Rb掺杂C60单晶的相衍变和电子态

在C₆₀单晶超高真空解理面上制备C₆₀的Rb填隙化合物薄膜.用同步辐射光电子能谱研究了相衍变过程.观察到对应于固溶相、Rb₁C₆₀和Rb₃C₆₀的电子态密度分布.当数纳米厚Rb₃C₆₀薄膜在C₆₀单晶（111）解理面形成后，室温条件下进一步沉积Rb至样品表面不产生fcc到bct或bcc结构相变.C_{60 关键词： 4}C₆₀和Rb₅C₆₀吸附相')" href="#">金属性Rb₄C₆₀和Rb₅C₆₀吸附相 60单晶')" href="#">C₆₀单晶 相衍变 同步辐射光电子能谱     

Atlas of the O-18 Methanol THZ Fourier Spectrum

In this paper, an atlas of the assigned high-resolution Fourier transform spectra in the range 30-133 cm^-l, corresponding far-infrared torsion-rotation band of O-18 methanol in the vibrational ground state, is presented. The estimated accuracy of the lines is ±0004 cm^-l. This will be of great assistance with our assignments of optically-pumped FIR laser emission in CH₃ ¹⁸0H, in providing FIR data for checking the identification of the IR-pump/FIR-laser transition systems through combination loop relations.     

Theoretical study on the vibrational structure of S0 thiophosgene from the origin to dissociation

In this work, using our vibrational variational calculation method and a recently derived refined quartic potential energy surface for S₀ thiophosgene, we have carried out large scale vibrational calculations to analyze the vibrational structure of this electronic state in the whole range of vibrational excitation energies down from the origin and up to the dissociation limit (at ↼20,000 cm^↙1). In the lower excited vibrational range we have achieved satisfactory coincidence of calculated to experimentally measured frequencies, while at the higher vibrational excitations our main objective has been to estimate what part of the available vibrational level density is effectively involved into the vibrational mixing and IVR. The results from our calculations have been compared to the available experimentally obtained dataset (obtained from synchrotron IR, SEP and LIF spectra) as well as to conclusions from the analyses by other authors using local coupling models.     

The role of quantum chemistry in the elucidation of the elementary mechanisms of catalytic processes: from atoms, to surfaces, to enzymes

The recent activity of the laboratory of quantum and computational chemistry of the University of Calabria in the field of catalysis is shortly reviewed. Theoretical determinations of the potential energy profiles for the cyclotrimerization of acetylene catalyzed by bare and supported niobium atom and the reduction mechanism of nitrate to nitrite by nitrate reductase enzyme are presented as examples of studies in which a certain number of investigation methods mostly used in this field, are applied.     

核运动中的某些集体观察量

在低能核结构研究中,电四极跃迁的B(E2,)值和基态带的态与态能量比值R常被用来衡量核的集体运动属性.本文通过标准的位能面计算,系统地探讨了这些量与核形变参数间的关系.指出B(E2,)值主要取决于核的平衡(静态)形变,目前的Nilsson-Strutinsky-BCS方法可以良好地求得从Z=30到锕系区偶-偶核的合理的形变值,而能量比值R则反映的是位能面的整体结构,例如硬度及非谐和性等.     

Preparation and characterization of poly(ether sulfone)/sulfonated poly(ether ether ketone) blend membranes

Polymer blends of sulfonated poly(ether ether ketone) (SPEEK) and poly(ether sulfone) (PES) in N-methyl-2-pyrrolidinone (NMP) were prepared by solution casting. The investigation on water uptake, methanol uptake, permeability and proton conductivity has been conducted. The spin-lattice relaxation time in the rotating frame of PES/SPEEK blend was obtained from the results of cross-polarization magic angle spinning (CP/MAS) solid state ¹³C NMR. SPEEK blended with PES resulted in increasing , indicating the molecular motion of polymer chain was reduced. The glass transition temperature of the PES/SPEEK blend membranes were predicted by the Kwei equation. PES plays an important role in the decreasing water uptake, methanol uptake and methanol permeability while enhancing the thermal stability of the blend membrane, which shows the feasibility for direct methanol fuel cell.     

Effect of substituents on the absorption properties of three pyridylindolizine derivatives: A DFT and TDDFT study

Ground state properties and the UV–Vis absorption spectra of three recently synthesized pyridylindolizine derivatives have been studied by using density functional theory (DFT) and its time-dependent counterpart TDDFT. Performances of the two widely used hybrid functionals, B3LYP and PBE0, and of four different basis sets have been compared. The two functionals yield absorption spectra which have very similar shapes and characteristics but the excitations calculated with PBE0 are obtained at slightly shorter wavelengths. Basis sets affect the appearances of the calculated absorption spectra only little. Independent of the solvent polarity, simulation of the solvent effects by COSMO induces only slight changes into the ground state properties compared to those calculated in the gas-phase and into the absorption spectra.     

Potential energy surface and thermochemistry for the direct gas phase reaction of germane and water

Gas phase reaction between germane GeH₄ and water H₂O was investigated at CCSD(T)/[aug-cc-pVTZ-pp for Ge + Lanl2dz for H and O]//MP2/6-31G(d,p) level. Only the hydrogen elimination channels are monitored. Within the energy range of 100 kcal/mol, we located nine equilibrium and six transition states on the potential energy surface (PES) of the Ge–O–H systems. GeH₄ reacts with H₂O exothermically (by 2.37 kcal/mol) without a barrier to form a non-planar complex GeH₄·H₂O which isomerizes to GeH₃OH·H₂ and H₂GeOH₂·H₂ with a barrier of 44.34 kcal/mol and 53.75 kcal/mol respectively. The first step of hydrogen elimination gives two non-planar species, GeH₃OH and H₂GeOH₂ but germinol GeH₃OH is found to be more stable. Further thermal decomposition reactions of GeH₃OH involving hydrogen elimination have been studied extensively using the same method. The final hydrogen elimination step gives HGeOH which can exist in cis and trans forms. As the trans form is more stable, only the trans form is considered on the potential energy surface (PES) of the reaction. The important thermochemical parameters (∆_rE_tot + ZPE), ∆_rH and ∆_rG for the H₂ elimination pathways are predicted accurately.     

Molecular structure, spectroscopic studies and first-order molecular hyperpolarizabilities of ferulic acid by density functional study

Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of ferulic acid (FA) (4-hydroxy-3-methoxycinnamic acid) were carried out by using density functional (DFT/B3LYP/BLYP) method with 6-31G(d,p) as basis set. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The vibrational spectral data obtained from solid phase FT-IR and FT-Raman spectra are assigned based on the results of the theoretical calculations. The observed spectra are found to be in good agreement with calculated values. The electric dipole moment (μ) and the first hyperpolarizability (β) values of the investigated molecule have been computed using ab initio quantum mechanical calculations. The calculation results also show that the FA molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. A detailed interpretation of the infrared and Raman spectra of FA was also reported. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The calculated HOMO and LUMO energies shows that charge transfer occur within the molecule. The theoretical FT-IR and FT-Raman spectra for the title molecule have been constructed.