High-resolution study of the ν1/ν5 and 2ν1/ν1+ν5 P-H stretching bands of PH2D

The P-H stretching bands ν₁/ν₅ and 2ν₁/ν₁+ν₅ were recorded using a Bruker 120 HR interferometer with a resolution of 0.0042 and 0.0088 cm⁻¹, respectively, and analyzed. From the fits 33 and 50, respectively, vibrational, rotational, centrifugal distortion, and resonance interaction parameters were obtained. These reproduce 668 and 497 rovibrational energies of the pairs of states ν₁/ν₅ and 2ν₁/ν₁+ν₅ with experimental accuracies, rms=0.00016 and , respectively. “Local mode” behavior of the PH₂ fragment is established and discussed in detail.     

Design of the Collective Thomson Scattering Diagnostics for Large Helical Device Using a Quasi-Optical Frequency Tunable Gyrotron as a Radiation Source

Collective Thomson scattering technique based on high power laser has already proved its ability in measuring the ion (bulk and fast) temperature (T _i) in fusion plasma devices like tokamaks and stellarators. This paper present first trial to implement collective Thomson scattering diagnostic based on quasi-optical gyrotron as a source of radiation. It was found utilization of this wavelength band gives more flexibility in diagnostic port arrangement.     

Spectroscopic study of a D.C. discharge in an argon-silane-nitrogen gas mixture under silicon nitride thin film deposition conditions

A detailed experimental investigation of a D.C. discharge in an argon-silanenitrogen gas mixture is undertaken using mainly spatially resolved spectroscopy. Discharge parameters are studied as functions of the gas mixture composition, and the influence of nitrogen concentration on the dissociation phenomena of SiH₄ and on dehydrogenation mechanisms of the growing film surface is particularly discussed.     

Effects of transient local heating of spatially and spectrally heterogeneous biotissue by short laser pulses

Summary A new laser method for the spectroscopy of locally absorbing microvolumes much smaller than the radiation wavelength in size is discussed. Such an absorption is characteristic of biotissues and other biological media. The method allows data to be obtained on the size of local microvolumes absorbing at the radiation wavelength. It is based on the possibility of transient overheating of the microvolumes by means of an ultrashort pulse with a duration much shorter than the time it takes to heat to diffuse from the microvolumes. The pulse-heated microvolumes must have an altered refractive index leading to an additional scatter of another probe laser pulse, that is made to irradiate the medium under study after some delay. Besides, the locally heated microvolumes will have temperature-altered fluorescence induced either by the heating laser pulse or by an additional probe pulse at another wavelength more suitable for fluorescence excitation. Due to the relevance of its scientific content, this paper has been given priority by the Journal Direction.     

北京FEL电子束时间分辨能谱仪设计

从Wiggler出来的电子束,经过180°偏转后进人能谱和时间谱诊断系统。180°偏转段设计成既可等时又可消色散传输,等时传输是为满足对电子束微脉冲时间谱诊断,消色散是为满足电子束宏脉冲时间分辨能谱诊断。宏脉冲时间分辨能谱诊断系统由四台匹配透镜、双缝仪、扫描偏转线圈、90°对称双聚焦分析磁铁、位于焦平面的荧光靶、带有象增强器的视频摄象系统和在线计算机图象处理系统组成,其能量分辨好于1000,时间分辨好于60ns。     

Molecular photodynamics involved in multi-photon excitation fluorescence microscopy

We present a simple model for calculating the fluorescence generated by the multi-photon excitation (MPE) of molecules in solution. The model takes into account internal molecular dynamics such as ground-state depletion due to inter-system crossing (ISC), as well as external molecular dynamics associated with diffusion into and out of an excitation volume confined in 3-dimensions. Internal and external molecular dynamics are combined by using a technique of linearization of a modified diffusion equation which takes into account the possibility of concentration depletion due to photobleaching. In addition, we discuss the phenomenon of pulse saturation which effectively limits the molecular excitation rate constant in the case of short pulsed excitation. Our results are specifically applied in the context of fluorescence autocorrelation functions and single-molecule detection. In the latter case, we discuss some consequences of high-order multi-photon photobleaching. Finally, we include three appendices to rigorously define the temporal and spatial profiles of an arbitrary excitation beam, and also to discuss some properties of an exact evaluation of concentration depletion due to photobleaching. Received: 9 March 1998 / Accepted: 20 April 1998     

Pinhole transmission grating spectrometer of X-ray picosecond frame

The structure principle and performance of the measure system of three-dimensional resolution of time, space and spectrum for laser-produced plasma are presented. The typical experimental results are also given. Project supported by the National Natural Science Foundation of China and Science Foundation of Chinese Academy of Engineeing Physics.     

SU(3) coupling schemes for odd-odd nuclei in the interacting boson – fermion – fermion model with both odd proton and odd neutron in natural parity orbits

The SU^BFF(3) dynamical symmetry limits of interacting boson – fermion – fermion model are identified and they are appropriate for heavy deformed odd – odd nuclei for configurations with both the odd proton and odd neutron occupying all the natural parity orbits in the corresponding valence shells. There are three symmetry limits and their correspondence with two quasi-particle (proton-neutron) Nilsson configurations is established; one of the limits mixes both Nilsson n_z's and Λ's and other two limits mix only Nilsson Λ's. The ¹⁹¹Ir (d,t) ¹⁹⁰Ir single nucleon transfer spectroscopic strengths are well described by one of the symmetry limits that mixes only Nilsson Λ's. Received: 22 June 1998     

用二维CCD系统测量光束质量的实验研究

 建立了一套二维面阵CCD光束质量诊断系统, 测量了磷酸盐钕玻璃板条激光器自由振荡和调Q输出激光的光束质量因子M²。该测量系统经过数据校核, 所得测量结果是正确的。     

采用对数比处理技术的同步光位置测量系统

 对于双丝型同步光位置检测器，对数比处理技术较差比和处理技术具有更宽的线性范围和动态范围。利用美国BB公司的高精度对数运算放大器LOG112实现电流电压转换，研制了一种采用对数比处理技术的同步光位置测量系统，垂直方向光位置测量分辨率约为1 μm，线性范围大于±3 mm。与合肥同步辐射光源原有同步光位置测量系统相比，具有较高的性价比。