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81.
We study the effect of photon scattering from a path of a four-beam atomic interference setup, which is based on a cesium
atomic beam and two subsequent optical Ramsey pulses projecting the atoms onto a multilevel dark state. While in two-beam
interference, any attempt to keep track of an interfering path reduces the fringe contrast, we demonstrate that photon scattering
in a multiple-path arrangement cannot only lead to a decrease, but - under certain conditions - also to an increase of the
interference contrast. The results are confirmed by a density-matrix calculation. We are aware that in all cases the “which-path”
information carried away by the scattered photons leads to a loss of information that is contained in the atomic quantum state.
An approach to quantify this “which-path” information using observed fringe signals is presented; it allows for an appropriate
measure of quantum decoherence in multiple-path interference.
Received: 27 July 2000 / Published online: 6 December 2000 相似文献
82.
S. Zairi C. Martelet N. Jaffrezic-Renault F. Vocanson R. Lamartine R. M’gaïeth H. Maåref M. Gamoudi 《Applied Physics A: Materials Science & Processing》2001,73(5):585-593
This paper shows the possibility of using oxidised porous silicon (PS) as a transducer material for ion-sensor applications.
It aims to study the over-Nernstian behaviour of the porous electrodes towards the concentration of cations in contact. The
dependence of the sensitivity on the porosity of the samples prepared from highly doped substrates has been studied. Maximal
values of over-Nernstian sensitivities around 240 mV/pNa and ∼92 mV/pCu, corresponding to a PS-layer porosity of about 65%,
obtained respectively from p− and p+ silicon substrates, have been registered. Furthermore, the effect of the porous nanostructure morphology has been studied,
by preparing PS samples from weakly doped wafers. The porous-silicon-based sensor behaviour for different PS-layer thicknesses
has also been experimentally investigated. According to these results, a physical model has been proposed to explain the mechanisms
which govern the charge-carrier transfer from one side to the other of the functionalised oxide layer, and leads to the over-Nernstian
adsorption of the cationic species at the electrolyte/SiO2 interface. Afterwards, the Nernst relation has been generalised accordingly, on one hand, to the previous experimental results,
and on the other hand, to the results obtained about the ion-valency and the electrolyte-temperature effects on the sensor
responses.
Received: 15 December 2000 / Accepted: 18 December 2000 / Published online: 23 March 2001 相似文献
83.
84.
Theoretical and Experimental Study of Scattering of a Plane Wave by an Inhomogeneous Plasma Sphere
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Scattering of electromagnetic waves by an inhomogeneous plasma sphere has been studied theoretically and experimentally. The offset angles of electromagnetic waves caused by the plasma sphere have been observed experimentally. The effects of the electromagnetic wave frequency and plasma density on the offset angle are discussed. The plasma density is estimated with the offset angle. 相似文献
85.
Efficient collection of the scattered light from adsorbates on silver in the attenuated total reflection configuration is demonstrated with a so-called Weierstrass prism. The Raman signal from carbon contamination on silver films is enhanced by two orders of magnitude with respect to the simple external backscattering configuration. 相似文献
86.
Czeslaw Rudowicz Zi-Yuan Yang Jian Qin 《Journal of Physics and Chemistry of Solids》2003,64(8):1419-1428
A new module has been developed within the CFA/MSH computer package, which is applicable for d2 and d8 ions at sites of trigonal symmetry type I (C3v,D3,D3d) and type II (C3,C3i), including the ‘imaginary’ CF term. For the first time the spin-spin (SS) and spin-other-orbit (SOO) interactions have also been included in the Hamiltonian. This module enables to study the contributions to the energy levels and the spin Hamiltonian parameters, i.e. zero-field splitting D and g-factors: g∥ and g⊥. The contributions arising from the spin-orbit (SO), SS, and SOO interaction as well as those due to the low symmetry CF effects induced by the distortion angle ?, which describes the difference between C3 and C3v symmetry, can be studied. As an application of the new module, calculations have been carried out for V3+(3d2) ions in α-Al2O3 crystal, taking into account for the first time the SS and SOO interactions, and the low symmetry CF effects. The results show that (i) the contributions from the SS and SOO interactions to the energy levels are larger for free V3+ ions than those for V3+ ions in α-Al2O3 crystal, (ii) both the contributions to the SH parameters and the energy levels arising from the SOO interaction are larger than those arising from the SS interaction, (iii) the contributions due to the low symmetry CF effects induced by the distortion angle ? are in general significant, (iv) D and g⊥ are sensitive to the distortion angle ?, whereas g∥ is insensitive to ?, and (v) the influence of the lattice distortions on the spectroscopic properties of V3+ ion in α-Al2O3 is pronounced. It appears important for similar ion-crystal cases to consider the lattice distortions in detailed calculations, which take into account the relevant contributions from the SO, SS and SOO interactions. A good agreement between the theoretical and experimental results has been obtained. 相似文献
87.
Twenty-six glassy compositions, belonging to the GexIn6Se94-x and GexIn12Se88-x families of the Ge-In-Se system, were prepared from high purity constiment elements. Differential Scanning Calorimetry (DSC) measurements were carried out on these glasses. The DSC thermograms were used to determine the glass transition temperatures (T
g) for the compositions examined. TheT
g-composition dependence of the GexIn6Se94-x family shows a minimum inT
g at a value of the average coordination number, r, equal to 2.4. For both families of the glasses examined, theT
g-r dependence displays maxima at r=2.75 and r=2.83 for GexIn6Se94-x and GexIn12Se88-x families, respectively. These results are interpreted by using the Phillips model of rigidity percolation and Chemically Ordered Covalent Network (COCN) model. 相似文献
88.
以聚4-甲基戊烯-1(PMP)为膜材质,分别以环己烷、三氯乙烯、四氯乙烯及环已烷/三氯乙烯为溶剂,研究了这些溶液浇铸膜对O_2、N_2、H_2及CO_2等气体的透过行为。结果表明,气体的透过主要发生在PMP的无定形区域,但也在PMP的晶区进行。PMP的Ⅵ型结晶比Ⅰ型结晶具有较低的气体透过活化能。 相似文献
89.
William E. Collins 《Separation & Purification Reviews》2013,42(2):215-253
Proteins are isolated in the chemical process industries for a wide variety of uses. Isolation and separation are often conducted with chromatography. Conventional chromatography of proteins is often tedious and can suffer from poor efficiency and resolution. There is a well-known tradeoff between resolution and speed', Newer methods of protein chromatography seek to diminish the shortcomings of conventional methods. New methods are presently being investigated for process, preparative, and analytical applications. 相似文献
90.
One of the main challenges in membrane gas separation is the plasticizing effect that reduces selectivity. For a better understanding of this phenomenon, the knowledge of the sorption behavior of each component of the mixture is necessary. For this purpose, the sorption thermosyphon apparatus (STA), was successfully designed and tested with gas sorption measurements. One of the main advantages of the STA compared to actual other methods is to ensure concentration uniformity at the headspace using a thermosiphon, as pressure decay is recorded. The equilibrium condition is not disturbed during the sampling and allow the obtention of accurate data at the end of the sorption experiment. To validate the novel system, the sorption, diffusion and permeation coefficients of pure CO2 and CH4, as well as for a CO2/CH4 (50/50) mixture, in polydimethylsiloxane (PDMS) were obtained through STA and other experimental techniques showing good agreement with literature data. 相似文献