R-matrix methods for studying nuclear effects in μCF

Properties ofR-matrix theory that are useful for studying muon-catalyzed fusion reactions are reviewed, and applications to the dt system are discussed, using both improved adiabatic and non-adiabatic (variational) wave functions. We give complex eigenvalues and - sticking fractions for the (L, v)=(0,0) and (0, 1) states of dt using variational Hamiltonian matrix elements that have been properly symmetrized by means of the Block operator. Expressions for the fusion rate and - sticking fraction are developed from a time-dependent theory that uses the complex-energy states corresponding to the poles of the systemS-matrix. These are shown to reduce with the appropriate approximations to the expressions and values commonly used. Additional nuclear effects on these quantities can easily be studied within the framework developed, but they are not expected to be large.     

Conformational analysis—II: A lanthanide-induced shift nmr and theoretical study of bicyclo [3.1.0] hexan-3-one and adamantanone

The solution conformation of bicyclo [3.1.0] hexan-3-one has been obtained by the use of the shifts induced in its ¹H and ¹³C NMR by Yb(fod)₃. Refinement of the angle of pucker, ∝, of the 5-membered ring indicates that the molecule adopts a flattened boat conformation with ∝ = 195°. This prediction is supported by ab initio, STO-3G, calculations on the isolated molecule. Use of a two- or four-site model for lanthanide-substrate complexing adequately reproduces the experimental data whereas a one-site binding model is unsatisfactory. The importance of multi-site binding is further emphasised by results for the C_2v-symmetric ketone, adamantanone, where only a four-site model gives satisfactory agreement between observed and calculated lanthanide-induced shifts.     

Xe对NO(X)微分截面和非弹性散射中的碰撞诱导旋转准直

本文对NO(X)-Xe碰撞系统在碰撞能量为519 cm^-1,测量了完全?-双峰分解的微分截面和碰撞引起的旋转准直力矩. 同时结合初始量子态选择,使用六极杆的非均质电场,借助量子态分辨的测量,利用(1+1'')共振增强的多光子电离和速度离子成像. 结果显示,微分截面以及偏振相关的微分截面均显示与从头算势能面上进行的量子力学散射计算[J. K?os etal. J. Chem. Phys. 137, 014312 (2012)]一致. 通过与准经典轨迹、硬壳势能的量子力学散射以及运动近端模型的比较,评估了势能对所测微分截面和碰撞引起的旋转准直力矩的影响.     

The Stabilization of Metal Oxide Nanocrystals by the Addition of Alumina

A problem in the study of nanoparticles is that they will tend to grow at moderate temperatures. For example, most oxides (e.g. SnO₂, ZrO₂, MgO) will show significant grain growth at 400°C. This severely limits experimental studies that require measurements over an extensive temperature range. In this contribution we demonstrate that the incorporation of A1₂O₃, can significantly restrict grain growth in MgO and ZrO₂ even at high temperatures.     

Visualization of flameholding mechanisms in a supersonic combustor using PLIF

Laser-induced fluorescence of OH and CH₂O was imaged to investigate the flame stabilization mechanism in a flameholder with a Mach 2.4 free stream. Ethylene was burned in a rectangular cavity with two points of injection: the aft wall and the cavity floor. When injected from the aft wall, the fuel came into immediate contact with hot combustion products from the reaction zone under the shear layer. Primary combustion occurred under the shear layer and in the aft region of the cavity volume. In contrast, when fuel was injected from the floor, a jet-driven recirculation zone of hot products near the upstream wall of the cavity served as a flameholder. The reaction then occurred on the underside of the shear layer. In conditions near lean blowout, significant changes in the flameholding mechanisms were observed. Improved CH₂O fluorescence signal was obtained by taking advantage of the long fluorescence lifetime at low pressures and delaying the camera gate to reduce the background signal.