The vapor-phase infrared and Raman spectra of p-difluorobenzene (h4) and (d4)

This new study of the vapor-phase infrared and Raman spectra of p-difluorobenzene (h₄) and (d₄) includes assignments from the high-resolution electronic spectrum, from fluorescence spectra, and one assignment from the two photon electronic spectrum. A new set of frequencies and assignments has been made for the fundamentals of this important intermediate-sized molecule. The most important changes concern the assignments previously made for the lowfrequency a_u mode (ν₈), two members of the b_2u class (ν₁₉ and ν₂₀), and one very important change for the lowest frequency fundamental of the b_3u (out-of-plane) class (ν₃₀), which has been observed directly in the far infrared. The results are all corroborated by the assignments of the perdeuterated analog where changes in previous assignments of Fermi resonance pairs have also been made. Some interesting differences between the Raman spectra of the vapor and the liquid perproto compounds have not been adequately explained in this study.     

Möbius and hückel systems in the SCF and CI approximations

Over the last 15 years since the introduction of Möbius-Hückel theory, a number of varied questions has accumulated. The most interesting of these deals with the question of whether or not the Möbius-Hückel theory is valid in the SCF and SCF-CI approximation. This paper presents a treatmet which shows that the repulsion and exchange contributions are independent of the Möbius vs Hückel nature of the orbital array. Also it is shown that the one-electron terms are symmetry determined and derive from SCF coefficients. An analytical SCF-CI treatment if given. Several further unanswered questions are also considered.     

An unusual reaction of terramycin with methyl iodide

An unusual fragmentation reaction was observed when terramycin is treated with MeI in acetone at room temp. The reaction proceeds with quaternization, loss of trimethylamine, fission of bonds 4a,5 and 12,12a with formation of an aldehydo-lactone derived from rings B, C and D. Additionally some transformations of this lactone are described.     

Electronic and geometric properties of ETS-10: QM/MM studies of cluster models

Hybrid DFT/MM methods have been used to investigate the electronic and geometric properties of the microporous titanosilicate ETS-10. A comparison of finite length and periodic models demonstrates that band gap energies for ETS-10 can be well represented with relatively small cluster models. Optimization of finite clusters leads to different local geometries for bulk and end sites, where the local bulk TiO6 geometry is in good agreement with recent experimental results. Geometry optimizations reveal that any asymmetry within the axial O-Ti-O chain is negligible. The band gap in the optimized model corresponds to a O(2p) --> Tibulk(3d) transition. The results suggest that the three Ti atom, single chain, symmetric, finite cluster is an effective model for the geometric and electronic properties of bulk and end TiO6 groups in ETS-10.     

Event excess in the MiniBooNE search for ¯νμ→¯νe oscillations

The MiniBooNE experiment at Fermilab reports results from a search for ˉν_{μ}→ˉν_{e} oscillations, using a data sample corresponding to 5.66×102? protons on target. An excess of 20.9±14.0 events is observed in the energy range 475相似文献   

Perturbation Solution for One-Dimensional Flow to a Constant-Pressure Boundary in a Stress-Sensitive Reservoir

Transport in Porous Media - Most analyses of fluid flow in porous media are conducted under the assumption that the permeability is constant. In some “stress-sensitive” rock formations,...