ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTheory of dynamic absorption spectroscopy nonstationary states. 4. Application to 12-fs resonant impulsive Raman bacteriorhodopsinW. Thomas Pollard, Susan L. Dexheimer, Qing Wang, Linda A. Peteanu, Charles V. Shank, and Richard MathiesCite this: J. Phys. Chem. 1992, 96, 15, 6147–6158Publication Date (Print):July 1, 1992Publication History Published online1 May 2002Published inissue 1 July...

A convenient, metal-free intramolecular aminofluorination of alkenes has been developed. Employing readily available PhI(OPiv)2 and hydrogen fluoride–pyridine in the presence BF3·OEt2, tosyl-protected pent-4-en-1-amines were converted to 3-F-piperidines one step good yields as well high stereoselectivity.

A novel approach is proposed in this paper for earthquake-induced building collapse extraction based on the optimization of polarimetric contrast enhancement (OPCE). This method can realize a quick damage assessment since data it requires one post-event fully Synthetic Aperture Radar (PolSAR) image. In method, collapsed recognized as clutter and optimal polarization states are determined samples with different orientation angles. For comparison, another methodology, synthesis technology also...

This paper proposes a miniature optically pumped cesium-beam atomic frequency standard with volume of 38.4 l and weight 28 kg examines the main factors that affect its signal-to-noise ratio (SNR). Methods to improve SNR are proposed, which short-term instability: installing collimator at exit cesium oven, using beam fluorescence spectrum fiber-coupled output stabilize laser frequency, 4–5 cycling transition D2 line for detection. We also examine several shifts long-term instability detail...

We report a simple and robust Doppler-free spectroscopic technique to stabilize laser frequency the atomic transition. By employing Doppler Effect on beam, we obtained very stable dispersive signal with high signal-to-noise ratio no Doppler-background, which served as an error electronically without modulation. For validating performance of this technique, locked DFB (133)Cs D2 line observed efficient suppression noise long-term reduction drifts in laboratory environment.

The sensor calibration accuracy is an important indicator of SAR satellite system's performance and data quality. Towards geometric radiometric Radarsat- 2 (RS2), this paper researched the procedure key techniques space-borne field calibration, including corner reflectors' (CRs) design, CRs' arrangement in field, acquirement peak RCS value surveying scheme. Besides, RS2's was validated, giving reference for its quantitative application.

Synthetic aperture radar (SAR) is an effective tool in detecting building damage. At present, more and studies detect damage using a single post-event fully polarimetric SAR (PolSAR) image, because it permits faster convenient detection work. However, the existence of non-buildings obliquely-oriented buildings disaster areas presents challenge for obtaining accurate results only PolSAR data. To solve these problems, new method proposed this work to completely collapsed full polarization...

Compared to other commercial atomic clocks in the time keeping field, greatest advantage of cesium beam is their superior long-term stability. magnetic state-selection clocks, optically pumped have more interacting atoms, which results better stability potential. To achieve good stability, we propose methods including stabilization laser power and reconstruction circuits. They play a key role clocks. After 75 days continuous running measurement, released 5-day (7×10-15 Allan deviation) our...

A beam source is proposed for the production of an intense cold cesium atomic that can be used in clocks. The based on a two-dimensional magneto-optical trap (2D-MOT), but introduces hollow cooling and pushing lights axial direction to create 2D+-MOT, which separates functions while low-power light pushes atoms out form beam. This reduces shift due leakage retains longitudinal increase flux compared with conventional 2D+-MOT scheme. specifics design are investigated, velocity calculated,...

The coupling mechanism between crossed beams energy transfer and stimulated Brillouin scattering in homogeneous plasmas are studied by theoretical analysis, fluid simulations particle cell(PIC) simulations. numerical models of laser plasma instabilities constructed solving equations with Schodinger form, the simulation results confirmed theory PIC simulations.In parameter regime when pump depletion does not occur CBET reflectivity SBS is lower than 1%, will be affected CBET, gain still agree...

A map from the charged Dirac oscillator on a noncommutative plane interacting with homogeneous magnetic field onto quantum optics model is proposed. We find that both anti-Jaynes-Cummings (AJC) and Jaynes-Cummings (JC) interactions are included in this mapped model. competition between AJC JC will happen when intensity of changes. Contrary to previous studies, symmetrical since phonons take part only associated excitation oscillator. Furthermore, experience phase transition crosses critical...

As optical frequency standard [1]-[4] and comb developed with quite high precision(10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-18</sup> or 10 xmlns:xlink="http://www.w3.org/1999/xlink">-19</sup> ) commercial H-maser good short-term stability(10 xmlns:xlink="http://www.w3.org/1999/xlink">-15</sup> ), the only core competitiveness of Cesium beam standards(CBFS) are reliability long-term stability today. We a performance portable optically...

Earthquake is one of the most catastrophic disasters to affect mankind especially in urban areas. Reliable and fast collapsed building detection vitally important timely rescue scientific decision making. A modified method for buildings proposed this paper by jointly using interferometric information polarimetric information. The was tested on two single-polarimetric ALOS PALSAR images fully Radarsat-2 image from Yushu earthquake Qinghai province China occurred 2010. After compared with...

The key point of the variational-cumulant expansion is determination variational parameter. In this paper, we present improved mean-field hypothesis (IMFH) which base to determine new method derived from IMFH shows advantage over previous methods. critical temperature and some thermal dynamical functions for Heisenberg model are calculated with method.

In this paper, we present a linewidth locking method to control the microwave power in optically pumped cesium-beam frequency standards. The responses of tubes and classical are analyzed compared against field. Due wide probability distribution atomic velocity resulting from optical state preparation detection, Ramsey pattern is sensitive power. results can be used instead using traditional extremum method. advantages new discussed, named When well controlled at low level by method,...

We report the scheme and preliminary experiments of optically pumped cold cesium beam atomic clock based on two-dimensional magneto-optical trap. It is predicted that Ramsey fringe linewidth such can reach 25Hz, while output frequency stability expected to be σy(τ)=2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-14</sup> /√{τ}.

SummaryThe short-term frequency stability of compact optically pumped cesium beam atomic clock is directly affected by signal-to-noise ratio its Ramsey spectrum. In this paper, the noise sources are analyzed. On basis parameters in our clock, contributions different within 1Hz bandwidth studied, and corresponding ratios calculated. According to evaluation results, one main detection laser.