Spectra Of CO Research Articles

Influence of transition metals dopant type on the structural, optical, magnetic, and dielectric properties of ZnS nanoparticles prepared by ultrasonication process

Undoped and (Ni, Co, and Mn)-doped ZnS nanoparticles (NPs) are successfully synthesized by a sonochemical-assisted co-precipitation technique. XRD patterns reveals the incorporation of dopant ions by substitution of Zn ions. Ni ions induce growth rate enhancement and the increase of crystallite size, whereas Co and Mn ions slow down the growth rate and caused the decrease of the corresponding crystallite size. The UV–visible absorption spectra exhibit a decrease in the optical band gap for all doped samples. The photoluminescence spectra of Co- and Mn-doped ZnS NPs show an improvement in the visible-light, whereas Ni-doping results in a slight decrease in the emission intensity allover spectral range. The room-temperature ferromagnetism of ZnS NPs is strongly improved by Ni- and Co-doping and slightly enhanced by Mn-doping. The AC conductivity of ZnS NPS is enhanced by Ni- and Co-doping and decreased by Mn-doping in the frequency range from 2 kHz to 1 MHz.

An IRTF-iSHELL Survey of 4.52–5.25 μm CO Spectra in Protoplanetary Disks of Intermediate-mass Stars: Preliminary Sample and Analysis

Abstract We are conducting a survey of high-resolution near-infrared CO rovibrational spectra in protoplanetary disks around young intermediate-mass stars. We use IRTF-iSHELL with the 0.″375 and 0.″75 slits, providing 4 km s−1 and 6 km s−1 resolution and covering 4.52–5.25 μm in one single exposure. This includes part of the rovibrational R branch and most of the P branch of the CO fundamental band (Δv = 1), one of the best tracers of warm/hot gas in disks. The high quality of the spectra and the large sample covered in this survey will support multiple investigations to study the structure, kinematics, composition, and evolution of the inner 10 au in disks for years to come. The survey currently includes ∼30 stars mostly within 200 pc, complementing extensive imaging campaigns that are observing their disks at optical, infrared, and millimeter wavelengths and revealing structures and planets.

EUV Beam-Foil Spectra of Scandium, Vanadium, Chromium, Manganese, Cobalt, and Zinc

Beam-foil extreme-ultraviolet spectra of Sc, V, Cr, Mn, Co and Zn are presented that provide survey data of a single element exclusively. Various details are discussed in the context of line intensity ratios, yrast transitions, delayed spectra and peculiar properties of the beam-foil light source.

Unveiling the magnetic and transport properties of La0.5Sr0.5Co1−xVxO3−δ (x = 0, 0.01, 0.02 and 0.1)

La0.5Sr0.5CoO3−δ system displaying coexistence of metallicity and ferromagnetism, and the interplay between distinct spin states of Co ions has gained significant attention from the fundamental as well as the applications point of view. In this regard, the effect of V5+ doping on the dynamics of spin and oxidation states of Co ions in the La0.5Sr0.5CoO3−δ system has been studied using structural, X-ray photoemission spectroscopy, magnetic and transport measurements. The La0.5Sr0.5Co1−xVxO3−δ (x = 0, 0.01, 0.02 and 0.1) series was prepared by conventional solid-state reaction method and its chemical homogeneity was established by inductively coupled plasma mass spectroscopy. The increase of lattice parameters/volume with increasing V5+ content in rhombohedrally crystallized (R3-c) samples is attributed to the presence of Co2+ ions . The presence of Co2+ ions and the reduction of Co3+ ion concentration with V substitution is verified from the results of core-level photoemission spectra of Co. Detailed magnetic measurements show an increase in Curie temperature, effective magnetic moment, soft magnetic nature and suggesting strengthening of underlying magnetic interactions. As a result of multiple oxidation states of Co ions and the delocalization of electrons, rise in the conductivity is noticed. Such enhancement in the conductivity and ferromagnetic ordering temperature, simultaneously, with V doping implies a strong coupling between spin and charge degrees of freedom. To understand the underlying mechanism more clearly, different possible scenarios have been discussed. The most appropriate scenario i.e., the conversion of Co3+ ions into Co2+ ions and admixture of Co4+ ion spin states with V5+ doping was found to be consistent with all the experimental observations.

11-μs time-resolved, continuous dual-comb spectroscopy with spectrally filtered mode-locked frequency combs

Broadband dual-comb spectroscopy (DCS) based on portable mode-locked fiber frequency combs is a powerful tool for in situ, calibration-free, multi-species spectroscopy. While the acquisition of a single spectrum with mode-locked DCS typically takes microseconds to milliseconds, the applications of these spectrometers have generally been limited to systems and processes with time changes on the order of seconds or minutes due to the need to average many spectra to reach a high signal-to-noise ratio (SNR). Here, we demonstrate high-speed, continuous, fiber mode-locked laser DCS with down to 11 μs time resolution. We achieve this by filtering the comb spectra using portable Fabry–Perot cavities to generate filtered combs with 1 GHz tooth spacing. The 1 GHz spacing increases the DCS acquisition speed and SNR for a given optical bandwidth while retaining a sufficient spacing to resolve absorption features over a wide range of conditions. We measure spectra of methane inside a rapid compression machine throughout the 16 ms compression cycle with 133 cm−1 bandwidth (4000 comb teeth) and 1.4 ms time resolution by spectrally filtering one of the combs. By filtering both combs, we measured a single-shot, 25 cm−1 (750 comb teeth) spectrum of CO around 6330 cm−1 in 11 μs. The technique enables simultaneously high-speed and high-resolution DCS measurements, and can be applied anywhere within the octave-spanning spectrum of robust and portable fiber mode-locked frequency combs.

The O K−2V spectrum of CO: the influence of the second core-hole

Using synchrotron radiation in the tender X-ray regime, a photoelectron spectrum showing the formation of single site double-core-hole pre-edge states, involving the K shell of the O atom in CO, has been recorded by means of high-resolution electron spectroscopy. The experimentally observed structures have been simulated, interpreted and assigned, employing state-of-the-art ab initio quantum chemical calculations, on the basis of a theoretical model, accounting for their so-called direct or conjugate character. Features appearing above the double ionization threshold have been reproduced by taking into account the strong mixing between multi-excited and continuum states. The shift of the σ* resonance below the double ionization threshold, in combination with the non-negligible contributions of multi-excited configurations in the final states reached, gives rise to a series of avoided crossings between the different potential energy curves.

Свободное вращение простых молекул и характеристические температуры в стеклообразных полимерах

Purely rotational spectra of CO and HCl molecules added as a probe to polypropylene (PP) and polyvinyl chloride (PVC) were obtained and analyzed. It is shown that the shape of the bands of these spectra, which reflects the degree of disturbance of the rotational motion, is strongly influenced by the local dynamics of the polymer matrix. From the change in the integrated intensity of absorption with the temperature were found temperatures of the transition from free rotation of CO and HCl molecules to their libration, as well as the temperatures of the onset of defrosting of the conformational mobility of the chains of PP and PVC macromolecules.

The binary absorption coefficients for H2 + CO2 mixtures in the 2.12–2.35 µm spectral region determined by CRDS and by semi-empirical calculations

Spectra of CO2 + H2 mixtures have been recorded at room temperature by using the cavity ring down technique, for four spectral intervals in the 2.12–2.35 µm CO2 transparency window which is within the (1-0) band of H2. The binary coefficients BCO2−H2+BH2−CO2 have been retrieved from the spectra recorded at different pressures after subtraction of the CO2 monomer contribution and of the H2-H2 and CO2-CO2 collision induced absorptions (CIAs). In order to reduce the uncertainties, new measurement of the pure H2 CIA, the main subtracted contribution, at the percent level are also reported. The new set of experimental binary coefficients is compared to values provided by semi-empirical calculations made with the assumption of an isotropic CO2-H2 interaction potential and neglecting the short-range interaction-induced electric dipole. This comparison shows the limits of using such a model, which is the only one available, in that spectral region.

Spatially Resolving the Inner Gaseous Disc of the Herbig Star 51 Oph through its CO Ro-vibration Emission

Near-infrared interferometry gives us the opportunity to spatially resolve the circumstellar environment of young stars at sub-astronomical-unit (au) scales, which a standalone telescope could not reach. In particular, the sensitivity of GRAVITY on the VLTI allows us to spatially resolve the CO overtone emission at 2.3 microns. In this article, we present a new method of using the model of the CO spectrum to reconstruct the differential phase signal and extract the geometry and size of the emitting region.

Resonance Raman Scattering Spectra of Co(II)- and Cu-5,10,15,20-Tetrakis[4-(N-methylpyridyl)]porphyrin in the dd Excited State and Mechanisms of Its Deactivation in a Solution and in Complexes with DNA

Resonance Raman scattering (RRS) spectra of the complexes of 5,10,15,20-tetrakis[4-(N-methylpyridyl)]porphyrin with Co(II) and Cu(II) (CoIITMpyP4 and CuTMpyP4) in various solvents and in complexes with DNA are studied. Under nanosecond pulsed excitation, additional lines have been found in the RRS spectra of CoIITMpyP4 in a dimethylformamide (DMF) solution containing formic acid as an impurity and in a complex with DNA. At the same time, such lines are absent in the spectra of CoIITMpyP4 in pure DMF, dimethyl sulfoxide, water, and alcohols under the same excitation conditions. To interpret the experimental data, we have calculated the structure and vibrations of the solvate complexes of CoIITMpyP4 and CuTMpyP4 with water, methanol, and formic acid in the ground and in excited states. Based on the obtained data, additional lines in the Raman spectra are assigned to the dd excited state corresponding to the d(z2) → d(x2 – y2) transition, the lifetime of which increases with the formation of complexes of CoIITMpyP4 with formic acid. According to the calculation results, this correlates with a decrease in rate constant kic of the internal conversion due to an increase in energy gap ΔE between the ground and dd states of CoIITMpyP4. A decrease in the kic value in the case of binding of CoIITMpyP4 and CuTMpyP4 to DNA is caused by the additional interaction of the extra-ligand water molecule with one of its bases directly or via several water molecules immobilized on DNA surface. This complicates the conformational rearrangement of the water molecule in the dd excited state, which gives rise to an increase in the ΔE value.

Accurate prediction of core-level spectra of radicals at density functional theory cost via square gradient minimization and recoupling of mixed configurations.

State-specific orbital optimized approaches are more accurate at predicting core-level spectra than traditional linear-response protocols, but their utility had been restricted due to the risk of "variational collapse" down to the ground state. We employ the recently developed square gradient minimization [D. Hait and M. Head-Gordon, J. Chem. Theory Comput. 16, 1699 (2020)] algorithm to reliably avoid variational collapse and study the effectiveness of orbital optimized density functional theory (DFT) at predicting second period element 1s core-level spectra of open-shell systems. Several density functionals (including SCAN, B3LYP, and ωB97X-D3) are found to predict excitation energies from the core to singly occupied levels with high accuracy (≤0.3 eV RMS error) against available experimental data. Higher excited states are, however, more challenging by virtue of being intrinsically multiconfigurational. We thus present a configuration interaction inspired route to self-consistently recouple single determinant mixed configurations obtained from DFT, in order to obtain approximate doublet states. This recoupling scheme is used to predict the C K-edge spectra of the allyl radical, the O K-edge spectra of CO+, and the N K-edge of NO2 with high accuracy relative to experiment, indicating substantial promise in using this approach for the computation of core-level spectra for doublet species [vs more traditional time dependent DFT, equation of motion coupled cluster singles and doubles (EOM-CCSD), or using unrecoupled mixed configurations]. We also present general guidelines for computing core-excited states from orbital optimized DFT.

The GRAVITY young stellar object survey

Context. Studies of the dust distribution, composition, and evolution of protoplanetary disks provide clues for understanding planet formation. However, little is known about the innermost regions of disks where telluric planets are expected to form. Aims. We aim constrain the geometry of the inner disk of the T Tauri star RY Lup by combining spectro-photometric data and interferometric observations in the near-infrared (NIR) collected at the Very Large Telescope Interferometer. We use PIONIER data from the ESO archive and GRAVITY data that were obtained in June 2017 with the four 8m telescopes. Methods. We use a parametric disk model and the 3D radiative transfer code MCFOST to reproduce the spectral energy distribution (SED) and match the interferometric observations. MCFOST produces synthetic SEDs and intensity maps at different wavelengths from which we compute the modeled interferometric visibilities and closure phases through Fourier transform. Results. To match the SED from the blue to the millimetric range, our model requires a stellar luminosity of 2.5 L⊙, higher than any previously determined values. Such a high value is needed to accommodate the circumstellar extinction caused by the highly inclined disk, which has been neglected in previous studies. While using an effective temperature of 4800 K determined through high-resolution spectroscopy, we derive a stellar radius of 2.29 R⊙. These revised fundamental parameters, when combined with the mass estimates available (in the range 1.3–1.5 M⊙), lead to an age of 0.5–2.0 Ma for RY Lup, in better agreement with the age of the Lupus association than previous determinations. Our disk model (that has a transition disk geometry) nicely reproduces the interferometric GRAVITY data and is in good agreement with the PIONIER ones. We derive an inner rim location at 0.12 au from the central star. This model corresponds to an inclination of the inner disk of 50°, which is in mild tension with previous determinations of a more inclined outer disk from SPHERE (70° in NIR) and ALMA (67 ± 5°) images, but consistent with the inclination determination from the ALMA CO spectra (55 ± 5°). Increasing the inclination of the inner disk to 70° leads to a higher line-of-sight extinction and therefore requires a higher stellar luminosity of 4.65 L⊙ to match the observed flux levels. This luminosity would translate to a stellar radius of 3.13 R⊙, leading to an age of 2–3 Ma, and a stellarmass of about 2 M⊙, in disagreement with the observed dynamical mass estimate of 1.3–1.5 M⊙. Critically, this high-inclination inner disk model also fails to reproduce the visibilities observed with GRAVITY. Conclusions. The inner dust disk, as traced by the GRAVITY data, is located at a radius in agreement with the dust sublimation radius. An ambiguity remains regarding the respective orientations of the inner and outer disk, coplanar and mildly misaligned, respectively.As our datasets are not contemporary and the star is strongly variable, a deeper investigation will require a dedicated multi-technique observing campaign.

RETRACTED ARTICLE: Revisiting the Evolution of IR Spectra of CO Adsorbed on Au Nanoparticles Supported on Non-reducible Supports

Gold surfaces and nanoparticles have commonly been investigated by IR spectroscopy using carbon monoxide as a molecular probe. An evolution of the IR spectra with time under CO was reported in some cases and tentatively assigned to geometrical effects (e.g. surface reconstruction or particle restructuring) or electronic effects, e.g. gold becoming negatively charged following support reduction. We report here an investigation of the evolution of the IR spectrum of CO adsorbed at 50 °C in the case of Au nanoparticles supported on non-reducible silica and alumina supports. The evolution of the carbonyl IR band signal, proposed to arise mostly from Au particle restructuring, was clearly observed. In addition, the formation of hydrogenocarbonates species on the alumina reemphasized that Au nanoparticles are somewhat active for CO dissociation via Boudouard reaction near room temperature, leading to some deposition of carbon. Water could not prevent restructuring, while O2 prevented irreversibly the reconstruction, which could even be reversed when O2 was introduced on an already restructured sample. It is hypothesized that the role of O2 would be to remove the deposited elemental carbon that otherwise stabilize reconstructed Au. These results emphasize the complexity of the parameters affecting the restructuration of Au surfaces induced by CO and the difficulty in interpreting IR spectra of CO adsorption on Au-based materials.

Dense gas formation in the Musca filament due to the dissipation of a supersonic converging flow

Observations with theHerschelSpace Telescope have established that most star forming gas is organised in filaments, a finding that is supported by numerical simulations of the supersonic interstellar medium (ISM) where dense filamentary structures are ubiquitous. We aim to understand the formation of these dense structures by performing observations covering the12CO(4→3),12CO(3→2), and various CO(2–1) isotopologue lines of the Musca filament, using the APEX telescope. The observed CO intensities and line ratios cannot be explained by PDR (photodissociation region) emission because of the low ambient far-UV field that is strongly constrained by the non-detections of the [C II] line at 158μm and the [O I] line at 63μm, observed with the upGREAT receiver on SOFIA, as well as a weak [C I] 609μm line detected with APEX. We propose that the observations are consistent with a scenario in which shock excitation gives rise to warm and dense gas close to the highest column density regions in the Musca filament. Using shock models, we find that the CO observations can be consistent with excitation by J-type low-velocity shocks. A qualitative comparison of the observed CO spectra with synthetic observations of dynamic filament formation simulations shows a good agreement with the signature of a filament accretion shock that forms a cold and dense filament from a converging flow. The Musca filament is thus found to be dense molecular post-shock gas. Filament accretion shocks that dissipate the supersonic kinetic energy of converging flows in the ISM may thus play a prominent role in the evolution of cold and dense filamentary structures.

Molecular Clouds Surrounding Supernova Remnant G43.9+1.6: Associated and Nonassociated

Abstract Many supernova remnants (SNRs) are considered to evolve in molecular environments, but the associations between SNRs and molecular clouds (MCs) are often unclear. Being aware of such ambiguity, in our study, we report on the molecular environment toward SNR G43.9+1.6 through CO line observations. We investigated the correlations between the SNR and MCs at different velocities, and found two velocity components, i.e., ∼5 km s−1 and ∼50 km s−1, showing spatial correlations with the remnant. However, no kinematic evidence of a disturbance was found for the ∼5 km s−1 velocity component. Furthermore, at the distance of the ∼5 km s−1 velocity component, either near or far, the derived physical parameters are unreasonable. We conclude that the SNR is not associated with the ∼5 km s−1 velocity component, and their spatial correlation is just a chance correlation. For the ∼50 km s−1 velocity component, kinematic evidence of disturbances, as well as the spatial correlation, indicate that it is associated with the SNR. We found that all the CO spectra extracted from the molecular clumps distributed along the border of the remnant are with broadened components presented, which can be fitted by Gaussian functions. Through further analysis, we suggest that the SNR is at a near kinematic distance of about 3.1 kpc.

Computational investigation of flavonol-based GLP-1R agonists using DFT calculations and molecular docking

Glucagon-like peptide 1 receptor agonists (GLP-1RA) have excellent performance in the treatment of diabetes, but the drugs used in the clinic are all macromolecular peptide injections. Therefore, non-peptide small molecule drugs that can be taken orally have become the research and development trend of GLP-1RA. Some flavonols have been proved to be small molecule GLP-1RA. We have conducted DFT and molecular docking studies on reported flavonol-based non-peptide GLP-1RA. Flavone, flavonol, 4′-hydroxyflavonol, 3′,4′-dihydroxyflavonol and quercetin were investigated at B3LYP [6-311G (d, p)/6-311+G (d, p)/6-311++G (d, p)] levels in gas and water phase. The calculation was performed on their equilibrium structures and harmonic frequencies in gas and water phase, respectively. Vibration frequency and infrared spectrum of OH and CO can be used to identify structural analogs of this type of compounds. The topological properties of the IMHB for flavonols have been investigated using the atoms-in-molecules (AIM) approach. Electrostatic potential (ESP), conceptual density functional theory (CDFT) and condensed dual descriptor (CDD) were used for molecular reactivity studies. The preliminary investigations of binding details between flavonols and GLP-1R are explored by molecular docking technology. The results of this study are expected to aid the design and analyze of new flavonol-based small molecule GLP-1RA with improved properties.

Simulation of vibrationally resolved electronic spectra of combustion intermediates at high temperature

Because of high temperature, the experimental diagnosis for the combustion intermediates of hydrocarbon fuel is still a great challenge. In this letter, we propose a method to detect qualitatively the combustion intermediates by introducing temperature into the expression of vibrationally resolved electronic spectrum, which is based on the relationship between molecular structure and its spectrum. Using this method, the fine electronic spectra of CO+ and N2+ molecules are simulated, and the results reproduce their experimental ones very well, indicating the reliability of this method. Further, the electronic spectra of combustion intermediates C2N, NO2, OOH and HCO are predicted and the main vibrational bands are assigned. This work provides theoretical guidance for the qualitative detection of hydrocarbon fuel combustion intermediates under high temperature.

Bound State Solution of Radial Schrodinger Equation for the Quark–Antiquark Interaction Potential

This work analytically solved the radial Schrodinger equation with an exponential, generalised, anharmonic Cornell potential using the series expansion method. It also obtained the bound state energy spectra. Through suitable adjustments to the potential parameters, the well-known potential models, such as the pseudoharmonic and Kratzer potentials, were deduced. With the potential parameters also adjusted, the energy spectra for the pseudoharmonic and Kratzer potentials were obtained as special cases. The numerical values of the energy spectra for CO, NO, CH and N2 diatomic molecules were computed for different quantum numbers, n and l, respectively. In addition, with the application of the spectra, an expression for the mass spectra of heavy quarkonium systems (charmonium and bottomonium) was obtained. The results agree with the experimental and theoretical studies in previous works.

Bone lesions: Benign, malignant and inflammatory; A Histopathological study

Background: The spectrum of bone lesions include inflammatory, neoplastic, degenerative and metabolic diseases. Histopathology is a confirmatory evidence for bone lesions and helps arrive at a diagnosis and plan further prognosis and management. A proper execution from technique (radio-guided or surgical), choice of sections from the lesion and proper management of specimen is the requirement for accuracy of diagnosis and further management. Aims and objectives: To analyse the histo-pathological spectrum of bone lesions and co relating it with demographic details and radiological findings. Results: 100 bone biopsies received in the Department of Pathology between September 2015 to September 2017. They were routinely processed after decalcification. Out of 100 cases, 55 non-neoplastic lesions and 45 neoplastic lesions were reported. Around 10 cases were inconclusive due to inadequacy of biopsy sample. Osteochondroma was the most common benign lesion. Osteosarcoma and chondrosarcoma were the most common malignant lesion, with equal incidence. Chronic osteomyelitis was the most common non neoplastic lesion. The lesions occurred most commonly below the age group of 20 years with a male preponderance. Femur was the most common bone involved and metaphysis was the most common anatomical site of lesion. Conclusion: A detailed histo-pathological interpretation of bone lesions, along with history, radiological and other relevant investigations are important for the patient’s treatment and the further management including the follow up.

Saturation and self-absorption effects in the angle-dependent 2p3d resonant inelastic X-ray scattering spectra of Co3+

Angle-dependent 2p3d resonant inelastic X-ray scattering spectra of a LaCoO3 single crystal and a 55 nm LaCoO3 film on a SrTiO3 substrate are presented. Theoretical calculation shows that, with ∼20 meV resolved Co 2p3d resonant inelastic X-ray scattering (RIXS), the excited states of the isotropic 1A1g(Oh) ground state are split by 3d spin-orbit coupling, which can be distinguished viatheir angular dependence. However, strong self-absorption and saturation effects distort the spectra of the LaCoO3 single crystal and limit the observation of small angular dependence. In contrast, the RIXS on 55 nm LaCoO3 shows less self-absorption effects and preserves the angular dependence of the excited states.