Anomalous elasticity of an ordered lamellar liquid foam

We investigate experimentally the linear viscoelastic properties of a lamellar liquid foam as a function of the cell size and spatial organisation. The system consists of multilamellar vesicles generated by a simple shear flow on a lyotropic lamellar phase. The vesicles can be prepared either in an amorphous or a spatially ordered state. Their size is easily tunable in the range R = 0.5-15 μm. Whereas the shear modulus of the amorphous lamellar foam is alike that of usual liquid foams or concentrated emulsions and scales linearly with 1/R, the elastic modulus of the ordered foam is almost independent of the cell size. This result --probably the first describing the elasticity of an ordered foam-like system-- remains unexplained. Received 7 August 2000     

Experiments of Multi-Level Read-Only Recording Using Readout Signal Wave-Shape Modulation

An innovative multilevel read-only recording method is proposed. In this method, a short pit/land is deliberately inserted to the original land/pit. This modifies the wave-shape of readout signM. Taking the wave-shape as the symbol of level detection, a signal wave-shape modulation （SWSM） multilevel method is realized. This method is carried out and validated on the DVD read-only manufacture and readout system. A capacity of 15 GB can be expected, and a bit error rate of 10-4 is achieved. The capacity can meet the demand of high definition movie publication. This method also provides a potential multi-level solution for other storage formats and systems.     

Gas monitoring in the process industry using diode laser spectroscopy

2 , CO, NH₃, HCl and HF are described together with measurements from several installations. The monitors show continuous measurements with fast response and good sensitivity, all of which is difficult to obtain with conventional techniques such as wet chemical analysis. Received: 19 March 1998/Revised version: 2 June 1998     

Optically detected carrier transport in III/V semiconductor QW structures: experiments, model calculations and applications in fast 1.55 μm laser devices

Received: 24 September 1997     

Iron-aluminum pairs in silicon

Iron-aluminum pairs in silicon are investigated with conventional and optically detected electron paramagnetic resonance (EPR). For the trigonal and orthorhombic pairs known from previous EPR measurements we found for the first time optical absorption bands by measuring their magnetic circular dichroism of the absorption (MCDA). Direct experimental evidence is presented for the configurational bistability of both pairs by showing that the MCDA of the trigonal configuration can be transformed into that of the orthorhombic configuration by the combined effect of light and temperature. A new trigonal pair was discovered by conventional EPR having the same EPR intensity as the known one. Total energy calculations of various (Fe_i-Al_s) pair configurations show that two trigonal (Fe_i-Al_s)⁰ pairs with different Fe_i-Al_s separations have almost the same binding energy and should occur with the same probability. Fe _i ⁺ is always on a tetrahedral interstitial site, while Al _s ^– is nearest neighbor along 111 in one pair, second nearest neighbor in the other one with one silicon lattice site in between.Dedicated to H.-J. Queisser on the occasion of his 60th birthday     

Physical Explanation of Influence of Twin and Three Satellite Formation Mode on the Accuracy of Earth's Gravitational Field

The simulated results of the influence of twin and three satellite formation mode on the accuracy of GRACE Earth＇s gravitational field are interpreted from the viewpoint of physics. Because the effective satellite observation information of Earth＇s gravitational field recovery from three-satellite formation mode is only one time more than that of twin satellites, the improvement of the accuracy of Earth＇s gravitational field is far lower than one order of magnitude based on the simple two-times differences between three satellites. Three efficient ways of improving largely the accuracy of measurement of the Earth＇s gravitational field in the future international satellite gravity measurement programme, including proper decrease of satellite orbital altitude, the increase of accuracy from key payloads and an innovation of satellite observation mode are proposed.     

Cooling and Trapping 88Sr Atoms with 461nm Laser

We report the experimental realization of a ^88Sr magneto-optical trap （MOT） operating at the wavelength of 461 nm. The MOT is loaded via a 32 cm long spin-flip type Zeeman slower which enhances the MOT population by a factor of 22. The total laser power available in our experiment is about 300mW. We have trapped 1.6 × 10^8 ^88 Sr atoms with a 679nm and 707nm repumping laser. The two repumping lasers enhance the trap population and trap lifetime by factors of 11 and 7, respectively. The ^88 Sr cloud has a temperature of about 2.3 mK, measured by recording the time evolution of the absorption signal.     

Monte Carlo Study on Singly Tagged D Mesons at BES-III

We present Monte Carlo studies on the singly tagged D mesons, which are crucial in the absolute measurements of D meson decays, based on a full Monte Carlo simulation for the BES-III detector, with the BES-III Offline Software System. The expected detection efficiencies and mass resolutions of the tagged D mesons are well estimated.     

Experimental Sensitivities on Searching for Rare and Forbidden Decays of Charm Mesons at BES-III

We discuss the Monte Carlo studies of searching for the rare and forbidden pure-leptonic and semi-leptonic decays of D^+,0 and D⁺_s mesons, based on a full Monte Carlo simulation for the BES-III detector, with the BES-III Offline Software System. The experimental sensitivities of searching for 36 rare and forbidden charm meson decays are estimated.     

Modelocked quantum dot vertical external cavity surface emitting laser

We report the first successful modelocking of a vertical external cavity surface emitting laser (VECSEL) with a quantum dot (QD) gain region. The VECSEL has a total of 35 QD-layers with an emission wavelength of about 1060 nm. In SESAM modelocked operation, we obtain an average output power of 27.4 mW with 18-ps pulses at a repetition rate of 2.57 GHz. This QD-VECSEL is used as-grown on a 450 μm thick substrate, which limits the average output power.