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We report herein the synthesis of ZnFeThe online version contains supplementary material available at 10.1007/s11664-022-09813-2.

Here, in the present report, an attempt has been made to explore a quantitative correlation between the Urbach energy (EU) and the dielectric constant (e) by using a Bohr-like model for Cr-substitu...

The effect of La-doping on the crystallographic structure and the Raman line-shape of CeO2 has been investigated. X-ray diffraction analysis suggests that the lattice parameter and the Ce/La–O bond...

The polycrystalline powder samples of PrCrO3 have been prepared using conventional solid-state synthesis method. Structural investigations are carried out using Raman spectroscopy and synchrotron X-ray diffraction (SXRD) followed by Rietveld refinement of diffraction data. Investigations of diffraction data suggest that these samples possess centrosymmetric orthorhombic structure with space group $$Pnma$$ $$(or\;Pbnm)$$ . The valence (charge) state of Cr in PrCrO3 has been determined from X-ray absorption near edge spectroscopy (XANES). Optical properties are studied using diffuse reflectance spectroscopy technique. Optical absorption study reveals that absorption in PrCrO3 ceramic is dominated by d–d electrons of chromium cation (Cr3+). The synthesized compound found to have energy bandgap of 3.20 eV. Based on the results observed, energy level diagram for PrCrO3 has been presented. High dielectric permittivity $$(\varepsilon {^{\prime}})$$ of the order $$3\times {10}^{3}$$ is observed for the studied sample. Impedance spectroscopy measurement at room temperature on sintered pellet indicates electronic inhomogeneity in the samples as demonstrated by the presence of dielectric relaxation processes associated with highly conducting grain and low conducting grain boundaries. The relaxation mechanism has been explained on the basis of Cole–Cole model. Observed high dielectric permittivity $$(\varepsilon {^{\prime}})$$ and optical energy bandgap $$({E}_{g})$$ indicates that PrCrO3 may find promising application in optoelectronic devices.

This Tutorial provides a fundamental discussion on the lattice dynamics of physical systems introduced with disorder and, hence, the importance of Raman spectroscopy (RS) technique to probe these impacts. The article first discusses, analytically, the impact of disorder on the symmetry allowed phonon modes of the system by considering the finite probability of discrete-continuum interference in terms of electron–phonon interactions in the system, thereby briefly discussing the relevant experimental reports, followed by providing an ephemeral description on the loss of translational symmetry in the lattice environment under the strain field generated due to disorder and its consequence as relaxation of the [Formula: see text] selection rule in terms of RS; thus, correlating these discussions with the observation of the symmetry-forbidden disorder induced phonon modes. The same is also elaborated with the experimental reports on various systems of ABO3 and AO2 kinds, where A and B are cations that exhibit the occurrence of disorder induced phonon modes in the respective Raman spectra because of the disorder introduced into the host lattice, and which is emphasized to be not originating due to any structural phase transitions.

In order to investigate the possible effect of inter-granular strain on the physical properties of Barium titanate (BaTiO3), comparative studies have been carried out on the polycrystalline pellet and its corresponding powder samples. For this purpose, the polycrystalline pellet sample of BaTiO3 has been prepared via conventional solid-state reaction route and powder is obtained by crushing the part of the prepared BaTiO3 pellet. The comparative room temperature structural studies, temperature dependent optical and Raman spectroscopy measurements have been carried out on the prepared pellet and powder samples. Room temperature X-ray diffraction and Raman analysis confirms the presence of extra amount of strain in pellet sample compared with that of the powder sample. Temperature dependent Raman analysis also suggests the difference in the high temperature tetragonal to cubic transition temperature in both cases. Temperature dependent optical absorption properties measured in terms of Urbach energy (EU), Urbach focus (E0) and Urbach relaxation clearly indicates the significant change in these quantities for both types of samples on BaTiO3. Present results strongly reveal the difference in structural, optical and vibrational properties of BaTiO3 especially across phase transition in pellet and its corresponding powder which clearly shows the importance of inter-granular strain at the grain boundaries.

In this report, the isothermal time-dependent Raman scattering study has been used to investigate the origin of the cluster glass state in samarium orthoferrites (SmFeO3) via probing selective dyna...

Here we introduce a way to understand the phenomena of localization/delocalization of excitons experimentally as well as by first-principle study. Using in-situ temperature-dependent optical absorption spectroscopy (TD OAS), variation of delocalization parameter (ξ) and electronic disorder in terms of Urbach energy as a function of temperature was estimated. For this purpose, polycrystalline samples of PrFe1−xCrxO3 (x = 0 to 0.25) were synthesized via wet chemical method. The ξ increased with inclusion of Cr doping, which could be understood in terms of an increase in delocalized nature of excitons. Further, the theoretically simulated optical absorption spectrum for undoped and Cr-doped PrFeO3 clearly indicated the change in excitonic peak from almost Gaussian to Lorentzian nature and was explained in terms of an increase in delocalized nature of excitons with inclusion of Cr doping. Thus, using the combination of TD OAS and first-principle calculations, we demonstrated a way to acquire precise information about exciton dynamics, which could be very helpful in understanding many interesting phenomena such as electron–phonon coupling, electronic disorder near band edge and transport properties.

Electrochromic performance of an inorganic–organic layered blend consisting of prussian blue and ethyl viologen has been studied in the form of a device designed to test its performance as well as identify the working mechanism. Initially the sky-blue colored device, consisting of prussian blue and ethyl viologen electrodes, switches reversibly between transparent and dark blue states on application of electrical bias of up to 1.5 V with appropriate polarity. Raman spectroscopic and electrochemical investigations along with control experiments very clearly suggest that reversible redox switching of the two species are responsible for the electrochromism in the device. The fabricated device shows a good optical modulation of more than 50% in dual wavelength region of 400 and 600 nm (blue and red), serving as dual wavelength filter, while maintaining its optical durability for more than 8400 s (1400 pulses) with high coloration efficiency. The inorganic–organic hybrid device comprised of prussian blue and e...

The composition dependent dielectric and optical absorption measurements have been carried out on polycrystalline samples of PrFe1-xCrxO3 (x = 0 to 0.20) in order to investigate the possible correlation between (i) dielectric loss; defined in terms of loss tangent (tanδ) (ii) optical band gap (Eg) and (iii) width of electronic disorder i.e. Urbach width (Eu). It has been observed that with increasing Cr doping, the value of tanδ and Eu increases systematically whereas; systematic decrease in Eg has been observed. It appears that the decrease in the value of Eg and increase in value of Eu leads to an increase in the tunnelling probability of electron from valence band to the conduction band which may result in increase in the value of tanδ. Present investigations strongly suggest that there must be a direct correlation between dissipation factor and electronic disorder term i.e. Urbach energy. Here, a completely new way has been established in order to understand the possible correlation between the dielectric loss, band gap and Urbach energy terms in the form of tunnelling probability. Thus, using the combination of dielectric and optical spectroscopy measurements, a new mechanism has been proposed and demonstrated to understand the origin of dielectric loss in highly correlated electron systems in present work.

The classical ferroelectric material BaTiO3 has been doped with large cation i.e., Hf at Ti site in order to understand the effect of structural disorder in electronic and phononic state. The Raman spectroscopy measurement on these samples indicates increase in the structural disorder with Hf doping. The detail analysis of the Raman spectroscopy data clearly suggests the appearance of new Raman mode at ~ 780 cm−1 and the presence of an asymmetry in almost all Raman modes. The appearance of new Raman mode has been attributed due to the structural disorder induced phonon modes; and this is further confirmed using laser irradiation studies. Additionally, it has been observed that the intensity of this new phonon mode increases systematically with Hf doping; indicating increase in the phononic disorder. It has been observed that the line shape Raman phonon modes show significant asymmetry and this asymmetry along with the full peak width at half maxima (FWHM) of Raman phonon mode shows systematic variation with Hf doping. The observed asymmetric Raman line profile has been analysed through Fano model of electron–phonon coupling which suggests an increase in the electron–phonon coupling with Hf doping. In order to get further insight on increase in the electron–phonon coupling near band edge optical absorption spectroscopy measurements has been carried out and value of electronic disorder in the form of Urbach energy has been estimated and the same is observed to scale with Hf doping. Thus, the systematic increase in the intensity of disorder phonon mode and that of electronic disorder has been observed. This suggests that structural disorder not only affects phonons but electronic state of the system as well. Thus, it appears that the increase in the width of electronic and phononic disorder may overlap in energy scale and may be responsible for the observed increase in the electron–phonon coupling parameter as estimated through Fano equation.

Effect of Hf doping at Ti site in BaTiO3 on the optical band gap (Eg), Urbach energy (Eu), dielectric constant (e) and dielectric loss i.e. loss tangent (tanδ) have been investigated. It has been observed that with Hf doping, the value of Eg and Eu systematically increases whereas; the value of dielectric constant and dielectric loss systematically decreases. The decrease in the value of dielectric constant has been explained in terms of reduction in the tetragonality i.e. by c/a ratio. In the present investigation, it has been proposed that increase in the value of Eg and Eu, leads to decrease in the tunneling probability of electron from valence band to the conduction band which may result in decrease in the value of the dielectric loss. Present investigations clearly suggest that the value of dielectric loss is effectively controlled by Eg. Thus, through present studies, a new methodology has been proposed for understanding the origin of dielectric loss. Moreover, a possible correlation between the Eg and tanδ in terms of tunneling probability has been provided.

We investigate the nature of bond disproportionation in $$\hbox {BaBi}_{0.9}\hbox {Y}_{0.1}\hbox {O}_{3}$$ (BYBO) and its manifestation in the valence band and the optical absorption spectra. Our room-temperature (RT) structural results show that both the parent and the doped (BYBO) compounds stabilise in monoclinic structure but with a change in space group from I2/m to P21/n on Y doping. The Raman scattering studies suggest decrement in the breathing mode distortion of $$\hbox {BiO}_{6}$$ octahedra. The valence band spectra show an increase in the gap and close to the Fermi edge, we observe significant modifications in the fine structures on Y doping. These were studied using band structure calculations under TB-mBJ. The results show that the electronic states of the Y ions play significant role in driving the electronic structure. We also observe the importance of O 2p holes and also transfer of electrons from O 2p to Bi1 6s, Bi2 6s, and Y states to bring about bond disproportionation in the doped compound. The intensity variations and the features in the optical absorption spectra were understood based on the E vs k point calculations performed in the irreducible part of the Brillouin zone. The behaviour of the gap on doping is also in line with the calculations and optical absorption studies. The behaviour of the optical absorption spectra suggests possible use in solar cell and optical sensor applications. A composite of the doped compound with $$\hbox {BaTiO}_{3}$$ may find applications in the field of high-energy density capacitor. We believe that our results will be helpful in understanding the role of the electronic states of the dopants in superconductivity, especially in comparison with the monoclinic phase exhibited in the superconducting phase of $$\hbox {BaPb}_{0.75}\hbox {Bi}_{0.25}\hbox {O}_{3}$$ .

The polycrystalline powders of Pr1-xCaxCrO3 (x = 0, 0.02, 0.05) were prepared using solid state synthesis method. Lab source powder X-ray diffraction technique and Rietveld refinement are used for structural phase identification. The synthesized compounds are found to possess an orthorhombic structure with Pbnm space group. The substitution of Ca at Pr site does not affect the crystal structure but slight shrinkage in the lattice parameters and unit cell volume is observed. The optical properties are studied using diffuse reflectance spectroscopy technique. The energy band gap is observed to decrease from 3.20 eV (for PrCrO3) to 2.39 eV (for Pr0.95Ca0.05CrO3).

An improved electron field emission (FE) property from vertically aligned TiO2 nanorods (TNR) on conducting fluorine doped tin oxide coated glass substrate, prepared by hydrothermal technique, has been reported here. The TNRs having high aspect ratio with appropriate separation were prepared by optimizing the nucleation temperature. The TNR density has been optimized to cease the screening effect in closely packed nanorods. The well aligned rods have been designed so that the applied field is equally distributes on each rod to improve the electron emission. The morphology of the nanorod has been studied using scanning electron microscopy and observed FE current density-field response has been analysed within the frame work of Fowler-Nordheim modelling. Two orders of magnitude enhancement in the electric field has been observed for this kind of geometry giving improved turn on field and field enhancement factor of 0.2 V/μm and 37 thousands respectively.

A fast and flexible all-organic electrochromic device, fabricated using polythiophene and PCBM as active materials and plastic substrate, which shows very good power efficiency as well, has been re...

A precursor's concentration dependent surface morphologies of NiO nanopetals (NPs) have been studied for designing application-specific nanomaterials by hydrothermal technique. The surface morphologies, obtained using scanning electron microscopy, have been analysed using ImageJ to extract information about the dependence of petal thickness, petal density and linear porosity on the concentration at a given deposition and annealing temperatures. A detailed analysis shows how the synthesis parameters can be optimized to get a desired application specific nanostructure by taking an example of field emission properties. NiO NPs were prepared with three different precursor's concentrations out of which the sample prepared with lowest concentration was identified to show very good field emission property with high enhancement factor.

A bias-dependent in situ Raman scattering and UV–Vis absorption spectroscopic change has been correlated with the corresponding color change of an electrochromic device in an attempt to explain how to understand the relationship between actual perceived color and its absorption/transmittance spectra. For this, the bias across an electrochromic device was increased gradually, rather than abruptly turning ON and OFF, to see subtle variations in Raman and absorption spectra due to bias. Raman scattering establishes that viologen changes its oxidation state reversibly between two redox species (EV2+ to EV+•) as a result of bias-induced dynamic redox process. A gradual variation in Raman and absorption spectra, which shows maximum absorption corresponding to the yellow light, accompanies similar variation in color change of the device as visible by naked eye. These spectroscopic results are correlated with the perceived blue color, in the reflected light, by the eye to understand the actual reason behind this. Maximum absorption of yellow light by the device resulting in blue appearance has been explained using the concept of additive and subtractive primary colors.

An electrochromic device, capable of three-level color switching, has been envisaged by exploiting different color switching properties of Ethyl viologen (EV) and Poly (3-hexylthiophene) (P3HT) to make them switch in congruence with each other. The device, consisting of an EV/P3HT bilayer in poly-ethylene oxide matrix, appears magenta, blue or transparent under an appropriate bias. The unbiased device shows magenta colored appearance and turns transparent at a bias of 1 V when P3HT layer is used as anode. The device turns blue on increasing the bias to 1.4 V without changing the polarity. The mechanism of multilevel switching has been identified using UV–Vis and Raman spectroscopic investigations which reveal that the 1 V bias converts the P3HT into polarons and 1.4 V converts the EV dications (EV2+) into free radical. The electrochromic device demonstrates better color contrast (~ 50%) in both the optical domains. The fabricated device shows better switching speeds of ~ 1.5 s and good stability and coloration efficiency along with three-level color switching. However the reported device uses ITO coated glass as substrate, it can be used for all-organic flexible electrochromic device.

Optical properties of widely used semiconducting oxides namely; TiO2, ZnO and ZrO2 were investigated using diffuse reflectance spectroscopy (DRS). Prior to the optical absorption measurements, the structural purity of these samples was examined using powder x-ray diffraction experiments carried out on Indus-2 synchrotron source. It is observed that all the studied samples are structurally pure. The DRS of all the studied samples show an extra peak much below fundamental band gap. In order to understand the origin of the said low energy peak, the theoretical optical absorption spectra for these samples have been simulated. The simulations were performed using density functional theory, considering, ideal as well as defected systems i.e. by considering vacancy at all possible sites (for TiO2 we have considered the vacancy at Ti site and also at O site taking in to account surface and bulk effects). It is observed that the simulated optical spectra show very similar feature as that of experimental optical absorption for oxygen vacancy. Photoluminescence spectroscopy further supports the presence of defect states in the studied samples. Thus; it appears that the diffuse reflectance spectroscopy is a useful tool to probe the signature of defects present in the sample.

We report the structural and optical properties of ternary α-(GaxCr(1-x))2O3 with 0 ≤ x ≤ 0.45 which is synthesized by solid state reaction method. Single phase with space group R-3c is obtained for the gallium composition range of 0 ≤ x ≤ 0.45 and further increase in Ga concentration results in appearance of secondary C2/m phase corresponds to Ga2O3. Variations in the in-plane ’a’ and out of plane ’c’ lattice parameters shows a clear daviation from the Vegard's law with the bowing parameters of −0.0510 A and 0.0305 A respectively. Extended X-ray absorption fine structure (EXAFS) spectroscopy shows larger values of Ga-O bond lengths, which elucidate the deviation in lattice parameters from the Vegard's law and immisibility of Ga in Cr2O3 lattice. Diffuse reflectance spectroscopy (DRS) confirms a blue shift of 0.5 eV in the band gap of α-(GaxCr(1-x))2O3. It has also observed that Cr 3d level shifted towards the O 2p level in the valence band which has been reconfirmed by photo electron spectroscopy. The observed shift indicates enhancement of mixing between these levels which can leads to further delocalization of hole states in the valence band responsible for p-type conduction in the α-Cr2O3. These results suggest that ternary α-(GaxCr(1-x))2O3 (0 ≤ x ≤ 0.45) can be useful in the field of UV transperant electronics and photodetectors.

Rare-earth orthoferrites (RFeO3) are well-known for the antiferromagnetic ground state. However, some of the recent experimental results suggest that the few members of RFeO3 family possess ferromagnetism. In the present investigation we report the possible origin of ferromagnetism in antiferromagnetic YFeO3 using density functional theory. For this purpose, we have considered pure as well as self-doping in YFeO3 i.e. by considering the point defect at Y, Fe and O sites. Our finding suggests that the point defects in YFeO3 results in the mixed-valence state of Fe, which may result in ferromagnetism through Zener double exchange mechanism.

Fractal nature of porous silicon (Si), where porous nanowires (NWs) of Si has been observed inside the porous membrane matrix, has been revisited this time by metal assisted chemical etching (MACE) also known as metal induced etching or MIE. While carrying out MACE of Si wafer with silver nanoparticles (AgNPs) as the etching metal, it is observed that non vertical chemical etching take place. An SEM study reveals that the usual well aligned SiNWs, approximately 50 nm thick, consists of nanometer wide pores in themselves. The nanometer sized pores in turn results in Si NSs of a few nanometers in these thick looking SiNWs and are capable of showing quantum confinement effects. The SEM and TEM studies have been consolidated to model the growth mechanism for the observed fractal porous Si.

Improved electrochromism has been reported from a hybrid nanoheterostructure-based array designed using transition-metal oxides and conducting polymers. An improvement in color contrast, coloration efficiency, and operating voltage makes these hybrid core–shell-type nanostructures (NSs) suitable for power efficient and reversible electrochromic applications showing switching between transparent and opaque states rather than resulting in colored/bleached switching. Nanopetals (NPs) of nickel oxide have been used as the backbone to grow nanohemispheres (NHs) of polyaniline onto a fluorine-doped tin oxide electrode using a two-step synthesis methodology consisting of a hydrothermal method, followed by an electrodeposition method. The coaxial NPs/NHs core–shell arrays exhibit a better electrochromic performance compared to their individual constituents. Devices fabricated using these hybrid NSs show power efficient optical switching between transparent and opaque with fast response and a good cycle life of ap...

Quantification of the short-range order in amorphous silicon has been formulized using Raman scattering by taking into account established frameworks for studying the spectral line-shape and size dependent Raman peak shift. A theoretical line-shape function has been proposed for representing the observed Raman scattering spectrum from amorphous-Si-based on modified phonon confinement model framework. While analyzing modified phonon confinement model, the term "confinement size" used in the context of nanocrystalline Si was found analogous to the short-range order distance in a-Si thus enabling one to quantify the same using Raman scattering. Additionally, an empirical formula has been proposed using bond polarizability model for estimating the short-range order making one capable to quantify the distance of short-range order by looking at the Raman peak position alone. Both the proposals have been validated using three different data sets reported by three different research groups from a-Si samples prepared by three different methods making the analysis universal.

Detailed structural analysis of rare-earth orthoferrites RFeO3 (R = La, Pr, Nd, Sm, Eu, Tb, Dy, Y, Ho, Er, and Yb) has been reported. Polycrystalline samples of RFeO3 were prepared using the sol-ge...

Effect of R site ionic radius on the structural, optical and electronic properties of rare-earth orthoferrites (RFeO 3 ) (where, R = La, Pr, Nd, Sm, Eu, Tb, Dy, Y, Ho, Er, and Yb) have been investigated experimentally and theoretically. Synchrotron-based X-ray diffraction studies followed by Rietveld refinement confirmed that the lattice constants, R–O bond length and Fe–O–Fe bond angle increase systematically, whereas the Fe–O bond length (i.e. overlap between O-2p and Fe-3d orbitals) associated with FeO 6 octahedra almost remains constant throughout RFeO 3 series. The energy bandgap (E g ) of all the samples have been measured using optical absorption spectroscopy and the same is found between ~ 1.94 and 1.97 eV, i.e. E g almost remains constant throughout RFeO 3 series. First principle DFT analysis confirmed that the “density of states” near Fermi level in all the studied samples is dominated by O-2p and Fe-3d orbitals. Thus, it appears that the constant value of Fe–O bond length (i.e. Fe-O overlap) associated with FeO 6 octahedra might be responsible for the constant value of band gap in these samples.

Nano-metal/semiconductor junction dependent porosification of silicon has been studied here. The silicon nanostructures (SiNSs) have been textured on n- and p- type silicon wafers using Ag (silver) and Au (gold) metal nano particles induced chemical etching. The combinations of n-silicon/Ag as well as p-silicon/Au form ohmic contact and result in the same texturization on the silicon surface on porosification, where tent-shaped morphology has been observed consistently in both n- and p-type silicon. Whereas, porosification result in different surface texturization for other two combinations (p-silicon/Ag and n-silicon/Au) where Schottky contacts are formed. Quantitative analysis have been done using ImageJ to process the scanning electron microscopy images of silicon NS, which confirms that the tent like silicon NS are formed when Ohmic junction is built. These easily prepared sharp tent-shaped Si NSs can be used for enhanced field emission applications.

In the present study, we designed and fabricated a cost-effective miniaturized versatile electrochemical deposition cell, which is found to be at par performance as compared with conventional electrodeposition techniques. A case study is being undertaken for the electrodeposition of varied thicknesses of bismuth ferrite (BiFeO3) films on FTO glass substrates. X-ray diffraction (XRD) patterns confirm the structural perovskite phase of BiFeO3 (BFO). UV–visible absorption spectra and Tauc plot of BFO estimate the direct band gap which lies between 1.9 to 2.1 eV. The properties of the bismuth ferrite crystal system such as electronic band structure and density of states (DOS) are investigated theoretically. Photoelectrochemical (PEC) water splitting application is carried out to investigate the best performance of BFO films of varied thicknesses. The best performer (BFO15) working electrode yields a photocurrent density of ∼35 μA cm−2 at 0.2 V vs RHE under visible LED (light intensity of 100 mW cm−2) in neutral 0.5 M Na2SO4 electrolyte. Incident photon to current conversion (IPCE) measurements, electrochemical impedance spectroscopy (EIS), and Mott-Schottky characteristics confirm the best performance of BFO15 photocathode film.

A suitably designed heterostructured TiO2–Co3O4 core–shell nanorod array has been found to exhibit improved supercapacitive as well as electrochromic properties as compared to the nanowires of either of the oxides when used individually. The core–shell nanostructures have been grown on an FTO coated glass substrate by preparing TiO2 nanorods through hydrothermal reaction followed by growing a Co3O4 shell layer by electrodeposition. The core–shell electrode shows high specific and areal capacitance of ∼342 F/g and ∼140 mF/cm2 (at scan rate of 100 mV/s), respectively. Such an improvement in supercapacitive behavior, as compared to the behavior of the existing ones, is likely due to increased surface area and modified charge dynamics within the core–shell heterojunction. Additionally, these core–shells also exhibit stable and power efficient bias induced color change between transparent (sky blue) and opaque (dark brown) states with coloration efficiency of ∼91 cm2/C. Porous morphology and strong adhesion to...

In the present work, the interaction of phosphorous heterocycle (PH) with calf thymus DNA (CTDNA) has been studied using spectroscopy and verified by molecular modeling which is found to be in consonance with each other. Apparent association constant (Kapp = 4.77 × 103 M− 1), calculated using UV–Vis spectra indicating an adequate complex formation between CTDNA and PH. A dynamic mode of the fluorescence quenching mechanism in case of ethidium bromide (EB) + CTDNA by PH has been observed confirming formation of DNA-PH complex. A moderate binding constants of PH with CTDNA + EB has been observed (2.74 × 104 M− 1 at 293 K) by means of fluorescence data. Calculated values of thermodynamic parameters enthalpy change (ΔH) and entropy change (ΔS), suggests weak (van der Walls like) force and hydrogen bonds playing the main role in the binding of PH to CTDNA. Furthermore, the results of circular dichroism (CD) reveal that PH does not disturb native conformation of CTDNA. As observed from absorption and fluorescence spectroscopy the binding mode of PH with DNA was indicative of a non-intercalative binding, which was supposed to be a groove binding. The molecular modeling results show that PH is capable of binding DNA having docking binding energy = -7.26 kcal × mol− 1. Above mentioned experimental results are found to be in consonance with molecular docking simulations and supports the CTDNA-PH binding.

Optical and electronic properties of hybrid Polypyrrole (Ppy)–Titanium oxide (TiO2) nanocomposite, synthesized using oxidative chemical polymerization method have been investigated here. The synthesized organic–inorganic hybrid materials have been characterized using XRD, FT-IR, FESEM, UV–Vis, Raman, and TGA. Electrical conductance and dielectric behavior of the electrical phenomena of the sample have also been investigated. XRD results demonstrate the amorphous nature of Ppy, however, its composites with TiO2 exhibit crystalline nature. FT-IR spectroscopy reveals the presence of interaction between conducting Ppy and TiO2. UV–Vis study show changes in spectra of Ppy in presence of TiO2 with a slight increase in the band gap. The SEM results reveal encapsulation of TiO2 particles in Ppy matrix and agglomeration of grains have also been observed with evident changes in morphology with increasing percentages of TiO2. TGA data indicates that the composite materials show good thermal stability. Conductance results show that electrical conductivity of Ppy increases upon addition of TiO2. It has also been noticed that the dielectric parameters (dielectric constant, loss tangent) of Ppy vary with addition of TiO2. The resulting insight clearly suggests that by embedding TiO2 in Ppy the electrical properties of the composites can be improved.

In-situ Raman and UV–vis spectroscopies have been carried out from viologen based electrochromic device fabricated in two simple geometries. Ethyl viologen diperchlorate in polyethylene oxide matrix was used as the active layer in the device without any counter material to understand the effect of bias on viologen. The device, which is transparent otherwise, changes its color to navy blue when a bias of 2 V is applied. Reduction of viologen to its free radical state as revealed from Raman spectroscopy recorded in-situ in both the geometries appears to be the mechanism for this color switching. It is also observed that absorbance of the device is perturbed when bias is applied with maximum change in absorbance corresponding to green wavelength which is giving the blue tint of the device in on state. We establish that UV–vis and Raman spectroscopies prove to be the best method for understanding the mechanism of color switching in viologen based electrochromic device because it gives the advantage to see a device ‘live’ while operating.

One step morphology transformation has been reported here by the addition of ammonium fluoride. Two different morphologies of the same structure have been reported for Cobalt Oxide nanostructures. ...

In order to realize the effect of Mn doping on dielectric behavior and optical band gap (Eg) of Lanthanum Gallate; pure and Mn doped LaGaO3 samples were prepared. The phase purity of these samples ...

The binding ability of viologen herbicide with bovine serum albumin (BSA) has been investigated to understand viologen associated hazards by investigating ethyl viologen's (EV) binding using various spectroscopies and in-silico molecular docking approaches. Apparent association constant (1.3 × 10 4 L/mol), calculated using UV–Vis spectra indicating a moderate complex formation between BSA and EV. A static mode of fluorescence quenching has been observed as evident from inverse temperature dependence of Stern-Volmer quenching constant which also confirms an EV–BSA complex formation. Emission and time resolved fluorescence studies reveal that the emission quenching of BSA with EV is initiated by static quenching mechanism. A moderately strong binding affinity between EV and BSA has been observed (binding constant value of 7.58 × 10 4 L/Mol) using fluorescence quenching titration, obtained at 298 K. Quantitative measurements of thermodynamic parameters like enthalpy and entropy changes clearly indicates hydrophobic force responsible for EV–BSA complex formation. The binding distance between EV and BSA was found to be 4.48 nm are involved in non-radiative energy transfer process. Furthermore, from the circular dichroism spectra it was observed that addition of EV is also found to change the secondary structure of BSA which leads to decrease in α-helix. Above mentioned results are found to be in consonance with molecular docking simulations and supports the EV–BSA binding.

In an attempt to understand the color switching mechanism of organic electrochromic devices, live spectroscopy of a viologen based device has been done. Role of redox reactions taking place at the electrode/electrolyte interface has been identified using Raman and UV–Vis spectroscopies carried out during the device operation. In-situ Raman and transmission/absorption studies establish the origin of bias induced color change, between a transparent and navy blue color, in the electrochromic device. The origin of color change has been attributed to the bias induced redox switching between its dication and free radical forms which have different optical properties from each other. Raman spectra collected from negative and positive electrodes of the device reveal that blue color species (free radical) are present at the negative electrode which is created due to reduction of the dicationic form. In-situ UV–Vis spectra reveals that the navy blue color of the device under biased condition is not due to increase in the transparency corresponding to the blue wavelength but due to suppression of its transparency corresponding to the complementary colors as studied using a from CIE (Commission Internationale de l’Eclairge International Commission on Illumination) chart. Absorption modulation has been reported from the device with good ON/OFF contrast of the device.