Optical UV Research Articles

Antifungal action and targeted mechanism of Bio fabricated zinc oxide (ZnO) nanoparticles against Ascochytafabae

The current work focuses on analysing the structural, optical, and anti-fungal efficacy of ZnO nanoparticles using well diffusion agar methods and minimum inhibitory concentration (MIC). ZnO nanoparticles were created using the sol gel method. To check the synthesized material's spatial and optical characteristics, XRD, UV, and RAMAN studies were performed. The median diameter of produced nanostructures is in the region of nanometre, according to XRD measurements. Results from Raman Spectroscopy for the nanostructure are provided, together with comparisons to current development theory and reliable experimental data. The band gap of the zinc oxide sample is found by graphing (h) 2versus input photon energy and gradually decreasing the linear component of the (h) 2 to zero. The band gap energy is expressed by the line's intersection with the energy axis. Calculations show that the energy band gap is 3.22eV.The fungus Ascochytafabae is in control of the Phaseolus vulgaris L. (beans) blight disease. It mostly affects the plant's stem, leaves, and fruits. Phaseolus vulgaris plant leaf with Ascochytafabae infection was isolated, and ZnO nanoparticle effects were observed. It emerged that the synthesized ZnO nanoparticles were highly efficient against Ascochytafabae. By using the well diffusion method and an absolute concentration of ZnO nanoparticles, the maximum inhibitory concentration was 15.0 ± 0.2 mm.

Sustainable route to prepare functional lignin-containing cellulose nanofibrils

With nano-dimension, high aspect ratio, and high mechanical properties, cellulose nanofibrils (CNFs) are emerging sustainable nanomaterials with potential applications in films and composites. However, their preparation often involves a series of chemical treatments such as delignification, bleaching and harsh chemical pretreatments, and treats lignin as waste. Herein, we report a sustainable method to prepare high-quality lignin-containing cellulose nanofibrils (LCNFs) from bamboo chips, using a one-step maleic anhydride esterification treatment without any toxic organic solvent or catalyst. The resultant LCNFs have high lignin content (24%), high surface charge (2.25 mmol/g), fine diameter (∼2.5 nm), and high aspect ratio (>400). These superior properties can be translated into the corresponding nanopaper films with high optical transmittance (85% at 600 nm), UV shielding (<10% transmittance at 200–350 nm), hydrophobicity (water contact angle 75°), thermal stability (maximal weight loss temperature at 338 °C), and mechanical properties. Importantly, such films show the best reported tensile strength (290 MPa) among all the LCNF films, and it still outperforms conventional CNF films after 5 rounds of recycling. Furthermore, as sustainable nanofillers, such LCNFs can be directly incorporated into a hydrophobic polyester matrix, and significantly enhances the UV shielding and mechanical properties of the final nanocomposites. Altogether, with eco-friendly production and multiple functions, these LCNFs are a new class of nanocelluloses with high industrial relevance.

The Early Light Curve of SN 2023bee: Constraining Type Ia Supernova Progenitors the Apian Way

We present very early photometric and spectroscopic observations of the Type Ia supernova (SN Ia) 2023bee, starting about 8 hr after the explosion, which reveal a strong excess in the optical and nearest UV (U and UVW1) bands during the first several days of explosion. This data set allows us to probe the nature of the binary companion of the exploding white dwarf and the conditions leading to its ignition. We find a good match to the Kasen model in which a main-sequence companion star stings the ejecta with a shock as they buzz past. Models of double detonations, shells of radioactive nickel near the surface, interaction with circumstellar material, and pulsational delayed detonations do not provide good matches to our light curves. We also observe signatures of unburned material, in the form of carbon absorption, in our earliest spectra. Our radio nondetections place a limit on the mass-loss rate from the putative companion that rules out a red giant but allows a main-sequence star. We discuss our results in the context of other similar SNe Ia in the literature.

Investigation on the synthesis, growth, thermal and optical behavior of creatininium borate single crystal: A potential candidate for nonlinear optical applications

In the this study, we focus on the growth of a metal-organic creatininium borate (CRB) single crystal for third-order nonlinear optical (NLO) applications. Optically transparent &amp; wide optical band gap single crystals of CRB were successfully harvested by adopting a slow evaporation solution technique (SEST) at a constant 40[Formula: see text]C temperature. The structural identification and lattice parameters of the grown sample were determined by powder X-ray diffraction (PXRD) using Rietveld analysis by FullProf Suite software. The occurrence of vacancy/interstitial defects produced during growth was investigated by high-resolution X-ray diffraction (HRXRD) using omega scan arrangement. A single peak with lower full width half maxima (56.4 arc s) was obtained from the scan which suggests that there were no grain boundaries for the grown crystal. Surface morphology and its features such as concentration of dislocations and defect sites on the as-grown sample were scrutinized using the etching technique. The optical band gap and UV–vis cut-off were examined and found to be 5.39 eV and 230 nm, respectively. Photoluminescence characteristics of the crystal show an emission at 377 nm upon excitation with a wavelength of 336 nm. The presence of radiative and non-radiative transitions inside the crystal due to excitation upon 266 nm laser was identified using time-resolved photoluminescence. Thermal stability and decomposition temperature of the compound were obtained by thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The third-order nonlinearity of the crystal was determined by Z-scan measurement technique with a femtosecond Ti-sapphire laser.

Molecular scale insights from NMR studies of hybrid systems formed via doping silver QDs in 6CHBT liquid crystal: a quantitative investigation of their optoelectronic properties

ABSTRACT We have successfully synthesised silver quantum dots (Ag QDs) via chemical method. We have studied Ag QDs doped 4-(trans-4-n hexylcyclohexyl) isothiocyanatobenzoate (6CHBT) LC hybrid system and their associated structural and optoelectronic properties using both experimental and theoretical methods. The QDs with sizes 4.27 nm−9.56 nm self-assemble to form nano-micro scale hierarchical structures. Theoretical NMR study has been performed using three different methods HF, B3LYP, and wB97XD for pure and Ag NPs doped LC system. NMR data greatly helps us to explore the phenomenological description of the hybrid system by giving us molecular scale insights. Optical microscope, RAMAN, UV, FTIR, HR-XRD, FESEM-EDX, and Fluorescence data confirm the structural and physio-chemical properties of QDs, LC molecules and as well as their hybrid system. We use a nanoscale predictive model to estimate the effective size to which the bandgap value of Ag QDs in a hybrid system corresponds. The bandgap value of pure Ag QDs is found to be 5.32 eV, whereas upon doping these Ag QDs in LC media, their bandgap falls to a value of 4.08 eV. The estimated size (i.e. corresponding to effective confinement) using a hexahedral or octahedral-shaped particle model comes out to be ~15 nm.

PENELLOPE

Context. Observing the spatial distribution and excitation processes of atomic and molecular gas in the inner regions (&lt;20 au) of young (&lt;10 Myr) protoplanetary disks helps us to understand the conditions for the formation and evolution of planetary systems. Aims. In the framework of the PENELLOPE and ULLYSES projects, we aim to characterize the atomic and molecular component of protoplanetary disks in a sample of 11 classical T Tauri stars of the Orion OB1 and σ-Orionis associations. Methods. We analyzed the flux-calibrated optical forbidden lines and the fluorescent ultraviolet H2 progressions using spectra acquired with ESPRESSO at VLT, UVES at VLT, and HST-COS. Line morphologies were characterized through Gaussian decomposition. We then focused on the properties of the narrow low-velocity (full width half maximum &lt;40 km s−1 and |υp| &lt; 30 km s−1) component (NLVC) of the [O I] 630 nm line and compared them with those of the UV-H2 lines. Results. We found that the [O I]630 NLVC and the UV-H2 lines are strongly correlated in terms of peak velocities, full width at half maximum values, and luminosity. Assuming that the line width is dominated by Keplerian broadening, the [O I]630 NLVC originates from a disk region between 0.5 and 3.5 au, while that of UV-H2 originates in a region from 0.05 to 1 au. The luminosities of [O I]630 NLVC and UV-H2 correlate with an accretion luminosity with a similar slope, as well as with the luminosity of the C IV154.8, 155 nm doublet. We discuss such correlations in the framework of the currently suggested excitation processes for the [O I]630 NLVC. Conclusions. Our results can be interpreted in a scenario in which the [O I]630 NLVC and UV-H2 have a common disk origin with a partially overlapped radial extension. We also suggest that the excitation of the [O I] NLVC is mainly induced by stellar far-ultraviolet continuum photons, than being of mostly thermal origin. This study demonstrates the potential of contemporaneous wide-band highresolution spectroscopy in linking different tracers of protoplanetary disks.

Chemical Synthesis by Precipitation of Zinc Oxide for Boimedical Application

Abstract The objective of the study is the chemical synthesis of ZnO powders, from ZnCl2 and NaOH solutions according to an appropriate procedure. The powders (a) and (b) obtained underwent various characterizations such as: optical microscopy, SEM, UV, BET, IR, XRD and antimicrobial activity. The results showed the inhomogeneous distribution, the nanometric size, the absorbance at 353 and 346 nm and the specific surface of 25.701 and 30.534 cm2/g of the particles, the presence of all the characteristic bands of ZnO which was confirmed by XRD and very good bacterial sensitivity of the two ZnO powders.

Microwave-Assisted Synthesis of New 4-Amino Acid Substituted 1,2,4-Triazole Derivative Derived from 1,2,3-Oxadiazole Nucleus and Their Anti-Bacterial and Anti-Oxidant Potential

Heterocyclic compounds especially, five or six-member heterocyclic compounds, having one to three hetero-atoms in their nucleus take part in metabolism of all living cells. And this information gives the lead for synthesizing heterocyclic derivatives. This research work has focused on development of new method for synthesis of some new amino acid substituted 1,2,4-trizole derivative from 1, 3, 4-Oxadizole nucleus. The nucleus of the 1, 3, 4-Oxadizole was first produced by reaction of Isoniazide and 3-chlorobenzeldehyde which is then converted into 1,2,4-trizole derivative by the loss of water molecule. After that incorporation of different amino acid (luecine and glycin) leads new amino acid substituted 1,2,4-trizole derivative. The newly synthesized derivative Compound A1 and A2 were characterized by optical rotation, melting point, TLC, UV spectroscopy and IR. The antibacterial was screened using Disc diffusion method with ciprofloxacin as reference drug and antioxidant activity by in-vitro DPPH method using ascorbic acid as standard drug. Synthesized compound A1 showed maximum MIC against S. aureus as compared to Compound A2. For antioxidant activity, compound A1 showed maximum percentage inhibition as compared to Compound A2.

Study of the Sensitivity Limit of Detection of α-Particles by Polymer Film Detectors LR-115 Type 2 Using X-ray Diffraction and UV-Vis Spectroscopic Methods.

This work is devoted to the applicability assessment of optical spectroscopy and X-ray diffraction methods to establish the lower detection limit for the density of latent tracks from α-particles in polymer nuclear-track detectors, in the case of simulation of the formation of radon decay daughter products using Am-241 sources. During the studies, the detection limit for the density of latent tracks-traces of the interaction of α-particles with the molecular structure of film detectors-was established using optical UV spectroscopy (104 track/cm2) and X-ray diffraction (104 track/cm2). At the same time, analysis of the connection between structural and optical changes in polymer films indicates that a growth in the density of latent tracks above 106-107 results into the formation of an anisotropic change in the electron density associated with distortions in the molecular structure of the polymer. An analysis of the parameters of diffraction reflections (the position and width of the diffraction maximum) showed that in the range of latent track densities of 104-108 track/cm2, the main changes in these values are associated with deformation distortions and stresses caused by ionization processes during the interaction of incident particles with the molecular structure of the polymer. The increase in optical density, in turn, is caused by the accumulation of structurally changed regions (latent tracks) in the polymer as the irradiation density increases. A general analysis of the obtained data showed good agreement between the optical and structural characteristics of the films depending on the irradiation density.

Effect of neodymium (Nd) doping on the photocatalytic organic dye degradation performance of sol-gel synthesized CoFe2O4 self-assembled microstructures

Trivalent Neodymium doped CoFe2O4 was investigated as the potent photocatalyst for wastewater treatment. The CoFe2O4 and Nd-doped CoFe2O4 with various concentrations, such as 5, 10, and 15%, were prepared to employ the sol-gel technique. Structural characterization of the synthesized materials was done by powder X-ray Diffraction and Raman studies. The optical UV–Visible spectroscopy provides the optical properties of CoFe2O4 and Nd-doped CoFe2O4 and the XPS spectra, which identify the constituting elements with their oxidation states, confirm the incorporation of Nd into the CoFe2O4 lattice. SEM was performed to investigate their surface morphology, showing the self-assembled microstructures of CoFe2O4. The dye degradation process was investigated for the synthesized samples with methylene blue dye using UV–Visible spectroscopy, which reveals the photocatalytic performance of pure CoFe2O4 and Nd doped CoFe2O4 by measuring the absorbance of methylene blue at the same interval of time. The 5% Nd doped CoFe2O4 exhibits enhanced photocatalytic activity with a degradation efficiency of 72% within 4 h, which is higher than the pure sample. Outcomes indicates that the synthesized material can be useful in wastewater treatment.

Ba3GeTeS4: A new quaternary heteroanionic chalcogenide semiconductor

We report the synthesis and characterization of a new quaternary heteroanionic chalcogenide phase, Ba3GeTeS4. A single-crystal X-ray diffraction study of a yellow-colored crystal of Ba3GeTeS4 shows that the compound is stoichiometric and crystallizes in the orthorhombic Cmcm space group having cell parameters of a ​= ​6.8583(12) Å, b ​= ​16.207(3) Å, c ​= ​9.6239(19) Å, with four formula units (Z ​= ​4) per unit cell. The unit cell of the structure consists of two Ba, one Ge, one Te, and two S sites. All the crystallographically independent atoms occupy special positions. The Ba3GeTeS4 structure is made up of zero-dimensional [GeS4]4– anionic units along with Ba2+ cations, each of that is surrounded by the Te and S atoms. An optical UV–Vis absorption study on a polycrystalline sample of Ba3GeTeS4 establishes its semiconducting nature with a direct bandgap of 2.5(2) eV consistent with the yellow color of the sample. The polycrystalline Ba3GeTeS4 shows an extremely low value of thermal conductivity (∼0.46 W/mK) at 723 ​K. The ab-initio DFT calculations predict a high value of the thermoelectric figure of merit (zT ​> ​1) for the hole doped-Ba3GeTeS4 sample. The crystal orbital Hamilton population (COHP) analysis shows that the Ge–S bonds are strongest in the structure, while the strengths of the Ba–S and Ba–Te interactions are similar.

Discovery of the luminous X-ray ignition eRASSt J234402.9−352640

In November 2020, a new, bright object, eRASSt J234402.9−352640, was discovered in the second all-sky survey of SRG/eROSITA. The object brightened by a factor of at least 150 in 0.2–2.0 keV flux compared to an upper limit found six months previous, reaching an observed peak of 1.76−0.24+0.03 × 10−11 erg cm−2 s−1. The X-ray ignition is associated with a galaxy at z = 0.10, making the peak luminosity log10(L0.2−2 keV/[erg s−1]) = 44.7 ± 0.1. Around the time of the rise in X-ray flux, the nucleus of the galaxy brightened by approximately 3 mag. in optical photometry, after correcting for the host contribution. We present X-ray follow-up data from Swift, XMM-Newton, and NICER, which reveal a very soft spectrum as well as strong 0.2–2.0 keV flux variability on multiple timescales. Optical spectra taken in the weeks after the ignition event show a blue continuum with broad, asymmetric Balmer emission lines, and high-ionisation ([OIII]λλ4959,5007) and low-ionisation ([NII]λ6585, [SII]λλ6716,6731) narrow emission lines. Following the peak in the optical light curve, the X-ray, UV, and optical photometry all show a rapid decline. The X-ray light curve shows a decrease in luminosity of ∼0.45 over 33 days and the UV shows a drop of ∼0.35 over the same period. eRASSt J234402.9−352640 also shows a brightening in the mid-infrared, likely powered by a dust echo of the luminous ignition. We find no evidence in Fermi-LAT γ-ray data for jet-like emission. The event displays characteristics of a tidal disruption event (TDE) as well as of an active galactic nucleus (AGN), complicating the classification of this transient. Based on the softness of the X-ray spectrum, the presence of high-ionisation optical emission lines, and the likely infrared echo, we find that a TDE within a turned-off AGN best matches our observations.

Absence of the predicted 2022 October outburst of OJ 287 and implications for binary SMBH scenarios

ABSTRACT The project MOMO (Multiwavelength Observations and Modelling of OJ 287) was set up to test predictions of binary supermassive black hole (SMBH) scenarios and to understand disc–jet physics of the blazar OJ 287. After a correction, the precessing binary (PB) SMBH model predicted the next main outburst of OJ 287 in 2022 October, making the outburst well observable and the model testable. We have densely covered this period in our ongoing multifrequency radio, optical, ultraviolet (UV), and X-ray monitoring. The predicted outburst was not detected. Instead, OJ 287 was at low optical–UV emission levels, declining further into November. The predicted thermal bremsstrahlung spectrum was not observed either, at any epoch. Further, applying scaling relations, we estimate an SMBH mass of OJ 287 of 108 M⊙. The latest in a sequence of deep low states that recur every 1–2 yr is used to determine an upper limit on the Eddington ratio and on the accretion-disc luminosity. This limit is at least a factor of 10 lower than required by the PB model with its massive primary SMBH of &amp;gt;1010 M⊙. All these results favour alternative binary SMBH models of OJ 287 that require neither strong orbital precession nor a very large mass of the primary SMBH.

MOMO. VI. Multifrequency Radio Variability of the Blazar OJ 287 from 2015 to 2022, Absence of Predicted 2021 Precursor-flare Activity, and a New Binary Interpretation of the 2016/2017 Outburst

Based on our dedicated Swift monitoring program, MOMO, OJ 287 is one of the best-monitored blazars in the X-ray–UV–optical regime. Here, we report results from our accompanying, dense, multifrequency (1.4–44 GHz) radio monitoring of OJ 287 between 2015 and 2022 covering a broad range of activity states. Fermi γ-ray observations were added. We characterize the radio flux and spectral variability in detail, including discrete correlation function and other variability analyses, and discuss its connection with the multiwavelength emission. Deep fades of the radio and optical–UV fluxes are found to occur every 1–2 yr. Further, it is shown that a precursor flare of thermal bremsstrahlung predicted by one of the binary supermassive black hole (SMBH) models of OJ 287 was absent. We then focus on the nature of the extraordinary, nonthermal, 2016/2017 outburst that we initially discovered with Swift. We interpret it as the latest of the famous optical double-peaked outbursts of OJ 287, favoring binary scenarios that do not require a highly precessing secondary SMBH.

Multiwavelength astrophysics of the blazar OJ 287 and the project MOMO

AbstractWe are carrying out the densest and longest multiyear, multiwavelength monitoring project of OJ 287 ever done. The project MOMO (Multiwavelength Observations and Modeling of OJ 287) covers wavelengths from the radio to the high‐energy regime. A few selected observations are simultaneous with those of the Event Horizon Telescope (EHT). MOMO aims at understanding disk‐jet physics and at testing predictions of the binary black hole scenario of OJ 287. Here, we present a discussion of extreme outburst and minima states in context, and then focus on the recent flux and spectral evolution between 2021 and May 2022, including an ongoing bright radio flare. Further, we show that there is no evidence for precursor flare activity in our optical–UV–X‐ray light curves that would be associated with any secondary supermassive black hole (SMBH) disk impact and that was predicted to start as thermal flare on December 23, 2021.

Improvement in ammonia gas sensing properties of Co doped MoO3 thin films prepared by cost effective nebulizer spray pyrolysis method

The capacity to detect and monitor NH3 in the environment in real time has been established using an ammonia (NH3) sensing material consisting of Cobalt (Co) doped Molybdenum trioxide (MoO3) thin films on glass substrates. With Co doping, the XRD peaks of MoO3 films shifted towards lower angle and increase cell volume in the case of 3% Co doped MoO3 film compared to other samples, depicts the successful Co doping into the host structure. The chain link particles observed for as-fabricated MoO3film increased for Co doped films and obtained maximum particle size for 3% Co doped MoO3 film. In addition, to test the films elemental and optical properties, energy-dispersive X-ray (EDX) and UV spectroscopy were used to analyze the prepared samples. Simultaneously, we established the gas-sensing characteristics of Co-doped MoO3 sensors for NH3 detection at room temperature and attained maximum gas response of 9120 % for 3% Co doped MoO3 film. The sensor with 3%Co doped MoO3 sensing film exhibited faster response and recovery times than sensor with undoped MoO3 film, which is critical for MoO3 sensor practical applications. Furthermore, the ammonia selectivity of the doped MoO3 sensors was found to be remarkable.

Facile Fabrication of Flexible Polymeric Membranes with Micro and Nano Apertures over Large Areas.

Freestanding, flexible and open through-hole polymeric micro- and nanostructured membranes were successfully fabricated over large areas (>16 cm2) via solvent removal of sacrificial scaffolds filled with polymer resin by spontaneous capillary flow. Most of the polymeric membranes were obtained through a rapid UV curing processes via cationic or free radical UV polymerisation. Free standing microstructured membranes were fabricated across a range of curable polymer materials, including: EBECRYL3708 (radical UV polymerisation), CUVR1534 (cationic UV polymerisation) UV lacquer, fluorinated perfluoropolyether urethane methacrylate UV resin (MD700), optical adhesive UV resin with high refractive index (NOA84) and medical adhesive UV resin (1161-M). The present method was also extended to make a thermal set polydimethylsiloxane (PDMS) membranes. The pore sizes for the as-fabricated membranes ranged from 100 µm down to 200 nm and membrane thickness could be varied from 100 µm down to 10 µm. Aspect ratios as high as 16.7 were achieved for the 100 µm thick membranes for pore diameters of approximately 6 µm. Wide-area and uniform, open through-hole 30 µm thick membranes with 15 µm pore size were fabricated over 44 × 44 mm2 areas. As an application example, arrays of Au nanodots and Pd nanodots, as small as 130 nm, were deposited on Si substrates using a nanoaperture polymer through-hole membrane as a stencil.

Optical and surface properties of Gd-doped ZnO thin films deposited by thermionic vacuum arc deposition technology

In this paper, Zinc oxide (ZnO) was doped with Gadolinium (Gd) and it was deposited onto the glass and silicon substrates by thermionic vacuum arc (TVA) method to examine its morphological, compositional, and optical properties. The results show that the substrates strongly affect the morphological structures of the thin films. According to the obtained information, the surface roughness was found to be 38 nm and 6 nm for silicon and glass respectively. The images showed that the surface onto the glass had more symmetry and more regular grains. The optical properties of the nano composite on the glass substrate were analyzed with an optical interferometer and UV–Vis spectrophotometer. Absorbance, transparency, and refractive index of the thin film were obtained. It also had a relatively high refractive index. Furthermore, it was found that the band gap of ZnO decreased. The band gap of the deposited thin film was found 3.3 eV.

STUDY OF THE EFFECT OF ZCO CERAMIC PHASE COMPOSITION ON OPTICAL AND THERMOPHYSICAL PROPERTIES

The work is devoted to the study of optical and thermophysical properties of promising materials for nuclear power of a new generation - inert matrices of nuclear dispersed fuel based on ZrO2 – CeO2 (ZCO) doped with Y2O3. Interest in this class of materials is due to great prospects in the field of replacing the traditional type of nuclear fuel with uranium-free dispersed nuclear fuel, which is based on a technological solution using plutonium as a fissile element, placed in a dispersed inert matrix based on oxide or nitride ceramics. The purpose of this work is to study the effect of doping of ZCO ceramics with Y2O3 on the optical and heat-conducting properties. During the study, it was found that an increase in the concentration of the Y2O3 dopant leads to the formation of a highly ordered CeZrO4 phase, the presence of which leads to the appearance of an additional absorption band in the region of 550 – 650 nm, as well as a decrease in the transmission value in the region of 400 – 700 nm. To evaluate the results obtained, the methods of optical UV spectroscopy and heat flux determination were applied. It has been found that doping with Y2O3 leads to the formation of a highly ordered CeZrO4 phase, the formation of which leads to the appearance of additional spectral absorption lines, as well as a shift in the band gap to the region of low energies. During analysis of the thermophysical parameters, it was found that a change in the phase composition leads to an increase in the thermal conductivity coefficient by more than 40 – 60 %.

Polysulfide Speciation in Li–S Battery Electrolyte via In-Operando Optical Imaging and Ex-Situ UV-vis Spectra Analysis

Lithium sulfur (Li–S) batteries have received significant attention as one of the energy storage systems with excellent prospects for emerging applications due to their high energy density and low-cost. However, there are fundamental challenges impeding the commercialization of Li–S batteries. Notorious among those challenges is the “polysulfide shuttle” consisting of the dissolution into the electrolyte solvent and subsequent crossover to the anode of long-chain lithium polysulfides. Sparingly solvating electrolytes have been exploited as an approach to reduce the dissolution of polysulfides and thereby the shuttle effect. Using an optical in operando lithium-sulfur cell and ex situ UV–vis spectroscopy, we elucidate the speciation of polysulfides in fully and sparingly solvating electrolytes for Li–S batteries. Extensive literature meta-analysis reveals that the most unambiguous effect of sparingly solvating solvent is in improving the coulombic efficiency of sulfur-cells. Experimental optical imaging and UV–vis characterization elucidate a shift towards shorter-chain polysulfides in electrolytes with increasing lithium-salt concentration (more sparingly solvating). The shift to shorter-chain polysulfides corresponds to a reduction of polysulfide species participating in shuttling which corroborate the increased coulombic efficiency in sparingly-solvating electrolytes.