.5 aerosol particles on Quartz microfiber filter with a tin substrate was carried out from November 2020 to March 2021 at CSIR-National Physical Laboratory, New Delhi (28°38'10″ N and 77°10′17" E), using fine particle sampler. Based on the observations of weather and meteorological parameters, a few episodic cases have been selected, and samples were analyzed at bulk and individual particle level. The objective of the present study is to investigate the aging characteristics of aerosols, enabling us to understand the mixing of aerosols (at both bulk and individual particle levels) and the variation in fresh and deformed (aged with other species) graphitic content in the episodic cases. The Raman Spectroscopy technique employed measures the intensity of graphitic (G band; around 1580 cm-1) and disordered graphitic (D band; around 1320 cm-1) content of aerosols. Individual particle microscopic observations reveal the occurrence of open chain fractals of black carbon in variable monomer sizes, sometimes agglomerated with metals like Cu, Cr, Ca etc., along with the presence of S- rich and organic aerosols while the Raman Spectrum (bulk sample analysis) highlights graphitic and disordered (when graphite interacts with other chemical species) graphitic intensities. Comparing the intensities of heavy haze and moderate haze with non-haze days (for comparison purpose, March 23, 2021 with the lowest PM2.5 concentration ∼ 62 μg m−3, has been considered as a non-haze day), it was observed that the intensities recorded on haze days were 45 to 200 times higher for the G band and 43 to 93 times higher for the D band; while for moderate haze days, the intensities were 4 to 61 times higher for the G band and 2 to 29 times higher for the D band. These findings suggest chemical processing of BC during haze days.

Effect of Fe2O3 on CeO2 films in the photocatalytic evaluation towards the degradation of brilliant green and oxytetracycline

This paper presents a photochemical synthesis method for producing pure CeO2 deposits and CeO2 deposits loaded with varying proportions of Fe2O3. The deposits were calcined at 950 °C and characterized structurally, compositionally, and morphologically using XRD, XPS, SEM, FT-IR, and Raman spectroscopy techniques. Cerianite and hematite phases were identified in CeO2/Fe2O3 samples, indicating heterogeneous surface deposits. Photocatalytic testing under UV–Vis illumination for 5 h demonstrated promising results. For the degradation of bright green dye, efficiencies of 78.9 % and 90.1 % were achieved for pure CeO2 and CeO2 samples loaded with 1.0 mol% Fe2O3, respectively. Similarly, for oxytetracycline drug degradation, performance rates of 35.3 % and 67.0 % were observed for CeO2 and CeO2 samples loaded with 1.0 mol% Fe2O3, respectively. Recyclability tests showed a gradual decline in photocatalytic performance over successive cycles due to by-product accumulation contaminating the catalyst.

Facile coupling of plasmonic Au-NPs on ZnS NFs as a robust SERS substrate for toluidine blue detection and degradation

BackgroundThe robustness and sensitivity of the surface-enhanced Raman spectroscopy (SERS) technique heavily relies on the development of SERS active materials. A hybrid of semiconductor and plasmonic metals is highly effective as a SERS substrate, which enables the trace level detection of various organic pollutants. ResultsThis approach demonstrates the photodeposition of plasmonic gold nanoparticles (Au-NPs) on the surface of semiconductor-zinc sulfide nanoflowers (ZnS NFs), grown via the hydrothermal route. The synergistic contribution of the charge-transfer phenomenon and localized surface plasmon resonance of the Au-NPs/ZnS NFs makes it an ideal SERS substrate for the detection of organic pollutants, toluidine blue (TB). The proposed material has a high SERS enhancement factor (109), low limit of detection (10−11 M), good reproducibility, selectivity and strong anti-interference ability. Furthermore, the practicability of the Au-NPs/ZnS NFs is explored in real-time water samples, which are obtained with the satisfactory recovery rates. Additionally, the UVC light illumination on the Au-NPs/ZnS NFs has efficiently degraded TB within a time period of 150 min. Significance and noveltyThese finding demonstrate the significance of the proposed Au-NPs/ZnS NFs for SERS based detection and degradation of organic pollutants in real-time samples, highlighting their potential in monitoring and treating water pollutants in wastewater.

Research Progress of Raman Spectroscopy and Imaging Techniques for the Pharmaceutical Analysis

Research Progress of Raman Spectroscopy and Imaging Techniques for the Pharmaceutical Analysis

Near-infrared excitation Raman spectroscopy of colored fabric contaminated with body fluids

Confirmatory identification of dyes in the physical pieces of evidence, such as hair and fabric, is critically important in forensics. This information can be used to demonstrate the link between a person of interest and a crime scene. High performance liquid chromatography is broadly used for dye analysis. However, this technique is destructive and laborious. This problem can be overcome by near-Infrared excitation Raman spectroscopy (NIeRS), non-invasive and non-destructive technique that can be used to determine chemical structure of highly fluorescent dyes. Analyzed fabric materials often possess body fluid stains, which may obscure the accuracy of NIeRS-based identification of dyes. In this study, we investigate the extent to which fabric contamination with body fluids can alter the accuracy of NIeRS. Our results showed that NIeRS coupled with partial-least squared discriminant analysis (PLS-DA) enabled on average 97.6% accurate identification of dyes on fabric contaminated with dry blood, urine and semen. We also found that NIeRS could be used to identify blood, urine and semen on such fabric with 99.4% accuracy. Furthermore, NIeRS could be used to differentiate between wet and dry blood, as well as reveal the presence of blood on washed fabric. These results indicate that NIeRS coupled with PLS-DA could be used as a robust and reliable analytical approach in forensic analysis of fabric.

Novel electrochemical sensing platform based on zinc metal organic frameworks/carbon nanofiber nanocomposite for detection of creatinine in human urine

A biomarker known as creatinine is a very important determinant of kidney failure. Creatinine concentrations in blood and urine can identify renal insufficiencies and muscle diseases. Monitoring the creatinine level and quick sensing requires a rapid, robust and simple method for determining the creatinine in human body. To overcome the universal challenge postured by this waste product of muscle, this study presents a novel strategy to fabricate an electrochemical sensor based on zinc MOFs, synthesized using terephthalic di- hydrazide (TPDD) as the organic ligand using a one-pot solvothermal method in the presence of carbon nanofiber matrix for enzyme less sensing the creatinine. The Zn-TPDD/CNF nanocomposite was well characterized by XRD, TGA, BET, XPS, FESEM, CV, DPV, and Raman spectroscopic techniques. Notably, this MOF anchored electrode owns important fundamental features such as large electro active exterior area, plentiful active sites, an immense operational linear range (5 to 250 μM), a nominal detection limit (10.04 nM), and an outstanding sensitivity towards creatinine. This Zn-TPDD/CNF/GCE electrode not only showcased more extraordinary electrochemical attributes, but its anti-interference stability, flexibility, reproducibility, storage stability, selectivity, and low detection threshold emphasize its ability for real-world applications with reasonable recoveries. Therefore, this modified electrode could be a potential tool for operative creatinine detection in urine.

Raman spectroscopy - a visit to the literature on plant, food, and agricultural studies.

Raman spectroscopy, a fast, non-invasive, and label-free optical technique, has significantly advanced plant and food studies and precision agriculture by providing detailed molecular insights into biological tissues. Utilizing the Raman scattering effect generates unique spectral fingerprints that comprehensively analyze tissue composition, concentration, and molecular structure. These fingerprints are obtained without chemical additives or extensive sample preparation, making Raman spectroscopy particularly suitable for in-field applications. Technological enhancements such as surface-enhanced Raman scattering, Fourier-transform-Raman spectroscopy, and chemometrics have increased Raman spectroscopy sensitivity and precision. These and other advancements enable real-time monitoring of compound translocation within plants and improve the detection of chemical and biological contaminants, essential for food safety and crop optimization. Integrating Raman spectroscopy into agronomic practices is transformative and marks a shift toward more sustainable farming activities. It assesses crop quality - as well as the quality of the food that originated from crop production - early plant stress detection and supports targeted breeding programs. Advanced data processing techniques and machine learning integration efficiently handle complex spectral data, providing a dynamic and detailed view of food conditions and plant health under varying environmental and biological stresses. As global agriculture faces the dual challenges of increasing productivity and sustainability, Raman spectroscopy stands out as an indispensable tool, enhancing farming practices' precision, food safety, and environmental compatibility. This review is intended to select and briefly comment on outstanding literature to give researchers, students, and consultants a reference for works of literature in Raman spectroscopy mainly focused on plant, food, and agronomic sciences. © 2024 Society of Chemical Industry.

(Invited) Tunable Infrared Optoelectronics Achieved by the Reversible Intercalation of Ionic Liquid Anions in Multilayer Graphene in the Mid-Infrared Wavelength Range

We report the use of multilayer graphene (MLG) grown by chemical vapor deposition (CVD) approximately 75 layers (26 nm) thick configured in a simple electrochemical device. Applying a voltage of 3–4 V drives the intercalation of anion [TFSI-] (ion liquid diethylmethyl(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide [DEME][TFSI]]) resulting in the reversible modulation of the properties of this optically dense material. Upon intercalation, we observe an abrupt shift of 35 cm−1 in the G band Raman mode, an abrupt increase in FTIR reflectance over the wavelength range from 1.67 to 5 μm (2000–6000 cm−1 ), and an abrupt increase in luminescent background observed in the Raman spectra of graphene. All of these abrupt changes in the optical properties of this material arise from the intercalation of the TFSI− ion and the associated change in the free carrier density (Δn = 1021 cm−3). Suppression of the 2D band Raman mode observed around 3 V corresponds to Pauli blocking of the double resonance Raman process and indicates a modulation of the Fermi energy of ΔEF= 1.1 eV. The thermal emissivity of the MLG device is also substantially modulated over the range from 7 – 14 µm. Using this device, have demonstrated free-space optical communication that utilizes ambient Planck radiation from a warm body and modulates the emitted intensity. We present an experimental demonstration achieving error-free communications at 100 bits per second over laboratory scales. We have also developed an AC Raman technique for measuring the Raman spectra during the intercalation−deintercalation half cycles in a multilayer graphene (MLG) device operating at 0.2−10 Hz. Raman spectra taken just 200 ms apart show the emergence and disappearance of the intercalated G band mode at around 1610 cm−1 . By integration of over hundreds of cycles, a significant Raman signal can be obtained. The intercalation/ deintercalation is also monitored with thermal imaging via voltage-induced changes in the carrier density, complex dielectric function ε(ω), and thermal emissivity of the device. “Dynamic Study of Intercalation/Deintercalation of Ionic Liquids in Multilayer Graphene Using an Alternating Current Raman Spectroscopy Technique” Zhi Cai, Haley Weinstein, Indu Aravind, Ruoxi Li, Sizhe Weng, Boxin Zhang, Jonathan L. Habif, and Stephen B. Cronin. Journal of Physical Chemistry Letters, 14, 7223 (2023).“Gate-tunable modulation of the optical properties of multilayer graphene by the reversible intercalation of ionic liquid anions” Zhi Cai, Indu Aravind, Haley Weinstein, Ruoxi Li, Jiangbin Wu, Han Wang, Jonathan Habif, and Stephen Cronin. Journal of Applied Physics. 132, 095102 (2022).“Harvesting Planck radiation for free-space optical communications in the long-wave infrared band“ Haley A. Weinstein, Zhi Cai, Stephen B. Cronin, and Jonathan L. Habif, Optics Letters. 47, 6225-6228 (2022). Figure 1

Influence of graphene nanoplatelets on the thermal conductivity of heat transfer oils based on the developed hotwire method

The thermal conductivity measurements of graphene nanoplatelets (GNP) loaded mineral oil suspensions are obtained using an unconventional custom-made Transient Hot-Wire setup using tungsten. The presence of a few layers of graphene in the prepared GNP using a single-step ultrasonication of graphite microparticles without the use of a surfactant is verified by AFM, TEM, Raman Spectroscopy, XRD, and XPS techniques. We measured the thermal conductivity and the specific heat capacity ( Cp ) of GNP-loaded mineral oil suspensions. The experimental result shows a maximum of 45.5% increment in the thermal conductivity of the mineral oil with 1 mg ml−1 (11.481 ×10−4 weight fraction) loading of GNP at 30 °C. Despite thermal conductivity enhancements, the results indicate that the Cp is not compromised, since a low concentration of nanoplatelets was used. The experimental results agree with the Maxwell-Garnett effective medium approach (MGEMA) model for the thermal conductivity of nanofluids which we found to be suitable for lower loading of nanoparticles. We propose GNP incorporated mineral oil suspensions are effective when it comes to heat transfer fluids even with the lower volume and mass fractions.

Synthesis of Zn2+:LaMnO3 perovskites nanoparticles by facile co-precipitation approach: Physicochemical characteristics and supercapacitor application

This work has examined the impact of Zn2+ on the crystal architecture and electrochemical functionality of LaMnO3 perovskite nanoparticles. Crystalline parameters of the as-prepared samples were analyzed by X-ray Diffraction studies (XRD). Fourier transform infrared (FT-IR) measurements are utilized to detect the functional groups present in the sample. Raman spectroscopy technique was used to analyze the nature of the chemical bonds in the prepared material. The shape and elemental content of the produced nanomaterials were determined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX). Brunauer-Emmett-Teller (BET) technique is used to study the porosity and surface area of the material. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge/discharge (GCD) is employed to study the surface resistivity, oxidation–reduction potential and super capacitance efficiency of the prepared electrode material.

Low-frequency Raman spectrum of methamphetamine hydrochloride and its alterations induced by impurities

Methamphetamine is one of the most abused drugs worldwide. Forensic laboratories have developed various methods to analyze methamphetamine for identifying and comparing seizures. These methods basically focus on the physicochemical properties of the methamphetamine molecule. Because methamphetamine is commonly distributed in its hydrochloride salt form, information on the crystalline state of methamphetamine could give new insight for forensic drug analysis. To grasp this information, we applied low-frequency Raman spectroscopy to methamphetamine hydrochloride. A laboratory-built low-frequency Raman microspectrometer was used for measuring low-frequency Raman spectra of optically pure and racemic methamphetamine hydrochloride. A mixture of methamphetamine hydrochloride with dimethyl sulfone, which is frequently added as a diluent to illicit methamphetamines, was also measured. An ab initio calculation was performed to assign peaks in the low-frequency spectra. The phonon modes of methamphetamine hydrochloride, and their changes induced by impurities are discussed. To the best of our knowledge, this is the first reported application of low-frequency Raman spectroscopy technique to methamphetamine hydrochloride.

Raman Spectroscopy as an Effective Tool for Assessment of Structural Quality and Polymorphism of Gallium Oxide (Ga2O3) Thin Films.

Raman spectroscopy, a versatile and nondestructive technique, was employed to develop a methodology for gallium oxide (Ga2O3) phase detection and identification. This methodology combines experimental results with a comprehensive literature survey. The established Raman approach offers a powerful tool for nondestructively assessing phase purity and detecting secondary phases in Ga2O3 thin films. X-ray diffraction was used for comparison, highlighting the complementary information that these techniques may provide for Ga2O3 characterization. Few case studies are included to demonstrate the usefulness of the proposed spectroscopic approach, namely the impact of deposition conditions such as metal-organic vapor-phase epitaxy and pulsed electron deposition (PED), and extrinsic elements provided during growth (Sn in the case of PED) on Ga2O3 polymorphism. In conclusion, it is shown that Raman spectroscopy offers a quick, reliable, and nondestructive high-resolution approach for Ga2O3 thin film characterization, especially concerning phase detection and crystalline quality.

Artificial shock wave impact studies on Olivine single crystal - A Raman spectroscopic approach

After the invention of indoor tabletop shock tubes, studies on the impact of low-pressure acoustic shock waves on materials have been sufficiently conducted and found several spectacular phase transitions. However, the acoustic shock wave impact studies on minerals remain unexplored. The floodgates are to be opened by streamlining a systematic approach in bringing out a new era of spectacular findings as more and more minerals are involved in the investigation. Hence, in the present investigation, we have chosen one of the most prominent upper mantle earth minerals of α-Olivine (forsterite-Mg2SiO4) single crystal for the ex-situ shock wave recovery experiment with 2.0 MPa transient pressure. Raman spectroscopic technique has been utilized to examine the crystallographic stability of the title mineral. The observed shock-wave impact results demonstrate that the forsterite remains to be in the crystallized state maintaining the same space group of Pbnm, however, significant changes have been witnessed in the normalized intensity ratio of the characteristic doublet Raman peaks of the forsterite (asymmetry stretching SiO4 (824 cm-1)/symmetry stretching SiO4 (855 cm-1) such that the values are found to be 2.17, 2.27, 1.38, 0.51, and 2.43 against the number of shock pulses of 0, 1, 2, 3 and 4, respectively. It is to be noted that, we have found more pronounced changes in the doublet Raman peak intensity compared to the flat plate accelerator shock compression experiment on forsterite (Tielke et al., J. Geophys. Res. Planets (2022)) and the observed values are 0.8, 0.3, 0.6, 0.8 and 0.52 for 0, 21.3, 22.4, 38.9 and 41.8 GPa, respectively without undergoing any structural transitions towards the high-pressure phases. Based on the assessment of comparative results, tabletop shock-tubes can be strongly considered for mineralogical research to expand the current knowledge on the behaviors of the earth and space minerals under extreme-conditions.

Halide tuning in derivative organic–inorganic perovskites, MAPb(Br1-xClx)3 (x = 0–1): exploring structural, optical and vibrational characteristics

Organic–inorganic metal halide perovskites (OIMHP’s), particularly CH3NH3PbX3 (X = I, Br, Cl) and their derivatives shows favorable properties for energy harvesting such as high absorption coefficients, adjustable band gaps, and low charge recombination rate. The structure and hence nature of bonding between different atoms of these perovskites is known to affect their properties significantly. Tuning of band gap can be achieved in these systems with the help of compositional variation. These systems are studied extensively in the single halide compositions (MAPbI3, MAPbBr3 and MAPbCl3); while, their derivatives seem to have gained less attention though being important for various applications. So, in this work, halide tuning is achieved in derivative perovskite, MAPb(Br1-xClx)3 (x = 0 to 1) and further studied for structural and optical properties along with vibrational properties using X-ray diffraction (XRD), diffuse reflectance spectroscopy, and Raman spectroscopy techniques, respectively. A decrease in the lattice parameter is observed as the Chlorine content increases in the MAPb(Br1-xClx)3 (x = 0 to 1) perovskite. The substitution of Chlorine with Bromine also results in significant increase in the band gap value. In contrast to previous reports, it was clearly observed that the Urbach energy strongly depends on the composition. For the first time, appearance of two features for torsional mode of methylammonium (MA) is discussed even at room temperature, indicative of disorder. It is observed that although the band gap tuning is achieved with the help of halide mixing (Br and Cl), it is also found to introduce disorder in the intermediate compositions; while, the stability increases toward Chlorine compositions. Interestingly, the information of disorder is found to be contained in both the global as well as local measurements which opens up new pathways for studying these materials. This study will lay down a pathway for better understanding of key properties of these hybrid mix halide perovskites which are promising material for futuristic energy applications.

Investigating the synergistic effect of RuO2 nanoparticle-decorated V2O5 nanoflakes for sensitive detection of 2,4-dinitrophenol and 2,4-dinitrotoluene

The dinitroaromatic compounds 2,4-Dinitrophenol (2,4-DNP) and 2,4-Dinitrotoluene (2,4-DNT) are prevalent contaminants in various water sources due to their extensive use in explosive synthesis and other industrial applications. The highly toxic and carcinogenic nature of these compounds poses significant risks to human health and environment, making the development of facile, rapid, cost-effective, and selective detection methods crucial. This research presents the one-step hydrothermal synthesis of RuO2 nanoparticle-decorated V2O5 nanoflakes to fabricate an electrochemical sensor for the detection of 2,4-DNP and 2,4-DNT. The synthesized materials were characterized using XRD, Raman spectroscopy, FESEM, HRTEM, and XPS techniques. The electrochemical behavior of 2,4-DNP and 2,4-DNT was investigated using cyclic voltammetry, square wave voltammetry and chronoamperometry. Under optimized conditions, 2,4-DNP and 2,4-DNT exhibited two reduction peaks corresponding to the nitro-functional groups on the aromatic ring. Notably, the 7 wt% RuO2 in V2O5 nanocomposite-modified glassy carbon electrode (RV7/GCE) demonstrated the lowest detection limits of 1.07 nM and 1.01 nM within the linear dynamic range (LDR) of 5.0 nM–35.0 µM for 2,4-DNP, and 2,4-DNT, respectively. Furthermore, the sensor exhibited excellent reusability and reproducibility, delivering consistent results for both laboratory-controlled and real-world samples. This advancement offers efficient detection and monitoring of these hazardous compounds in environmental and industrial settings.

Identification of Delorazepam in Suspected Methaqualone Contraband:A Case Study

The present case study reports the analysis of seized narcotic drug received from investigation agency in Mumbai. The drug was suspected to be methaqualone which falls under NDPS act 1985. Analysis of the drug was carried out using HPTLC, GC-MS, UV and Raman spectroscopy techniques. These complimentary techniques revealed and confirmed the presence of delorazepam in the suspected sample while methaqualone was found to be absent. The case study highlights the importance of analytical techniques in identifying the narcotic drug in the seized sample.