Investigations on optically controlled millimeter wave Gunn oscillators

There is a growing interest in optically controlled millimeter wave oscillators. In this paper, we have investigated the external-circuit impedances of an optically controlled millimeter wave subharmonic Gunn diode oscillator, which is illuminated by GaAs/GaAlAs laser beam. The variation of the external-circuit impedances looking outward from the Gunn diode with respect to the optical injection plasma density are calculated based on a field analysis method. The results give some useful conclusions for optically controlled millimeter wave Gunn diode oscillator design. Experimentally an optical tuning frequency shift of 7MHz is achieved at W-band.     

二（2,4,4—三甲基戊基）膦酸稀土配合物的振动光谱

测定了二（２，４，４－三甲基戊基）膦酸（ＢＴＭＰＰＡ）及其稀土配合物Ｌｎ（ＢＴＭＰＰ）３在４０００～５０ｃｍ＾－１光谱区内的ＦＴ－ＩＲ光谱和部分配合物的激光拉曼光谱，对其谱带进行了经验归属。发现稀土氧键具有较高的离子键特性。由Ｌｎ－Ｏ伸缩振动频率值算出其近似力常数约８ｍ ｄｙｎ／ｎｍ。     

BRDF reference standards for the infrared

A comparison between various recommended reference standards of diffuse reflectance in the IR is presented. It is shown that at a wavelength of 10.6 μm sulfur is the most Lambertian of the tested samples, although its powdery consistence makes it less suitable for use as a standard. Flame sprayed aluminum, with or without gold coating, also approaches a Lambertian surface and is suitable for use as a standard for BRDF measurements at 10.6 μm. Results for the BRDF of sulfur, gold-coated sandpaper, a commercial diffuse gold surface (by Labsphere) and flame sprayed aluminum are presented.     

Solvation dynamics in methanol: Experimental and molecular dynamics simulation studies

We have investigated the ultrafast dynamics of methanol by time dependent fluorescent shift experiments and molecular dynamic simulations. The experiments were performed with two different probe molecules, 1-aminonaphthalene and coumarin 153. The molecular dynamic simulations employed these probes as well as small atomic and diatomic solutes. We find a previously unobserved fast decay component in the solvation response of methanol. The molecular dynamics results are in good agreement with this experimental result. The origin of this fast response and the linearity of the solvent response are discussed.     

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Simultaneous jumps in two two-level atoms

We demonstrate the importance of collective behaviour in two identical two-level atoms. When the atoms become very close together a cascade three-level atom analysis can be adopted to show the increasing possibility of simultaneous jumps. Due to the dipole-dipole interaction the intermediate one-atom excited state is detuned by a large amount when the atoms are close together but leaving the upper two-atom excited state in two-photon resonance. The relative importance of multiple jumps compared with stepwise independent jumps is then changed dramatically.     

6 j symbols for $U_q (\mathfrak{s}\mathfrak{l}_2 )$U_q (\mathfrak{s}\mathfrak{l}_2 ) and non-Euclidean tetrahedra

We relate the semiclassical asymptotics of the 6j symbols for the quantized enveloping algebra at q a root of unity (resp. q real positive) to the geometry of spherical (resp. hyperbolic) tetrahedra.     

E-Plane Forked T-Junction Analyzed by FDTD Method

By using the Finite-Difference Time-Domain method (FDTD), several E-plane Forked T-junctions are analyzed. Good agreement between the calculation and the experimental results given by [5][11] is found. The scattering parameters of these T-junctions are obtained by applying the Fast-Fourier Transform method (FFT).     

An effective method of accelerating Bose gases using magnetic coils

Based on the experimental device which is a non-uniform magnetic field to trap an atom, we show how to obtain a certain velocity of a Bose gas by controlling the magnetic coils. By comparing the relationship of the different current supply and delay time versus the ultimate velocity of the atom, we theoretically predict the method of accelerating the gases to an expected velocity. This method is of great convenience and significance for the applications in cold atom physics and precision measurements.