Ar原子偶宇称3p5(2P1/2)nl′ [K′]J (l′=1, 3)自电离Rydberg态共振增强激发光谱

用脉冲直流放电产生Ar原子亚稳态3p⁵4s[3/2]₂和3p⁵4s′[1/2]₀．在单光子32500～35600 cm^-1能量范围内, 结合飞行时间质谱技术获得Ar原子共振增强激发光谱．光谱分析表明,所有谱线来源于Ar原子3p⁵4s[3/2]₂和3p⁵4s′[1/2]₀两个亚稳态吸收单个光子向偶宇称np′、nf′自电离Rydberg态序列的跃迁．实验观测到许多新的自电离能级,并获得更精确和系统的能级位置和量子亏损值数据．     

准周期激励与应变超晶格的动力学稳定性

假设超晶格锯齿形沟道对粒子的作用等效为形状相似的周期场作用. 在经典力学框架内,引入正弦平方势,把粒子运动方程化为具有阻尼项和双频激励项的摆方程. 用Melnikov方法对单频激励系统的分叉与混沌进行分析;用Lyapunov方法对双频激励系统的稳定性进行讨论. 结果表明：在弱非线性情况下,双频激励系统存在局域不稳定,且这种不稳定将向全局扩展,直至混沌的出现;导致混沌的双频激励强度远小于单频激励强度;外加一个适当的超声场可望将这种敏感钝化,使系统的稳定性得到改善. 关键词： 超晶格 准周期激励 混沌 稳定性     

不同溶剂中PAH荧光产出对激发波长的依赖

用日立F 45 0 0型荧光分光光度计就石油产品中两种主要的多环芳香族碳氢化合物 (PAH) ,即菲和萘在两种不溶剂即水和二氯甲烷中的荧光产出对激发光波长的依赖进行了研究。结果表明 ,样品溶液的荧光转换效率与激发光波长有十分密切的关系 ,而这种关系又强烈依赖于所用溶剂     

气体激光器射频至微波放电激发的某些规律

本文研究了射频至微波激发的Xe和He-Ne原子激光器及CO₂分子激光器,结合各具体激光器的实验结果对其放电物理进行了讨论,提出获得高效率的关键是有效控制放电空间的电子能量,得出了一些有指导意义的结论.     

多光子成象术中深层图象损耗恢复的研究

本文在分析混浊介质对共焦三维扫描图象衰减的基础上,建立了多光子激发荧光扫描的深层图象恢复的数学模型.依照此模型对深层图象进行依赖组织光学参量的恢复,并给出了猪表皮三维扫描成象的恢复图象.     

Phonons and periodons in IV–VI semiconductor superlattices

We have calculated the phonon and periodon dispersion relations in IV–VI semi-conducting bulk PbTe and SnTe and their superlattice structure. The model used here is a one-dimensional lattice which includes harmonic interactions up to second neighbours as well as on-site nonlinear electron-ion interactions at the anion site. We calculate the phonon and periodon dispersion relations in bulk and PbTe-SnTe superlattice for the transverse optic and acoustic modes using the transfer matrix method. Our analysis has predicted correct nature of the folding of acoustic and confinement of optical phonons at various frequency intervals corresponding to pass and stop bands of the superlattices.     

同位旋激发能研究

在扩展的Skyrme有效相互作用下,利用Hartree-Fock理论研究了同位旋激发能与温度、密度的关系.结果表明同位旋激发能随密度的降低以及温度的增加而降低.同时研究了对称能与同位旋激发能的关系,指出对称能是同位旋激发能的一部分,且占相当大的比重.最后研究了不同的势参数下,同位旋激发能随相对中子过剩的变化关系,发现同位旋激发能较强地依赖于对称能强度系数,而对不可压缩系数以及有效质量不太敏感.从而为实验上通过研究同位旋激发能来提取核物质状态方程中的对称能部分指出了一条途径.     

Kinematically complete final state investigations of molecular photodissociation: two- and three-body decay of laser-prepared H 3 3 s ? 2 A 1 '

We have performed kinematically complete investigations of molecular photodissociation of triatomic hydrogen in a fast beam translational spectrometer recently built in Freiburg. The apparatus allows us to investigate laser-induced dissociation of neutral molecules into two, three, or more neutral products. The fragments are detected in coincidence and their vectorial momenta in the center-of-mass frame are determined. We demonstrate the potential of the method at the fragmentation of the 3 s ² A ₁ ^′ ( N = 1, K = 0) state of triatomic hydrogen. In this state, three-body decay into ground state hydrogen atoms H+H+H, two-body predissociation into H+H ₂ (v , J), and photoemission to the H ₃ ground state surface with subsequent two-body decay are competing channels. In the case of two-body predissociation, we determine the rovibrational population in the H ₂ (v , J) fragment. The vibrational distribution of H ₂ is compared with approximate theoretical predictions. For three-body decay, we measure the six-fold differential photodissociation cross-section. To determine accurate final state distributions, the geometric collection efficiency of the apparatus is calculated by a Monte Carlo simulation, and the raw data are corrected for apparatus efficiency. The final state momentum distribution shows pronounced correlation patterns which are characteristic for the dissociation mechanism. For a three-body decay process with a discrete kinetic energy release we have developed a novel data reduction procedure based on the detection of two fragments. The final state distribution determined by this independent method agrees extremely well with that observed in the triple-coincidence data. In addition, this method allows us to fully explore the phase space of the final state and to determine the branching ratios between the two- and three-body decay processes. Received 29 March 2001     

Plasmon Mechanism of Overdense Plasma Heating

This paper attempts to introduce an effective mechanism of plasma heating of an overdense plasma layer. This mechanism is directly related to the phenomena of anomalous transparency of an overdense plasma layer. High temperature is achieved due to the resonant excitation of the coupled surface waves on both sides of the plasma layer. The dissipative energy of the collisional effects appears as an effective heating source in this mechanism. The solutions of the heat equation under the resonant situations are obtained in the steady and unsteady states conditions. The main factors, affecting the considered plasma heating mechanism, are also discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

X-ray diffraction in AT-cut quartz single crystal at acoustic excitation at the fundamental frequency

X-ray diffraction on different atomic planes of an AT-cut quartz crystal is studied experimentally in the Laue geometry in case of excitation by acoustic waves at the first resonant (fundamental) frequency. Acoustic waves lead to an increase in the integral intensity of the reflection-diffracted beam. The amplification coefficients in reflection are measured in dependence on the amplitude of a.c. voltage applied to the crystal at the resonant frequency. The frontal distributions of the intensity of the beam diffracted in the reflection direction are obtained for different atomic planes.