Narrow Results

The decay pattern of the low lying levels in the shape transitional nucleus ¹⁵⁰Sm is analyzed in terms of the quasi-vibrational and quasi-rotational collective model. The Dynamic Pairing plus quadrupole Model in the microscopic theory of the collective model is employed to predict extensive structure characteristics. The potential energy surface (PES), the spectroscopic factors and the E2, E0 transition rates from the DPPQ model are illustrated. Comparison is made with the predictions in the Interacting Boson Model (IBM-1). A correspondence is demonstrated of the effect of the control parameter in the two models on the calculated nuclear structure. The study of the wave functions of the two spin I = 2 excited states in IBM is carried out. The alternative view of an anharmonic vibrator and a soft rotor is discussed in terms of the E2 transition rates and other structural characteristics.

The complex singlet and triplet potential energy surfaces (PESs) of the [C₂N₂O₂] system are performed at the B3LYP and Gaussian-3//B3LYP levels in order to investigate the possibility of the carbyne radical CCN in removal of nitrogen dioxide. Thirty minimum isomers and 36 transition states are located. Starting from the very energy-rich reactant RCCN + NO₂, the terminal C-attack adduct NCCN(O)O (singlet at -48.6 and triplet at -48.1 kcal/mol) is first formed on both singlet and triplet PESs. Subsequently, the singlet NCCN(O)O takes an O-transfer to form the intermediate singlet cis-NCC(O)NO (-120.1), which can lead to the fragments NCCO + NO (-94.4) without barrier. The simpler evolution of the triplet NCCN(O)O is the direct N–O rupture to form the final fragmentation NCCNO + ³O (-31.0). However, the lower lying products ³NCNO + CO (-103.3) and NCNCO + ³O (-86.5) are kinetically much less competitive. All the involved transition states for the generation of NCCO + NO and NCCNO + ³O lie much lower than the reactants, and it indicates that this reaction can proceed effectively even at low temperatures. We expect that the reaction CCN + NO₂ can play a role in both combustion and interstellar processes. Comparison is made between the CCN + NO₂ and CH + NO₂ reaction mechanisms.

Quasiclassical trajectory (QCT) calculations have been performed to investigate the reaction dynamics of the title reactions at a state-to-state level. The recently developed adiabatic potential energy surfaces (PESs) of the two triplet electronic states of 1³A″ and 1³A′ (Gómez-Carrasco S. et al., J Chem Phys121:4605, 2004; J Chem Phys123:114310, 2005) are employed in the present QCT calculations. Product vibrational and rotational state distributions have been calculated at three collision energies of 0.5, 0.7 and 0.9 eV. The product vibrational state distributions are found to be Gaussian distributions. Both the vibrational and rotational state distributions depend clearly on the isotope substitution, electronic PESs and collision energies. The observed phenomena are probably attributed to the competition of direct and indirect reactions.

The vector correlations between products and reagents of the N(²D) + D₂ reaction are investigated by employing quasi-classical trajectory (QCT) calculation on the accurate DMBE potential energy surface (PES) of the ²A″ state. Stereo-dynamic quantities, including the four generalized polarization-dependent differential cross-sections (PDDCSs), the angular distribution P(θ_r), the dihedral-angle distribution P(φ_r), as well as the product rotational angular distribution in the polar form of P(θ_r, φ_r), are calculated in the center-of-mass (CM) frame. The results indicate that the product rotational angular momentum j′ not only aligns along the y-axis, but also orients to the negative direction of the y-axis. The isotope effect in the context of chemical stereo-dynamics and influences of different versions of ground-state PESs on vector correlations are shown and discussed.

A new London–Eyring–Polanyi–Sato (LEPS) potential energy surface (PES) is employed in this work to study the stereo properties for the abstraction reaction of hydrogen with methane at its rovibrationally ground state using the quasiclassical trajectory method (QCT). A "quasi-triatomic" approximation is used to treat the CD₃ group of CD₄ as a pseudoatom. The calculated excitation function of the title reaction can give a good agreement to most experimental and theoretical data at collision energies (E_c =1.5 ~ 2.5 eV). Further investigation of the product HD in reaction H + CD₄(v = 0, j = 0) → HD + CD₃ and D + CH₄(v = 0, j = 0) → HD + CH₃ shows the dependence of the product rotational polarization on collision energies and mass factor, but P(θ_r) is not sensitive to both the collision energies and the mass factor.

The effect of external perturbations, namely solvent and external electric field on potential energy surface (PES) and bond dissociation energy of C–X (X$=$F, Cl, Br, N, O) bonds has been studied in the light of density functional theory (DFT). The study reveals that presence of solvent as well as external electric field changes the curvature of the PES significantly. Bond dissociation energy significantly drops in presence of both the external perturbation.

A dual-level quantum chemical calculations have been carried out on the initiation of night-time degradation of 2-chloroethyl ethyl ether (CH₃CH₂OCH₂CH₂Cl) via H-abstraction by NO₃ radical. Within the scope of density functional theory, the electronic structure of all the species involved in the titled reaction has been optimized at M06-2X functional along with 6-31$+$G(d,p) basis set. A higher level of couple cluster CCSD(T) method in conjunction with 6-311$++$G(d,p) basis set has been used for the refined energy of the species. All minima and saddle states involved in the reaction channel have been characterized on the potential energy surface (PES). From PES, it is confirmed that H-abstraction from methylene (–CH₂–) of ethyl (CH₃CH₂–) part of CH₃CH₂OCH₂CH₂Cl follows the minimum energy path. The rate constants (individual and overall) of the titled reaction are obtained using Canonical Transition State Theory (CTST) over the temperature range of 250–350K. The atmospheric lifetime and radiative efficiency of the titled molecule have also been estimated, amounting to 0.23 years and 0.024 years, respectively. The Global Warming Potentials of the 2-chloroethyl ethyl ether in 20 years, 100 years and 500 years time horizon were found to be 0.13, 0.04 and 0.01, respectively.

Ultrafiltration membranes were prepared using phenolphthalein polyarylethersulfone (PES-C), polyethersulfone (PES) and poly(phthalazinone ether sulfone ketone) (PPESK) as polymers and NMP, DMAc, DMF and DMSO as solvents by immersion precipitation via phase inversion. Experimental data of thermodynamic properties of the polymer solutions and kinetic process of membrane formation were reported. For polymer solutions with good solvents, the sequence of the viscous flow activation energy (E_η) was coincident with that of the viscosity (η), without depending on the dissolving power of the solvents (characterized by intrinsic viscosity ([η])). The cloud point of the dilute polymer solutions was related to [η] of the polymer and gave a strong influence on the gelation rate in membrane formation process. The pure water flux (J) and the bovine serum albumin (BSA) rejection (R) of PES-C, PES and PPESK membranes were measured, the pure water flux (J) of membranes significantly depended on the gelation rate. The open porosity (OP) and the maximum pore size of membrane surface were calculated, and the relationship between membrane performance and membrane pore structure was discussed.

SINS is a soft X-ray spectroscopy facility at SSLS, dedicated to Surface, Interface and Nanostructure Science of advanced materials. Developed over the past few years, the SINS end-station includes a photoemission spectroscopy analyzer, LEED, in situ STM/AFM, and a separate sample preparation chamber. Applications to such fields as molecular electronics, high density data storage, and nanonetwork templates are briefly reviewed.

Valuing water is difficult and contentious owing to water’s physical, political, and economic characteristics. Combining household-level and county-level data at the county level could clarify the responsibilities of both the government and users. In the Thousand Island Lake Water Distribution Project (TILWDP), the upstream ecosystem services provider, Chunan County, is assumed to sustain a tremendous opportunity cost due to the extremely strict environmental protection requirements of the project. To estimate the opportunity cost of supplying fresh water that meets the standards of the National Primary Drinking Water Regulations, a synthetic control model is introduced, and county-level macroeconomic data are used. A funding gap was estimated in the current government-financed situation. Meanwhile, willingness to pay is calculated based on household-level data collected in the downstream area. The estimate indicates that the combination of ecological compensation payments from governments and downstream stakeholders’ willingness to pay for water services could completely cover the upstream service provider’s opportunity cost. Specifically, the related central and downstream governments would need to take on approximately 1/3 of the total cost, while the users from the downstream area would take on the rest. The proposed policies include adopting government–user joint-financing payment for ecosystem services (PES) schemes for regional ecological and environmental cooperation in China, implementing diversified payment vehicles, launching additional environmental education projects, etc.

The flavonoid derivatives of 4′-dimethylaminoflavonol (DMAF) in acetonitrile solvent and 3,7-dihydroxy-4-oxo-2-phenyl-4H-chromene-8-carbaldehyde (2a) in methylcyclohexane solvent have been investigated on the excited-state intramolecular proton transfer (ESIPT) based on the time-dependent density functional theory (TDDFT) method. The calculated absorption and fluorescence spectra agree well with the experimental results. The analyses of bond distance, bond angle, the molecular electrostatic potential surface and the infrared vibrational spectra show that intramolecular hydrogen bonds were formed in the S₀ state, and upon excitation, the intramolecular hydrogen bonds were strengthened in the S₁ state, which can facilitate the proton-transfer (PT) process. The constructed potential-energy curves/surfaces (PES) on the S₁ and S₀ states can be used to demonstrate the PT process. In terms of DMAF with one hydrogen bond, our calculations suggest that intramolecular hydrogen bonds can boost intramolecular PT in the twisted intramolecular charge-transfer (TICT) state. For the flavonoid derivative bearing two hydrogen bonds, i.e., 2a, however, the TICT state has little impact on 2a. Instead, three PT types in the excited state (ES) occur. By analyzing the PES, the preferred pathway was also determined. Our work not only gives a detailed PT process in the ES but also provides theoretical significance for further study of flavonoid derivatives.