Exciton optical absorption coefficients and refractive index changes in a strained InAs/GaAs quantum wire: The effect of the magnetic field

Magnetic field induced exciton binding energy is investigated in a strained InAs/GaAs quantum wire within the framework of single band effective mass approximation. The strain contribution to the potential is determined through deformation potentials. The interband emission energy of strained InAs/GaAs wire is investigated in the influence of magnetic field with the various structural parameters. Magnetic field induced photoionization cross section of the exciton is studied. The total optical absorption and the refractive index changes as a function of normalized photon energy between the ground and the first excited state in the presence of magnetic field are analyzed. The optical absorption coefficients and the refractive index changes strongly depend on the incident optical intensity and the magnetic field. The occurred blueshift of the resonant peak due to the magnetic field will give the information about the variation of two energy levels in the quantum well wire. The optical absorption coefficients and the refractive index changes are strongly dependent on the incident optical intensity and the magnetic field.     

Scaled Quantum Chemical Studies of the Molecular Structure and Vibrational Spectra of Minoxidil

The Fourier transform Raman and Fourier transform infrared spectra for minoxidil have been recorded in the region 4000—100 cm^?1 and 4000—450 cm^?1, respectively. The structural and spectroscopy data of the molecule in the ground state were calculated by using density functional theory methods with 6-311G (d, p) basis set. A detailed vibrational analysis of the title compound has been done using normal coordinate analysis following the scaled quantum mechanical force field methodology. The calculated molecular geometry parameters and scaled vibrational wavenumbers are well compared with the experimental data. The electronic properties, such as excitation energies, absorption wavelength, highest occupied molecular orbital (HOMO), and lowest unoccupied molecular orbital (LUMO) energies were performed by time-dependent density functional theory approach, and the results are in good agreement with experimental absorption spectrum. The charge delocalizations of these molecules have been analyzed using natural bond orbital analysis. The molecule orbital contributions are studied by density of energy states. Fukui functions, local softness, and electrophilicity indices for selected atomic sites of the title compound are determined. Finally, the thermal behaviors of the compound have been calculated by different temperature.     

Encapsulation of [F4(H2O)10](4-) in a dimeric assembly of an unidirectional arene based hexapodal amide receptor

An unidirectional orientation of all six arms of an arene based hexapodal amide receptor shows dimeric capsular assembly templated by a [F(4)(H(2)O)(10)](4-) cluster.     

Preconcentration and speciation of inorganic and methyl mercury in waters using polyaniline and gold trap-CVAAS

Applicability of polyaniline (PANI) has been investigated for the preconcentration and speciation of inorganic mercury (Hg²⁺) and methyl mercury (CH₃Hg⁺) in various waters (ground, lake and sea waters). Preliminary experiments (batch) with powdered PANI for the quantitative removal of both Hg²⁺ and CH₃Hg⁺ showed that the retention of Hg²⁺ was almost independent of pH while a pH dependent trend from pH 1 to 12 was seen for CH₃Hg⁺ with maximum retention at pH > 5. Time dependence batch studies showed that a contact time of 10 min was sufficient to reach equilibrium. The K_d values were found to be ∼8 × 10⁴ and ∼7 × 10³ for Hg²⁺ and CH₃Hg⁺, respectively.Subsequently column experiments were carried out with PANI and the separation of the species was carried out by selective and sequential elution with 0.3% HCl for CH₃Hg⁺ and 0.3% HCl-0.02% thiourea for Hg²⁺. This was then followed by further pre-concentration of mercury on a gold trap and its determination by CVAAS. The uptake efficiency studies showed that the PANI column was able to accumulate up to 100 mg Hg²⁺/g and 2.5 mg CH₃Hg⁺/g. This method allows both preconcentration and speciation of mercury with preconcentration factors around 120 and 60 for Hg²⁺ and CH₃Hg⁺, respectively. The interfering effects of various foreign substances on the retention of mercury were investigated.     

Atomically Precise Defective Copper Nanocluster Catalysts for Highly Selective C−C Cross-Coupling Reactions

Point defects in nanoparticles have long been hypothesized to play an important role in governing the particle's electronic structure and physicochemical properties. However, single point defects in material systems usually exist with other heterogeneities, obscuring the chemical role of the effects. Herein, we report the synthesis of novel atomically precise, copper hydride nanoclusters (NCs), [Cu₂₈H₁₀(C₇H₇S)₁₈(TPP)₃] ( Cu₂₈ ; TPP: triphenylphosphine; C₇H₇S: o-thiocresol) with a defined defect in the gram scale via a one-pot reduction method. The Cu₂₈ acts as a highly selective catalyst for C−C cross-couplings. The work highlights the potential of defective NCs as model systems for investigating individual defects, correlating defects with physiochemical properties, and rationally designing new nanoparticle catalysts.     

Water-Mediated Strecker Reaction: An Efficient and Environmentally Friendly Approach for the Synthesis of α-Aminonitriles via a Three-Component Condensation

The synthesis of α-aminonitriles by a direct three component Strecker reaction has been achieved in water, which is found to be an inexpensive, non-toxic and eco-friendly reaction medium for the nucleophilic addition. This protocol is effective to a wide variety of substrates with different functional groups and does not require the use any other catalyst.