醛类分子的拉曼光谱研究

应用便携式拉曼光谱仪,采集了四种醛类分子(GnH2nO,n=1,2,3,4)的拉曼光谱,并通过量子化学中密度泛函理论(DFT)对四种醛类分子进行了分子模型构建和理论拉曼光谱模拟计算.通过实验拉曼光谱和DFT模拟计算结果的对比,对四种醛类分子的特征振动峰进行了指认.同时对四种醛类分子的实验光谱进行了分析比较.应用便携式拉...     

Constraining spacetime torsion with LAGEOS

We compute the corrections to the orbital Lense-Thirring effect (or frame-dragging) in the presence of spacetime torsion. We analyze the motion of a test body in the gravitational field of a rotating axisymmetric massive body, using the parametrized framework of Mao, Tegmark, Guth and Cabi. In the cases of autoparallel and extremal trajectories, we derive the specific approximate expression of the corresponding system of ordinary differential equations, which are then solved with methods of Celestial Mechanics. We calculate the secular variations of the longitudes of the node and of the pericenter. We also show how the LAser GEOdynamics Satellites (LAGEOS) can be used to constrain torsion parameters. We report the experimental constraints obtained using both the nodes and perigee measurements of the orbital Lense-Thirring effect. This makes LAGEOS and Gravity Probe B complementary frame-dragging and torsion experiments, since they constrain three different combinations of torsion parameters.     

Quantum scalar field in quantum gravity: the propagator and Lorentz invariance in the spherically symmetric case

We recently studied gravity coupled to a scalar field in spherical symmetry using loop quantum gravity techniques. Since there are local degrees of freedom one faces the “problem of dynamics”. We attack it using the “uniform discretization technique”. We find the quantum state that minimizes the value of the master constraint for the case of weak fields and curvatures. The state has the form of a direct product of Gaussians for the gravitational variables times a modified Fock state for the scalar field. In this paper we do three things. First, we verify that the previous state also yields a small value of the master constraint when one polymerizes the scalar field in addition to the gravitational variables. We then study the propagators for the polymerized scalar field in flat space-time using the previously considered ground state in the low energy limit. We discuss the issue of the Lorentz invariance of the whole approach. We note that if one uses real clocks to describe the system, Lorentz invariance violations are small. We discuss the implications of these results in the light of Hořava’s Gravity at the Lifshitz point and of the argument about potential large Lorentz violations in interacting field theories of Collins et al.     

Rapid Convergence to Frequency for Substitution Tilings of the Plane

This paper concerns self-similar tilings of the Euclidean plane. We consider the number of occurrences of a given tile in any domain bounded by a Jordan curve. For a large class of self-similar tilings, including many well-known examples, we give estimates of the oscillation of this number of occurrences around its average frequency times the total number of tiles in the domain, which depend only on the Jordan curve.     

Testing Super-Deterministic Hidden Variables Theories

We propose to experimentally test non-deterministic time evolution in quantum mechanics by consecutive measurements of non-commuting observables on the same prepared state. While in the standard theory the measurement outcomes are uncorrelated, in a super-deterministic hidden variables theory the measurements would be correlated. We estimate that for macroscopic experiments the correlation time is too short to have been noticed yet, but that it may be possible with a suitably designed microscopic experiment to reach a parameter range where one would expect a super-deterministic modification of quantum mechanics to become relevant.     

High-speed scanning fiber-optic heterodyne interferometer using a micro-electro-mechanical system mirror and an f-theta lens

This paper describes a novel fiber-coupled heterodyne interferometer using a micro-electro-mechanical system (MEMS) mirror and an f-theta lens. In this interferometer system, the cross-polarized laser beams operating at 2 μm with the frequency difference of 100 kHz are introduced by means of the two acousto-optic modulators (AOM). The sample with diameter of 300 mm is uniformly scanned by the 1 mm laser beam with the help of the combined optical scanning configuration, a MEMS mirror and an f-theta lens. The output intermediate signal from the two channels, reference channel and the measurement channel, are processed in the 12 bit analog-to-digital (A/D) process system. Details of our interferometer scheme are discussed.     

Evaporative Preconcentration of Fluorescent Protein Samples in Capillary Based Microplates

The preconcentration of analytes is important in biochemical analysis as it offers the ability to detect for trace species, and increase signal-to-noise ratios when using optical sensing on fluorophores. A strong advantage of the evaporation technique lies in its ability to operate without the need of any energy source; albeit major challenges exist on how to increase the surface area exposure to air for heightened evaporation, ensure no further increases once specified analyte concentrations have been achieved, and not needing any intervening membranes. We demonstrate here that the droplet creation and retraction approach in capillary based microplates offers such abilities whilst at the same time facilitating mixing.     

<Emphasis Type="Italic">ρρ</Emphasis>N and <Emphasis Type="Italic">ρρ</Emphasis>Δ molecules with J<Superscript>P</Superscript> = 5/2<Superscript>+</Superscript> and J<Superscript>P</Superscript> = 7/2<Superscript>+</Superscript>

The ρρN and ρρΔ three-body systems have been studied within the framework of the fixed center approximation of Faddeev equation. The ρρ interaction in isospin I = 0 , spin S = 2 is strongly attractive, and so are the N ρ, ρΔ interactions. This leads to bound states of both ρρN and ρρΔ. We find peaks of the modulus squared of the scattering matrix around 2227 MeV for ρρN, and 2372 MeV for ρρΔ. Yet, the strength of the peak for the ρρN amplitude is much smaller than for ρρΔ, weakening the case for a ρρN bound state, or a dominant ρρN component. A discussion is made on how these states can be searched for in present programs looking for multimeson final states in different reactions.     

Large-scale synthesis of Ag<Subscript>1.8</Subscript>Mn<Subscript>8</Subscript>O<Subscript>16</Subscript> nanorods and their electrochemical lithium-storage properties

Ag_1.8Mn₈O₁₆ nanorods have been synthesized on a large scale by a facile hydrothermal route. The effects of experimental conditions including reaction time and reactant concentration on the phase and morphology of the final products were investigated systematically. The products were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX) spectroscopy. Electrochemical lithium-storage capabilities of the as-formed nanostructured Ag_1.8Mn₈O₁₆ were also evaluated. Interestingly, the as-formed Ag_1.8Mn₈O₁₆ nanorods possess the unique one-dimensional structure and in situ silver loading, which are beneficial features for electrochemical lithium-storage applications. The results suggest their potential use as cathode materials for lithium-ion batteries.