Liquid Benzene Research Articles

Deep ultraviolet Raman spectroscopy: A resonance-absorption trade-off illustrated by diluted liquid benzene

The magnitude of resonance Raman intensity, in terms of the real signal level measured on-resonance compared to the signal level measured off-resonance for the same sample, is investigated using a tunable laser source. Resonance Raman enhancements, occurring as the excitation energy is tuned through ultraviolet absorption lines, are used to examine the 1332 cm−1 vibrational mode of diamond and the 992 cm−1 ring-breathing mode of benzene. Competition between the wavelength dependent optical absorption and the magnitude of the resonance enhancement is studied using measured signal levels as a function of wavelength. Two system applications are identified where the resonance Raman significantly increases the real signal levels despite the presence of strong absorption: characterization of trace species in laser remote sensing and spectroscopy of the few molecules in the tiny working volumes of near-field optical microscopy.

Molecular dynamics simulation of benzene

Intermolecular potentials and a few models of intermolecular interaction in liquid benzene are tested by Molecular Dynamics (MD) simulations. The repulsive part of the Lennard-Jones 12-6 (LJ 12-6) potential is too hard, which yields incorrect results. The exp-6 potential with a too hard repulsive term is also often used. Therefore, we took an expa-6 potential with a small Gaussian correction plus electrostatic interactions. This allows to modify the curvature of the potential. The MD simulations are carried out in the temperature range 280–352 K under normal pressure and at experimental density. The Rayleigh scattering of depolarized light is used for comparison. The results of MD simulations are comparable with the experimental values.

Atmospheric Pressure Chemical Vapor Deposition of Graphene Using a Liquid Benzene Precursor.

Graphene has attracted great attention owing to its unique structural and electrical properties. Among various synthetic approaches of the graphene, metal assisted chemical vapor deposition (CVD) is the most reasonable and proper method to produce large-scale and low-defect graphene films. Until now, CVD from gaseous hydrocarbon sources has shown great promises for large-scale graphene growth, but high growth temperature is required for such growth. A recent work by using liquid benzene precursor has shown that monolayer graphene could be obtained at 300 degrees C by low pressure, required for high vacuum equipment. Here, we report the first successful attempt of atmospheric pressure CVD graphene growth on Cu foil using liquid benzene as a precursor. We investigated the effect of hydrogen partial pressure, growth time, and precursor temperature on the domain size of as-grown graphene. Also, micro-Raman analysis confirmed that these reaction parameters influenced the number of layer and uniformity of the graphene.

Physico-Chemical Behaviour of Benzophenone with Benzene At 303.15 K Using Ultrasonic Measurements

Ultrasonic investigations throw a light on the molecular interactions between solute and solvent molecules. The ultrasonic velocities, densities and viscosities have been measured for the binary liquid mixtures benzophenone and benzene of different mole fractions at 303.15 K. The obtained experimental data are used to calculate the acoustical parameters like adiabatic compressibility (β), free length (Lf), free volume (Vf), internal pressure (πi), interaction parameter (χ) and acoustic impedance (Z). The deviations in the parameters suggest the structure breaking tendency of the solvent molecules.

Solvent extraction and separation of light lanthanoids with mixtures of two chelating extractants: Benzene vs. ionic liquid

ABSTRACTSolvent extraction of lanthanoids (La-Gd) with mixtures of a chelating extractants (HL), either 4-(4-fluorobenzoyl)-3-methyl-1-phenyl-pyrazol-5-one(HPMFBP) or 3-methyl-4-(4-methylbenzoyl)-1-phenyl-pyrazol-5-one (HPMMBP) and 1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedione (thenoyltrifluoroacetone, HTTA) has been studied in benzene. The composition of the extracted species was established as LnL3·HL with the two para-substituted 4-aroyl-3-methyl-1-phenyl-pyrazol-5-ones. It was found that, in the presence of a thenoyltrifluoroacetone, the lanthanoids were extracted as LnL3·HTTA. The separation factors between adjacent metals were evaluated. The extraction of Eu(III) ions was investigated by use of ionic liquid, 1-methyl-1,3-butylimidazolium-bis(trifluoromethanesulfonyl)imide instead of benzene in order to make comparison without looking at the mechanism aspects.

Low-temperature heat capacities of confined liquid benzene, implying the behavior of ordinary bulk liquids

Isobaric heat capacities Cp of benzene confined in silica MCM-41 mesopores with average diameters equal to and smaller than 2.9 nm were measured by precise adiabatic calorimetry. The confined benzene samples revealed no thermal anomaly due to crystallization/fusion and vitrified at low temperatures. The Cp curves displayed a hump and a considerably quick decrease on the low-temperature side of the hump as the pore diameter increased. The enthalpy-relaxation effects observed on intermittent heating showed that the anomaly of the Cp hump and quick decrease is not assigned to a glass transition. The bend in the temperature dependence of density reported previously was interpreted as corresponding to the quick decrease in Cp. We concluded that the anomalous Cp and density behaviors originated from the ordering/excitation in the configurational state, close to the ground state, of confined molecular aggregate and proposed a scenario that explains the general Cp curves of ordinary bulk supercooled liquids in equilibrium at low temperatures below the glass-transition temperatures.

Fabrication of large size graphene and Ti- MWCNTs/ large size graphene composites: their photocatalytic properties and potential application.

Large size graphene (LSG) and multiwall carbon nanotubes (MWCNTs) on LSG were synthesized on a copper surface via chemical vapor deposition (CVD) at low temperature and normal pressure. The LSG were formed through an easy chemical cyclic reaction in which liquid benzene was heated to a temperature below its boiling point to create benzene vapors as graphene precursor material. The reaction mechanism was observed, and the time-dependent analysis of the reaction revealed that mounds of the carbon nanotubes had grown as a result of the island that was found on the LSG sheet. The implications of the mechanism that we have introduced were investigated by coating a titanium sheet on the MWCNTs/LSG and LSG on the semiconductor electronic device. The photonic response was observed to be markedly high, which can be attributed to the positive synergetic effect between the Ti and LSG sheet of our prepared composites.

Local Field Factors and Dielectric Properties of Liquid Benzene.

Local electric field factors are calculated for liquid benzene by combining molecular dynamic simulations with a subsequent force-field model based on a combined charge-transfer and point-dipole interaction model for the local field factor. The local field factor is obtained as a linear response of the local field to an external electric field, and the response is calculated at frequencies through the first absorption maximum. It is found that the largest static local field factor is around 2.4, while it is around 6.4 at the absorption frequency. The linear susceptibility, the dielectric constant, and the first absorption maximum of liquid benzene are also studied. The electronic contribution to the dielectric constant is around 2.3 at zero frequency, in good agreement with the experimental value around 2.2, while it increases to 6.3 at the absorption frequency. The π → π* excitation energy is around 6.0 eV, as compared to the gas-phase value of around 6.3 eV, while the experimental values are 6.5 and 6.9 eV for the liquid and gas phase, respectively, demonstrating that the gas-to-liquid shift is well-described.

Molar volume calculated at various pressures and the Pippard relations close to the melting point in benzene

ABSTRACTThe molar volume of solid and liquid benzene was calculated at various pressures (at constant temperatures), and the Pippard relations were examined close to the melting point in this organic molecule.The molar volume calculated is in good agreement with the observed data, which decreases as the pressure increases up to about 150 MPa. The Pippard relations are also valid within this pressure range at constant temperatures studied here for the solid and liquid phases of benzene.

The Effect of Vanadium Oxide on The Catalytic Activity of Titanium Silicalite in Conversion of Benzene to Phenol

Phenol is one of the most important intermediate for petrochemical, agrochemical, and plastics industries<em>. </em>Almost<em> 95% phenol is </em>produced using cumene method. Cumene method is a multi-stage process with many disadvantages including the difficulties to gain phenol product in maximum quantities and production of co-product such as acetone which has great amount in market nowadays. One of the alternative routes to produce phenol which has more advantages is through benzene hydroxylation reaction using H<sub>2</sub>O<sub>2</sub> as oxidant agent and Titanium Silikalit-1 (TS-1) as catalyst. TS-1 catalyst has high catalytic activity and selectivity in selective oxidation reaction of aromatic compounds with H2O2 which important for commercial industries. However, the reaction rate is tend to be low because TS-1 has hydrophobic nature and as the result H2O2 adsorption which has hydrophilic nature towards active sites of TS-1 is also become slower. Addition of metal oxide V2O5 could enhance hydrophilicity of TS-1 catalyst. Liquid phase catalytic benzene hydroxylation using hydrogen peroxide as oxidant was carried out over vanadium (V) oxide-modified TS-1 catalyst (V<sub>2</sub>O<sub>5</sub>/TS-1), that were prepared by impregnation method using vanadium methavanadate as precursor and characterized by pyridine adsorption and hydrophilicity techniques.

Accurate Measurements of Dielectric and Optical Functions of Liquid Water and Liquid Benzene in the VUV Region (1-100 eV) Using Small-Angle Inelastic X-ray Scattering.

Using a third-generation synchrotron source (the BL12XU beamline at SPring-8), inelastic X-ray scattering (IXS) spectra of liquid water and liquid benzene were measured at energy losses of 1-100 eV with 0.24 eV resolution for small momentum transfers (q) of 0.23 and 0.32 au with ±0.06 au uncertainty for q. For both liquids, the IXS profiles at these values of q converged well after we corrected for multiple scattering, and these results confirmed the dipole approximation for q ≤ ∼0.3 au. Several dielectric and optical functions [including the optical oscillator strength distribution (OOS), the optical energy-loss function (OLF), the complex dielectric function, the complex index of refraction, and the reflectance] in the vacuum ultraviolet region were derived and tabulated from these small-angle (small q) IXS spectra. These new data were compared with previously obtained results, and this comparison demonstrated the strong reproducibility and accuracy of IXS spectroscopy. For both water and benzene, there was a notable similarity between the OOSs of the liquids and amorphous solids, and there was no evidence of plasmon excitation in the OLF. The static structure factor [S(q)] for q ≤ ∼0.3 au was also deduced and suggests that molecular models that include electron correlation effects can serve as a good approximation for the liquid S(q) values over the full range of q.

Identification of atomic lines and molecular bands of benzene and carbon disulfide liquids by using LIBS

Plasma emission of liquid benzene (C6H6) and carbon disulfide (CS2) have been studied by using the laser-induced breakdown spectroscopy (LIBS) technique in air. Atomic lines of carbon, hydrogen, sulfur, nitrogen, and oxygen and molecular emissions of CN and C2 have been identified. The formation mechanism of C2 and CN molecules has been discussed. The combustion process and high mole fraction of hydrogen in benzene caused a decreasing atomic line intensity of oxygen and an increasing atomic line intensity of hydrogen with respect to the CS2 and air. Additionally, more intense CN molecular bands and weak nitrogen atomic lines in the C6H6 spectrum compared to CS2 have been observed. Furthermore, molecular emissions of C2 have not been observed in the CS2 spectrum. The electron temperature and vibrational temperature have been calculated from the atomic lines and molecular band intensity, respectively. Finally, the validity of the local thermodynamic equilibrium (LTE) assumption in this experiment has been shown.

Light-Induced Mid-Infrared Emission of Liquid Carbon Tetrachloride and Benzene

Light-induced infrared emission spectroscopy (LIRES) is a novel technique that permits to receive high-quality spectra in the mid-infrared region. Low-intensity visible light connected to a highly sensitive FTIR spectrometer is more advantageous for studying any samples, including biological samples without any damage. This technique permits obtaining unique information on the molecule structure via vibrational excitation fundamental frequencies, overtones, and combination modes. It also enables a direct observation of vibrational radiation transitions in vibrationally excited molecules as well as the channels of vibration energy redistribution, which is not allowed with any other method. In this work, the LIRES is being tested as a technique for studying of vibrationally-excited molecules of carbon tetrachloride and benzene in the liquid phase. On the other hand, using transparent liquids, we had tried to understand some of the physical phenomena that can drive emission in mid-IR. The characteristics of the infrared emission of both liquid species produced by different wavelength radiation from various types of light systems (100 - watt Xe-lamp and Nd:YAG laser; lambda = 1064 nm (8 mW) and lambda = 532 nm (4 mW)) are presented. We demonstrated that the IR-signal, as well as spectral properties of carbon tetrachloride and benzene, was dependent on the wavelength and power of excitation beam. Results obtained with different light sources show that the visible light produces a nonlinear IR-emission signal in transparent liquids. We believe that the visible light is the source of the nonlinear response and is producing the vibration excitation as well as photostimulated transformations of the molecules possessing the high activity for the nonlinear response.

Assessing Polarizability Models for the Simulation of Low-Frequency Raman Spectra of Benzene.

Optical Kerr effect (OKE) spectroscopy is a widely used technique for probing the low-frequency, Raman-active dynamics of liquids. Although molecular simulations are an attractive tool for assigning liquid degrees of freedom to OKE spectra, the accurate modeling of the OKE and the motions that contribute to it relies on the use of a realistic and computationally tractable molecular polarizability model. Here we explore how the OKE spectrum of liquid benzene, and the underlying dynamics that determines its shape, are affected by the polarizability model employed. We test a molecular polarizability model that uses a point anisotropic molecular polarizability and three other models that distribute the polarizability over the molecule. The simplest and most computationally efficient distributed polarizability model tested is found to be sufficient for the accurate simulation of the many-body polarizability dynamics of this liquid. We further find that the atomic-to-molecular polarizability transformation approximation [Hu et al. J. Phys. Chem. B 2008, 112, 7837-7849], used in conjunction with this distributed polarizability model, yields OKE spectra whose shapes differ negligibly from those calculated without this approximation, providing a substantial increase in computational efficiency.

UTILITY OF HADKAR FACTOR IN THE DETERMINATION OF CRITICAL MICELLE CONCENTRATION OF SURFACTANTS

The drop weight method was used to determine the interfacial tension between organic liquid and solutions of different concentrations of the surfactant, sodium lauryl sulphate (SLS), using Hadkar factor. Two experiments were performed to determine the interfacial tension. In the first experiment the drop weight method was used to determine the interfacial tension between water or aqueous surfactant solutions and benzene (liquid lighter than water) using Hadkar factor H1. In the second experiment the drop weight method was used to determine the interfacial tension between water or surfactant solutions and carbon tetrachloride (liquid heavier than water) using Hadkar factor H2. The plot of interfacial tension between benzene or CCl4 and SLS solutions versus concentration of surfactant solution was used to determine the critical micelle concentration (CMC) of the surfactant. The results were in good agreement with the reported values of CMC for SLS showing the utility of Hadkar factor in the determination of CMC of surfactants.

Quantum molecular dynamics simulations of liquid benzene using orbital optimization

The structure of liquid benzene is investigated by quantum molecular dynamics simulations. Results using variationally optimized numerical pseudo-atomic orbitals are compared to those of generic optimized orbitals. The accuracy of the first-principle calculations is compared with recent experimental findings. Simulations using minimal basis sets with optimized orbitals are shown to successfully predict the local structure of liquid benzene, while simulations with non-optimized minimal basis sets have significant errors in the structure of the first solvation shell. The use of a minimal optimized basis set considerably speeds up simulations, while preserving much of the accuracy of a larger basis set formed by generic orbitals. The transferability of the optimized orbitals is also explored under different environmental conditions.

Effect of surfactant on phenanthrene metabolic kinetics by Citrobacter sp. SA01

To attain a better understanding of the effects of surfactants on the metabolic kinetics of hydrophobic organic compounds, the biodegradation of phenanthrene by Citrobacter sp. SA01 was investigated in a batch experiment containing Tween 80, sodium dodecyl benzene sulfonate and liquid mineral salt medium. The Monod model was modified to effectively describe the partition, phenanthrene biodegradation and biopolymer production. The results showed that Tween 80 and sodium dodecyl benzene sulfonate (each at 50mg/L) enhanced phenanthrene metabolism and poly-β-hydroxybutyrate production as indicated by the increasing amounts of intermediates (by 17.2% to 47.9%), and percentages of poly-β-hydroxybutyrate (by 107.3% and 33.1%) within the cell dry weight when compared to their absence. The modified Monod model was capable of predicting microbial growth, phenanthrene depletion and biopolymer production. Furthermore, the Monod kinetic coefficients were largely determined by the surfactant-enhanced partition, suggesting that partitioning is a critical process in surfactant-enhanced bioremediation of hydrophobic organic compounds.

Measurement and analysis of theAm241(n,γ) cross section with liquid scintillator detectors using time-of-flight spectroscopy at the n_TOF facility at CERN

The ^241 Am(n,γ) cross section has been measured at the n_TOF facility at CERN using deuterated benzene liquid scintillators, commonly known as C_6D_6 detectors, and time-of-flight spectrometry. The results in the resolved resonance range bring new constraints to evaluations below 150 eV, and the energy upper limit was extended from 150 to 320 eV with a total of 172 new resonances not present in current evaluations. The thermal capture cross section was found to be σ_th=678±68 b, which is in good agreement with evaluations and most previous measurements. The capture cross section in the unresolved resonance region was extracted in the remaining energy range up to 150 keV, and found to be larger than current evaluations and previous measurements.

Hand-held unit for liquid-type recognition, based on interdigital capacitor

The implementation of a unit capable to recognize liquids based on an interdigital capacitive sensor (IDC) is presented. The sensor’s structure was fabricated on standard FR-4 PCB board. Its capacitance change relies upon permittivity change of the medium above IDC electrodes, representing dielectric properties of the liquid used. Along with the microcontroller and simple interface circuit, information about the type of the liquid is presented on a 2×16 character display and through RS232 connection on PC. Implemented unit was tested against seven liquids (benzene, phenol, acetone, ethanol, methanol, formaldehyde and distillated water) and a steady state when unit only detected air. Results imply usage of this approach for the fabrication of cost effective, portable devices for on-field sensing applications.

Photophysical and Photochemical Studies of Liquids Below Their Freezing Points

Photophysical and photochemical methods are used to investigate liquids below their melting point. In benzene, immediately below the freezing point the rate of decay of pyrene fluorescence increases dramatically. The k increases to some 220- to 230-fold compared to that of fluid solution. With pyrene, the increased rate of decay is associated with excimer formation and with dimethyl aniline with exiplex formation. Decreasing the temperatures from the freezing point to 77 K initially gives rise to an increase in k which then decreases gradually to 77 K. Spectroscopy shows that in the frozen medium the pyrene environment is that in liquid benzene. The data point to the fact that on freezing all the benzene does not freeze, a small 0.2% remaining fluid. On freezing the pyrene is forced from the bulk crystalline phase to the liquid zones, thus increasing its concentration and rate of excimer formation. Cyclohexane initially shows similar behavior, but further cooling rapidly decreases the rate of fluorescence...