An interpretion of the wave-packet-collapse (WPC) in the system of quantum mechanics is given. We find a connection between the WPC and the limitation to the measurement precision determined by the quantum fluctuation. A simple and explicit relation about them is obtained.

The n-type GaAs/Al_{x}Ga_{1-x}As multiple quantum well infrared photodetectors have been demonstrated without any grating couplers. We have achieved a responsivity R_{v} of 1.7×10^{5}V/W and a detectivity D_{λ}^{*} of 4.0×10^{10} cm (Hz)^{1/2}/W for a wavelength of 8.4 μm at a temperature T = 77 K in normal incidence.

Effective cavity length method is introduced to vertical cavity surface emitting laser for characterizing some properties, including reflectivity, FWHM, mode wavelength and thresh-old gain. Some experiment results are demonstrated, showing the agreement of theoretical analysis with experiment.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

The general expressions of the elastic fields induced by straight dislocations in quasicrystals have been given according to Eshelby's method which was used to treat the anisotropic elasticity of dislocations in crystals. As an example, the elastic displacement vector, the stress tensor and the elastic energy density of a screw dislocation line lying on the quasiperiodic plane of decagonal quasicrystals are calculated.

A simplified one-dimensional model was proposed to treat the gas dynamic problems in a supersonic jet, which was used to produce radicals cooled by supersonic expansion, Based on this model, the gas dynamic equations can be integrated directly to obtain the evolution or the translational temperature and the rotational temperature of free radicals as well as the molecule density. The results show that the heating position where the radicals are generated and the initial rotational temperature of radicals have little effect on the rotational temperature at the down stream detection point, if the heating position is close to the nozzle orifice.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

Band structures of Si-C and Si-C-Ge alloys are calculated by using the ab initio LMTO (linear muffin-tin orbital) method within the framework of atomic-sphere approximation. The effects of different atomic configuration and lattice relaxation on the band structure of alloys are taken into account. The results show that for large concentrations of C in Si and Si-Ge, the band gap increases monotonically, while for small concentrations of C in Si and Si-Ge, the band gap shrinks. The lattice relaxation further reduces the band gap. The possible explanations for the reduction of band gap of Si-C and Si-C-Ge alloya are presented.

The continuum generalization of the one-dimensional Heisenberg-Ising model is studied by the bosonization method. With reference to the results of the renormalization group theory, we are able to obtain the critical exponents by considering the influence of the large momentum transfer and improve Luther and Peschel's results to the next order. A comparison of the exact result of the lattice model with that of the continuum model by various treatments are also given.

The physical meaning of the transcendental function in traditional thermally stimulated current (TSC) equation of electric dipoles with a single activation energy was first analyzed. Then a simple formula obtained directly from the tested TSC for calculating activation energy parameter, etc., was deduced. Numerical calculation showed that the exact TSC agrees with the approximated one very well. Further analysis found a limiting condition for the discrete to continuous activation energy density distribution and a criterion for discriminating the contributions to TSC by depolarization of the dipoles with multi-activation energy from those with a single one.

The electroluminescence of Ge_{x}Si_{1-x}/Si single quantum well was measured at temper-atures above room temperature along the growth direction and the direction normal to it. TO and NP peaks were resolved.

Raman scattering of several organic charge-transfer salts containing BEDT-TTF of ET cation such as κ-ET_{2}Cu(NCS)_{2}, β_{L}-ET_{2}I_{3}, α-ET_{3}Cl_{2}. 2H_{2}O, a-ET_{3} (ReO_{4})_{2} and ETFeBr4 were measured and the variations of the frequencies of C=C bonds of ET molecules on charge transfer were observed. It is found that the energy of C=C stretch modes shows a general downward shift upon ionisation of ET molecule. In addition, we have observed the Raman spectra of C=C stretch vibratinns in κ-ET_{2}Cu(NCS)_{2} single crystal on going through T_{c}(～10.4 K) and found no detectable effect during the superconducting phase transition.

8000 CROSSDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

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