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381.
382.
Elena Achkasova 《Journal of Molecular Spectroscopy》2006,237(1):70-75
The rotationally resolved vibronic bands in the forbidden electronic transition of the cumulene carbene C3H2 have been observed in the gas phase by cavity ring down absorption spectroscopy through a supersonic planar plasma with allene as precursor. The band detected in the 16 223 cm−1 region is a result of vibronic interaction and is assigned to a combination of a1 and b2 vibrations with a frequency around 2250 cm−1. Another vibronic band near 15 810 cm−1 has an unusual rotational structure because the Ka = 0-1 subband is absent. It is assigned to a combination of a1 and b1 vibrations, ∼1850 cm−1, which borrow intensity from the near lying state due to a-type Coriolis coupling. A rotational analysis using a conventional Hamiltonian for an asymmetric top molecule yields molecular constants for the vibrational excited levels of the Ã1A2 state, which were used for the determination of the geometry. The stronger transition of C3H2, measured in a neon matrix in the 16 161-24 802 cm−1 range, was not detected. The reason for this is a short lifetime of the state, leading to line broadening. 相似文献
383.
Olga Leshchishina Samir Kassi Laurence S. Rothman Alain Campargue 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(15):2236-2245
The CW-Cavity Ring Down Spectroscopy (CW-CRDS) technique has been used to record the high sensitivity absorption spectrum of the a1Δg-X3Σg− band of oxygen near 1.27 μm. The spectra were obtained between 7640 and 7917 cm−1 with “natural” oxygen and with a sample highly enriched in 18O. The absolute intensities of 376 and 643 oxygen transitions were measured in the two spectra. They include the a1Δg−X3Σg− (0-0) bands of 16O2, 16O18O, 16O17O, 17O18O and 18O2. The (0-0) bands of 16O2 and 18O2 show weak quadrupole transitions with line intensities ranging from 1×10−30 to 1.9×10−28 cm/molecule. They are accompanied by the a1Δg−X3Σg− (1-1) hot bands, which are reported for the first time. The line profiles of the transitions of the 16O17O and 17O18O isotopologues were observed to be broadened due to an unresolved magnetic hyperfine structure. Accurate spectroscopic parameters of the different energy levels involved in the observed bands were derived from a global fit of the observed line positions, combined with microwave and Raman measurements available in the literature. 相似文献
384.
Resonant excitation of multi-photon transitions in one-atom cavity QED, from the ground state to an excited dressed state, induce an additional semiclassical Rabi splitting. This “dressing of the dressed states” arises from a multi-photon blockade, where, for sufficiently strong coupling, detunings, brought about by the nonlinearity of the Jaynes-Cummings model, inhibit absorption of additional photons. We show how this behavior is revealed in the spectrum and photon correlations of the quasi-elastically scattered light. Explicit results are presented for the two-photon case. 相似文献
385.
Quantum state engineering by superpositions of coherent states along a straight line with a single atomic state measurement 总被引:1,自引:0,他引:1
A new scheme is proposed for preparation of a type of nonclassical state in cavity QED. In the scheme, an atom either flying through or trapped within a cavity, is controlled by the classical Stark effect; this makes it interact alternately with a (resonant) classical field and with the (dispersive) cavity field. The cavity field, which allows an arbitrary displacement operation during the process, after the detection on the atom, finally collapses to the specific superpositions of coherent states, with their weighting factors controllable. The scheme is also applied for preparation of superpositions of motional coherent states for a trapped ion. The scheme is in contrast to all the previous ones, and thus provides a new perspective for quantum state engineering. 相似文献
386.
E.R. Tracy A.J. BrizardD. Johnston A.N. KaufmanA.S. Richardson N. Zobin 《Communications in Nonlinear Science & Numerical Simulation》2012,17(5):2161-2170
Ray tracing in the presence of linear mode conversion leads to a ‘splitting’ of an incoming ray into two outgoing rays. When the rays are confined to a cavity, the rays can re-enter the conversion region many times, leading to iterated conversion. In this paper, we present new methods for the analysis of this problem. These involve a shift from local to global methods of analysis, and a shift in emphasis from the study of ray evolution in the dispersion surface to the study of the iterated dynamics of rays crossing the conversion surface. The analytical methods are quite general and can be applied in phase spaces of arbitrary dimension. In two spatial dimensions, (x, y), i.e. with a four-dimensional ray space, (x, y, kx, ky), rays are confined to three-dimensional regions called rooms, with one room for each wave type. In these rooms the rays do not cross, but when they intersect the conversion surface a family of converted rays is produced in the other room. The use of rooms allows a full view of the phase space dynamics of the iterated conversion of ray families. A simple two-dimensional model, inspired by the Budden resonance model, is presented as an example of these ideas. 相似文献
387.
G. De Vahl Davis 《国际流体数值方法杂志》1983,3(3):249-264
Details are given of the computational method used to obtain an accurate solution of the equations describing two-dimensional natural convection in a square cavity with differentially heated side walls. Second-order, central difference approximations were used. Mesh refnement and extrapolation led to solutions for 103?Ra?10 6 which are believed to be accurate to better than 1 per cent at the highest Rayleigh number and down to one-tenth of that at the lowest value. 相似文献
388.
利用激光腔内共振衰减技术 (CRDS) ,获取了CH2 CHO自由基的近紫外吸收光谱 .在此吸收光谱中 ,有一从 2 8786cm-1起始的振动 电子带 ,和一随能量而增加的宽吸收背景 .此CRDS吸收光谱和以前的低分辨吸收光谱相一致 ;其振动 电子吸收峰位置和在激光诱导荧光光谱及光解产物谱中的峰位置相吻合 . 相似文献
389.
A. Kress F. Hofbauer N. Reinelt H.J. Krenner M. Bichler D. Schuh R. Meyer G. Abstreiter J.J. Finley 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):351
We demonstrate our ability to control and manipulate the optical modes in 2D Photonic Crystal Defect cavities and investigate their coupling to InGaAs self-assembled quantum dots. Our results enable us to probe the nature of individual cavity modes and directly investigate cavity QED phenomena. For the lowest mode volume cavities investigated, consisting of a single missing air hole within a hexagonal lattice, we have measured a clear Purcell enhancement of the light-matter interaction in the weak coupling regime. For QDs on-resonance with localized cavity modes this translates to a shortening of the quantum dot spontaneous emission lifetime by a factor 2 when compared to off-resonance dots. 相似文献
390.
A numerical and an experimental study of the flow of an incompressible fluid in a polar cavity is presented. The experiments included flow visualization, in two perpendicular planes, and quantitative measurements of the velocity field by a laser Doppler anemometer. Measurements were done for two ranges of Reynolds numbers; about 60 and about 350. The stream function-vorticity form of the governing equations was approximated by upwind or central finite-differences. Both types of finite-difference approximations were solved by a multi-grid method. Numerical solutions were computed on a sequence of grids and the relative accuracy of the solutions was studied. Our most accurate numerical solutions had an estimated error of 0.1 per cent and 1 per cent for Re = 60 and Re = 350, respectively. It was also noted that the solution to the second order finite difference equations was more accurate, compared to the solution to the first order equations, only if fine enough meshes were used. The possibility of using extrapolations to improve accuracy was also considered. Extrapolated solutions were found to be valid only if solutions computed on fine enough meshes were used. The numerical and the experimental results were found to be in very good agreement. 相似文献