IR Absorption Spectroscopy Research Articles

Room-temperature atomic layer deposition of iron oxide using plasma excited humidified argon

Room-temperature atomic layer deposition (RT-ALD) of iron oxide is developed with a precursor of bis(N, N′-diisopropyl-propionamidinate)iron [(DIPPA)2Fe] and plasma excited humidified Ar. Saturated conditions of (DIPPA)2Fe and plasma excited humidified Ar exposures at room temperature (23–25 °C) are investigated by in situ IR absorption spectroscopy for finding the RT-ALD process condition. Using the designated process, the growth per cycle of the iron oxide RT-ALD is confirmed as 0.15 nm/cycle based on the film thicknesses measured by the spectroscopic ellipsometer. The x-ray photoelectron spectroscopy suggests that the stoichiometry of the deposited iron oxide is closed to that of Fe2O3. The grown film is composed of partly crystallized iron oxides, confirmed by cross-sectional TEM and AFM. The RT deposited iron oxide exhibits a magnetic volume susceptibility of 1.52, which implies the applicability of the present coating for magnetic drug delivery. We discuss the surface reaction with the IR absorption spectroscopy and the quartz crystal microbalance. The (DIPPA)2Fe molecule is suggested to adsorb on the Fe2O3 surface with mixed first- and second-order reactions at RT. It is also suggested that amidinate ligands in (DIPPA)2Fe are released in the course of the adsorption and the remaining ligands are oxidized by the plasma excited humidified Ar. The RT iron oxide deposition is demonstrated, and the reaction mechanism of room-temperature ALD is discussed in this paper.

Electrosynthesis of gold nanocomposites based on copolymer of 1-vinyl-1,2,4-triazol with crotonic acid

In this work, we have synthesized and discussed the results of electrosynthesis of metal-polymer nanocomposites of gold. Nanocoatings were made on pure iron and steel electrodes by combining the process of electropolymerization of 1-vinyl-1.2.4-triazole with crotonic acid and cathodic deposition of gold. Using UV, IR and atomic absorption spectroscopies, X-ray phase analysis, as well as thermogravimetric and elemental analyses, the structure and composition of the synthesized nanocomposites and nanocomposite coatings were studied.

Resonance Raman: A powerful tool to interrogate carotenoids in biological matrices.

Resonance Raman spectroscopy is one of the most powerful techniques in analytical science due to its molecular selectivity, high sensitivity, and the fact that, in contrast to IR absorption spectroscopy, the presence of water does not hamper or mask the results. Originating in physics and chemistry, the use of Raman spectroscopy has spread and now includes a variety of applications in different disciplines, including biology. In this chapter, we introduce the basic principles of Raman and resonance Raman scattering, and show resonance Raman can be applied to study carotenoid molecules, in complex biological or chemical matrices. We describe the type of information that can be extracted from resonance Raman spectra, illustrating the power of this method by a series of example applications.

Hydrogenation of Accreting C Atoms and CO Molecules–Simulating Ketene and Acetaldehyde Formation Under Dark and Translucent Cloud Conditions

Abstract Simple and complex organic molecules (COMs) are observed along different phases of star and planet formation and have been successfully identified in prestellar environments such as dark and translucent clouds. Yet the picture of organic molecule formation at those earliest stages of star formation is not complete and an important reason is the lack of specific laboratory experiments that simulate carbon atom addition reactions on icy surfaces of interstellar grains. Here we present experiments in which CO molecules as well as C and H atoms are codeposited with H2O molecules on a 10 K surface mimicking the ongoing formation of an “H2O-rich” ice mantle. To simulate the effect of impacting C atoms and resulting surface reactions with ice components, a specialized C-atom beam source is used, implemented on SURFRESIDE3, an ultra-high vacuum cryogenic setup. Formation of ketene (CH2CO) in the solid state is observed in situ by means of reflection absorption IR spectroscopy. C18O and D isotope labeled experiments are performed to further validate the formation of ketene. Data analysis supports that CH2CO is formed through C-atom addition to a CO molecule, followed by successive hydrogenation transferring the formed :CCO into ketene. Efficient formation of ketene is in line with the absence of an activation barrier in C+CO reaction reported in the literature. We also discuss and provide experimental evidence for the formation of acetaldehyde (CH3CHO) and possible formation of ethanol (CH3CH2OH), two COM derivatives of CH2CO hydrogenation. The underlying reaction network is presented and the astrochemical implications of the derived pathways are discussed.

Influence of the lithium niobate crystals composition on mobility of Н+ and Li+ ions in the temperature range 300–450 K

IR absorption spectroscopy and electrical conductivity have been studied in a series of lithium niobate crystals. We have established that mobility of Li+ ion sharply increases when a crystal approaches stoichiometric composition. This is especially true along the polar direction of a crystal. We have also established that doping of lithium niobate crystals with under-threshold concentrations of non-photorefractive Mg and Zn substantially decreases mobility of Н+ ions.

Colloidal Cu-Zn-Sn-Te Nanocrystals: Aqueous Synthesis and Raman Spectroscopy Study.

Cu-Zn-Sn-Te (CZTTe) is an inexpensive quaternary semiconductor that has not been investigated so far, unlike its intensively studied CZTS and CZTSe counterparts, although it may potentially have desirable properties for solar energy conversion, thermoelectric, and other applications. Here, we report on the synthesis of CZTTe nanocrystals (NCs) via an original low-cost, low-temperature colloidal synthesis in water, using a small-molecule stabilizer, thioglycolic acid. The absorption edge at about 0.8–0.9 eV agrees well with the value expected for Cu2ZnSnTe4, thus suggesting CZTTe to be an affordable alternative for IR photodetectors and solar cells. As the main method of structural characterization multi-wavelength resonant Raman spectroscopy was used complemented by TEM, XRD, XPS as well as UV-vis and IR absorption spectroscopy. The experimental study is supported by first principles density functional calculations of the electronic structure and phonon spectra. Even though the composition of NCs exhibits a noticeable deviation from the Cu2ZnSnTe4 stoichiometry, a common feature of multinary NCs synthesized in water, the Raman spectra reveal very small widths of the main phonon peak and also multi-phonon scattering processes up to the fourth order. These factors imply a very good crystallinity of the NCs, which is further confirmed by high-resolution TEM.

Synthesis and in vitro biochemical properties, DNA binding and DNA cleavage ability of copper complexes of hydroxyflavone derivatives of novel organosulfur compounds as therapeutic agent

Novel and synthetically essential flavonoids compounds containing the organosulfur moiety from Schiff bases, as well as their copper complexes, were synthesized from chrysin and 2-(phenylthio)aniline. These complexes were characterized using elemental analysis, mass spectrometry, electronic absorption spectroscopy, IR, 1H, and 13C NMR spectroscopy techniques. All the Cu(II) complexes exhibit square planar geometry. The in vitro antimicrobial activities of the investigated compounds were tested against the bacterial species, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, and Klebsiella pneumoniae and fungal species, Aspergillus niger, Fusarium solani, Culvularia lunata, Rhizoctonia bataicola, and Candida albicans by serial dilution method. The DNA binding and DNA cleavage properties of copper complexes were studied. Free radical scavenging, superoxide dismutase, glutathione peroxidase, and antioxidant activities of the copper complexes have also been studied. In addition, using the egg albumin process, the in vitro anti-inflammatory efficacy of metal chelates was examined. Anti-tuberculosis and α-glucosidase inhibition activity were carried out from the prepared metal complexes. The flavonoid compounds containing the organosulfur moiety of Cu(II) complexes (1–8) exhibited better therapeutic agent.

The origin of the structural transition in double-perovskite manganite PrBaMn2O6

Double manganite PrBaMn2O6 with ordered alternate stacking of PrMnO3/BaMnO3 layers attracts a special interest due to presence of two magnetic phase transitions close to room temperature; that makes it perspective magnetocaloric and magnetoresistive material. Besides the magnetic phase transition, the structural transition accompanied with the elongation of the a-axis and the contraction of the c-axis was experimentally detected. The origin of structural phase transition is studied by X-ray powder diffraction, X-ray photoelectron spectroscopy (XPS), IR absorption spectroscopy, magnetometry and dynamical mean-field theory (DMFT) for electronic structure calculations. It is found that the structural phase transition is caused by splitting of eg-doublet states due to the tendency towards orbital ordering at the metal-insulator phase transition.

New Method for Synthesis of Substituted N-Borylated Dipeptides Based on Acetonitrile Derivative of the closo-Dodecaborate Anion

A new multistage synthesis of the N-borylated dipeptide B12-PheGlyOH has been proposed. The approach is based on the reaction of nucleophilic addition of amino acid derivatives to the [B12H11NCCH3]– anion. The products of each stage have been characterized by multinuclear NMR spectroscopy, IR absorption spectroscopy, and ESI mass spectrometry.

The Features of Infrared Absorption of Boron‐Doped Silicon

Herein, the influence of heat treatment at 400 °C on the spectrum of boron intracenter transitions in silicon using IR absorption spectroscopy is investigated. In the transition region from the ground 1Γ8+ state associated with the p3/2 valence band of Si to the odd‐parity excited states of boron, a new absorption line with its maximum at 261.3 cm−1 is observed in the thermally treated boron‐doped Cz‐Si. Oxygen is a component of defect that is responsible for the detected absorption line. Perturbation of boron atoms due to the inhomogeneous stress effect from neighboring oxygen atoms results in a frequency shift in the main boron transition. The defect associated with 261.3 cm−1 line is also observed in as‐grown silicon. The defect disappears during annealing at 550 °C. The concentration of defects and binding energy of the 1Γ8+ ground state are estimated assuming that the line observed belongs to the transition of boron 1Γ8+ → 2Γ8−, subjected to the perturbation from a neighboring oxygen atom.

Experimental Investigation of the Thermal Decomposition Pathways and Kinetics of TATB by Isotopic Substitution

AbstractReal‐time measurements of the product gases arising from the thermal decomposition of triamino‐trinitro benzene (TATB), its deuterated analogue, and plastically bonded TATB (LX‐17) are presented in this study. Gas‐phase decomposition products are identified by IR absorption spectroscopy. The frequency shifts in rovibrational spectra due to isotopic substitution and the change in rate of formation of decomposition products due to the kinetic‐isotope‐effect (KIE) help elucidate the decomposition pathways. The formation of H2O precedes other molecules (e. g., HCN, HNCO) during decomposition. After the concentrations of HCN and HNCO molecules reach a peak, their amounts gradually decrease. The concentrations of the other decomposition products (e. g., NH3 and CO2) rapidly rise after an induction period, which is attributed to the presence of autocatalytic reactions. The trends of chemical evolution are similar for all the samples, but their kinetic behaviors are different. This indicates the rates of consistent pathways are changed during thermal decomposition. The kinetics of deuterated TATB decomposition is slower than that of unsubstituted TATB due to the KIE (kH/kD∼1.41). The rate of LX‐17 decomposition is slightly lower than unsubstituted TATB (kTATB/kLX‐17∼1.15). The KIE is more pronounced during the early stage of decomposition, which is attributed to the first steps of TATB decomposition involving water formation (i. e., H vs D transfer). The KIE slows down the formation of all gases, including those lacking hydrogen (e. g., CO2). These results suggest the TATB thermal decomposition mechanism might involve a series of pathways rather than a set of independent and parallel reactions.

Detecting Trace Gases at PPM Levels with Low Temperature Plasma Optical Emission Spectroscopy

Detecting Trace Gases at PPM Levels with Low Temperature Plasma Optical Emission Spectroscopy

Effect of water incorporation on the ionic conduction properties of the solid electrolyte material Rb2Ti2O5.(H2O)x

Previous work has demonstrated the accumulation of negative charges on the anode side of the ion conductor Rb2Ti2O5 when placed under voltage between two metallic electrodes. The nature of these accumulated species and of the conducting ions is investigated by a combination of thermogravimetric analysis (TGA), Xray diffraction, dielectric response measurements, charge distribution, IR absorption spectroscopy and nuclear magnetic resonance (NMR) measurements. TGA shows that the as-grown samples have incorporated a considerable amount of water (up to 0.35 H2O per unit cell) that is eliminated at two different temperature thresholds. However, no significant variation of the lattice parameters is observed by X-Ray diffraction. A strong dependence of the dielectric properties and of the accumulated charge density on the water content is demonstrated. All the results point towards a mechanism of proton and hydroxide conduction associated with a change of valence for titanium.

Synthesis, X-ray structure and biological activity of mono- and dinuclear copper complexes derived from N-{2-[(2-diethylamino(alkyl)imino)-methyl]-phenyl}-4-methyl-benzenesulfonamide

A series of copper(II) complexes with new Schiff bases, namely N-{2-[(2-diethylamino(alkyl)imino)-methyl]-phenyl}-4-methylbenzenesulfonamide [alkyl = ethyl (HL1) or propyl (HL2)], were synthesized using copper acetate or chloride and characterized by elemental analysis, IR and X-ray absorption spectroscopy, and single-crystal X-ray diffraction. The coordination geometry around the Cu(II) ion in Cu(L1)2 and Cu(L2)2 was studied by X-ray absorption spectroscopy. The crystal structures of copper(II) complexes with L1 ligand synthesized from copper chloride and copper acetate with addition of sodium azide have been determined by X-ray diffraction. The azomethines and all copper(II) complexes have been screened for their antibacterial, protistocidal, and fungistatic activities against Penicillium italicum, Colpoda steinii, Escherichia coli 078, and Staphylococcus aureus P-209.

Synthesis, Spectroscopic Properties and Redox Behavior Kinetics of Rare-Earth Bistetrakis-4-[3-(3,4-dicyanophenoxy)phenoxy]phthalocyaninato Metal Complexes with Er, Lu and Yb.

Novel bistetrakis-4-[3-(3,4-dicyanophenoxy)phenoxy]phthalocyaninato of complexes erbium, lutetium and ytterbium were synthesized using a template fusion method to prevent any polymerization process. The complexes were separated from the reaction mixtures and characterized by NMR, IR and electron absorption spectroscopy. The spectroscopic properties of the metal phthalocyaninates in chloroform, acetone and tetrahydrofuran were studied. The regular bathochromic shift in the Er–Yb–Lu series was determined. In acetone medium all the complexes obtained were found to exist in an equilibrium state between neutral and reduced forms. The linearity of Lambert-Bouger-Beer curves makes it possible to study the kinetics of redox processes in the presence of phenylhydrazine and bromine. The lutetium complex showed better reducing properties and turned fully into the reduced form, while the erbium and ytterbium ones changed only partially. Upon oxidizing all the phthalocyaninates transformed into a mixture of oxidized and neutral-radical forms. The extinction coefficients and effective redox constants were calculated.

Hydrothermal Synthesis and Structural Investigation of a Crystalline Uranyl Borosilicate

The relevance of multidimensional and porous crystalline materials to nuclear waste remediation and storage applications has motivated exploratory research focused on materials discovery of compounds, such as actinide mixed-oxoanion phases, which exhibit rich structural chemistry. The novel phase K1.8Na1.2[(UO2)BSi4O12] has been synthesized using hydrothermal methods, representing the first example of a uranyl borosilicate. The three-dimensional structure crystallizes in the orthorhombic space group Cmce with lattice parameters a = 15.5471(19) Å, b = 14.3403(17) Å, c = 11.7315(15) Å, and V = 2615.5(6) Å3, and is composed of UO6 octahedra linked by [BSi4O12]5− chains to form a [(UO2)BSi4O12]3− framework. The synthesis method, structure, results of Raman, IR, and X-ray absorption spectroscopy, and thermal stability are discussed.

State-resolved rotational distributions and collision dynamics of CO molecules made in a tunable optical centrifuge.

State-resolved distributions and collision dynamics of optically centrifuged CO molecules with orientated angular momentum are investigated by probing the CO J = 29-80 rotational levels using high-resolution transient IR absorption spectroscopy. An optical centrifuge with tunable bandwidth is used to control the extent of rotational excitation in the sample. The rotational distributions are inverted with a maximum population in J = 62. Rotational levels with J > 62 have populations that correlate with the intensity profile of the optical trap. The full bandwidth trap excites CO up to the J = 80 level, while J = 67 is the highest level observed in the reduced bandwidth trap. Polarization-sensitive transient spectroscopy shows that the initial orientational anisotropy is r = 0.8 for levels with J ≥ 55, while anisotropy values are near r = 0.4 for levels with J < 50. The rotational distribution for J > 50 is broadened slightly by collisions, consistent with small |ΔJ| propensity rules for rotational energy transfer. Doppler-broadened line profiles show that the J = 60-80 levels have translational temperatures near Ttrans = 300 K and that these temperatures remain constant for as much as 24 gas kinetic collisions. Doppler linewidths for levels with J < 60 are broadened by non-resonant rotation-to-translation energy transfer. Kinetic analysis of transient signals shows that collisions with thermal bath molecules are the predominant relaxation pathway.

Reducible oxide and allotropic transition induced by hydrogen annealing: synthesis routes of TiO2 thin films to tailor optical response

Optical properties of hydrogenated TiO2 thin films deposited by the ion beam sputtering method are reported. By reducing the oxide by hydrogenation in situ (during deposition) and ex situ (by means of posterior thermal annealing) a controlled phase modification allows to manipulate optical properties to improve photoactivity for solar energy conversion and catalytic applications. The hydrogenation procedure prompts remarkable structural changes and optical properties of the TiO2 hierarchical thin films. Photoemission electron spectroscopy (XPS) results show the presence of titanium in Ti4+ into Ti3+ state of oxidation, i.e., compatible with oxygen vacancies and titanium interstitials. Vibrational properties inspected by IR absorption and Raman spectroscopy allowed identifying potentially catalytic sites and vibration modes associated with hydrogen. The vibrational spectra show that both in situ and ex situ hydrogenation routes contribute to prompt (dis)order in the films, involving the presence of anatase crystalline phase embedded in an amorphous matrix or mixed-phase (anatase + rutile) crystalline TiO2. To avoid debate about the TiO2 theoretical (indirect) and expected and measured (direct, normally reported) optical gap (Egap), the absorption coefficient spectra were analyzed by a recently developed method based on the Boltzmann sigmoidal function. From these analyses, conclusions about defects states prompted by the hydrogenation processes are presented.

In English

In this paper, we used high-resolution IR absorption spectra to investigate 1D and 2D polaritons in periodical 2D macroporous silicon structures with nano-coatings of SiO2 and CdS, ZnO nanoparticles. The application of high-resolution IR absorption spectroscopy resulted in detection of dipole-active TO vibrations, photon splitting and giant two-polar absorption oscillations with amplitudes of ±107arb.un. As a result, the dispersion law in yz surfaces of macropores change to z direction along macropores. It means additional degree of freedom as vertically polarized light in z direction and horizontally polarized light in x direction resulted in beams splitting and two-photon interference - Hong-Ou-Mandel effect. In our case, 2D resonances of Wannier-Stark electro-optical effect in yz plane correspond to constructive interference of the two-photon states (bosonic behavior), and two-polar resonances in ±z direction are determined by destructive interference of the two-photon states (fermionic behavior). Two-polar oscillations of 1D -polaritons have the ultra-small half-width 0.4–0.6 сm–1 and minimal Rabi frequency of samples 1.0 сm–1 equaled to the resolution of spectral measurements. Furthermore, two-photon interference and 1D polaritons are perspective for high-coherent optical quantum computers on macroporous silicon with nano-coatings and, in addition, for lasers and new metamaterials.

Electrochemical synthesis and characterization of CuO/ZnO/SnO nano photocatalyst: Evaluation of its application towards photocatalysis, photo-voltaic and antibacterial properties

The electrochemical procedure has been employed to synthesize CuO/ZnO/SnO nanoparticles using NaHCO 3 as the conductive salt under ambient conditions. The synthesized nanoparticles showed an average crystallite size of 33.7 nm with an orthorhombic structure. The X-ray diffraction, scanning electron microscope, energy dispersive X-ray analysis, IR and optical absorption spectroscopy have been employed for size, morphology, chemical composition, and optical properties characterization. The bandgap obtained from Tauc's plot was found to be 2.6 eV. The photocatalytic activity was evaluated by the photodegradation of methylene blue dye under sunlight which follows first-order kinetics. The higher efficiency of photodegradation was achieved at a mere low concentration of 0.02 g of the nano photocatalyst. The antibacterial activity was tested on human pathogens Bacillus subtilis (MTCC 121) , Pseudomonas aeruginosa (MTCC 183), Salmonella typhi (MTCC 733) by disc diffusion method.