第二届全国光散射学术会议简讯

第二届全国光散射学术会议于1983年10月12日至16日在苏州大学举行.出席会议的有55个单位的110名代表.会议宣读交流了论文近80篇,其中特邀报告三篇. 报告主要涉及到物理、化学、生物、矿物、谱学、材料、仪器和测试方法等学科.关于导波光的散射、布里渊散射、受激光散射的特邀报告引起了较大兴趣.物理方面的工作主要有:喇曼散射研究固体(主要是铁电体、半导体和非晶态)的晶格振动模和结构相变;高压下晶体的喇曼光谱及压力相变;晶体中的布里渊散射;非线性喇曼散射涉及到相干反斯托克斯喇曼散射,高压氢气、液态空气和光纤中的受激光散射等目前…     

结晶紫、碱性品红、染料1555吸附在银胶上的表面增强喇曼散射的激发波长关系

本文通过研究在不同激发波长下吸附在银胶上的结晶紫、碱性品红、染料1555的表面增强喇曼散射散射强度的变化,分析了普通喇曼散射、表面增强喇曼散射及表面增强共振喇曼散射之间的联系与不同。     

F-P腔喇曼光纤激光器的实验研究

近年来,随着社会信息传输量的急剧增加,人们对喇曼光纤放大器的研究越来越重视,因为它可放大掺铒光纤放大器所不能放大的波段．由于喇曼光纤放大器基于受激喇曼散射效应,一般具有较高的泵浦阈值,需要较大功率的泵浦源．目前较为适用的泵浦方法有两种：采用多个半导体耦合复用和利     

固体的光散射讲座第五讲 共振喇曼散射

共振喇曼散射能够提供的信息和普通喇曼散射很不相同.在普通喇曼散射里,入射光频率和散射光频率并不重要,重要的是散射光对入射光的频移、光的波矢和偏振态等,人们正是根据这些信息,来研究分子、液体和固体中的激发态,这些激发态的能量最多比基态大约只高出5 ×10-2eV.在共振喇曼散射里,除了上述这些信息外,入射光和散射光的频率也上升到重要的地位,只有当入射光子能量与材料体系的某个激发态能量很接近时,才能出现共振喇曼散射.在可见光区域内,光子能量范围大约是1-3eV.因此,利用共振喇曼散射,人们能够有选择地去研究特定激发态的性质.共…     

SiC纳米晶须的光致发光研究

纳米碳化硅晶须作为一维半导体,其光学性质一直受到关注。研究结果显示,在Ar^ 激光（514．5nm)激发下,纳米碳化硅晶须室温下发出极其强烈的红光,这种发光导致喇曼光散射消失,瑞利弹性散射极度减弱,由于低维半导体的体表面大,对称平移受到一定程度的破坏,应该产生大量的缺陷,其发光也应该是表面发光或缺陷发光,但分析表明这可能是低维半导体碳化硅室温下首次发现的极其稳定的强束缚激子或表面发光现象。对其发光机制给予讨论。并且探讨了合适条件下出现喇曼受激辐射,初步认为喇曼散射截面的增大会促进喇曼受激辐射的产生。     

XeCl准分子激光在铅蒸气中的受激喇曼散射

研究了XeCl准分子激光在铅蒸气中的喇曼散射的输出能量及转换效率的参数依赖关系,得到能量～120mJ、峰值功率～2MW的喇曼光输出脉冲.观察到喇曼光脉冲波形上的多峰结构,并将其归因于喇曼散射中的合作效应.     

稀土配合物的喇曼散射和超喇曼散射效应

以可见光为激发光,观测了稀土配合物的喇曼散射和超瑞利、超喇曼散射光谱,简单论述了超瑞利和超喇曼散射的理论,对实验测出的谱线进行了认证与分析     

我国光散射研究的回顾与进展

本文简述了我国光散射研究发展历史，并对我国近几年物理研究中的喇曼光谱，化学、生物等学科中的喇曼光谱、布里渊散射、受激光散射，以及对光散射研究用的仪器设备的发展和现状等方面作了概略的介绍．     

准单模掺锗硅芯光纤的受激喇曼散射中的模竞争

本文报道了准单模掺锗硅芯光纤的受激喇曼散射中的模竞争实验研究。观察到了喇曼竞争现象和喇曼跳级现象。较详细分析了受激喇曼模的竞争。     

部分离化激光等离子体的受激喇曼散射不稳定性

由于部分离化激光等离子体中存在束缚电子，它可显著改变其参量不稳定性。本文分析了部分离化激光等离子体的受激喇曼散射的非线性色散关系，计算了钕玻璃倍频和三倍频激光受激喇曼散射的增长率，结果表明，前向受激喇曼散射显著增强，后向受激喇曼散射影响不大。     

Raman effect in the x-ray region

This paper presents a brief review of x-ray Raman scattering and some of our calculations on Raman scattered line shapes from light elements. We summarise the history of the Raman process in the x-ray region and present a detailed theory of the Raman scattering from an atomic many-electron system. Actual calculations of the Raman cross-section using this theory in single-particle approximation are given. The process of internal resonance Raman scattering is also discussed in the same formulation. The Raman cross-section is compared with the cross-sections of other x-ray scattering processes.     

Theoretical investigation on the pumping effect of stimulated Brillouin scattering on stimulated Raman scattering in water

The pumping effect of stimulated Brillouin scattering on stimulated Raman scattering is investigated theoretically through the coupled wave equations of stimulated Brillouin scattering and stimulated Raman scattering. The numerical simulations are in agreement with the experimental results. They indicate that the backward stimulated Raman scattering is excited and amplified collectively by both pump laser and stimulated Brillouin scattering.     

Double resonance Raman scattering of second-order Raman modes from an individual graphite whisker

Resonant Raman scattering of second-order Raman modes from an individual graphite whisker synthesized by a high-temperature heat-treatment method at a special pressure was discussed here. The dependence of phonon frequencies on the incoming laser light and the frequency difference between Stokes and anti-Stokes scattering show their origin from double resonance Raman scattering. Our results show that all the experimental results of second-order Raman modes in graphite whiskers, such as the excitation-energy dependence on the mode frequency, the frequency shift between a second-order Raman mode and its fundamentals, and the frequency discrepancy between Stokes and anti-Stokes components of a second-order Raman mode can be well understood by double resonance Raman scattering.     

The Raman effect in crystals

A review is given of progress in the theoretical and experimental study of the Raman effect in crystals during the past ten years. Attention is given to the theory of those properties of long-wavelength lattice vibrations in both cubic and uniaxial crystals which can be studied by Raman scattering. In particular the phenomena observed in the Raman scattering from crystals which lack a centre of inversion are related to the theory. The angular variations of the scattering by any type of lattice vibration in a crystal having any symmetry can be easily calculated using a complete tabulation of the Raman tensor. Recent measurements of first-order lattice vibration spectra are listed. A discussion of Brillouin scattering is included. The relation of second-order Raman spectra to critical points in the lattice vibration density of states is discussed, and measurements of the second-order spectra of diamond and the alkali halides are reviewed. The theory and experimental results for Raman scattering by electronic levels of ions in crystals are examined, and proposals for Raman scattering by spin waves, electronic excitations across the superconductive gap and by plasmons are collected together. Finally, the prospects for applying lasers as sources for Raman spectroscopy are discussed, and progress in the new technique of stimulated Raman scattering is reviewed.     

Electric field modulated Raman scattering in CdS

We have observed electric field modulated Raman scattering by A₁ LO phonons in CdS. The field induced scattering is observed with a geometry in which Raman scattering by A₁ LO phonons is normally allowed. The interference of the field induced and allowed terms in the transition susceptibility leads to a modulated Raman scattering intensity proportional to the applied field. This is contrasted with data previously reported on field induced Raman scattering by E₁ LO phonons in a configuration in which the Raman scattering is normally forbidden and in which there is no interference between linear wavevector dependent and field induced terms in the transition susceptibility. Electric field effects on Raman scattering by TO phonons and by 2 LO phonons is also discussed.     

The Raman effect in crystals

A review is given of progress in the theoretical and experimental study of the Raman effect in crystals during the past ten years. Attention is given to the theory of those properties of long-wavelength lattice vibrations in both cubic and uniaxial crystals which can be studied by Raman scattering. In particular the phenomena observed in the Raman scattering from crystals which lack a centre of inversion are related to the theory. The angular variations of the scattering by any type of lattice vibration in a crystal having any symmetry can be easily calculated using a complete tabulation of the Raman tensor. Recent measurements of first-order lattice vibration spectra are listed. A discussion of Brillouin scattering is included. The relation of second-order Raman spectra to critical points in the lattice vibration density of states is discussed, and measurements of the second-order spectra of diamond and the alkali halides are reviewed.

The theory and experimental results for Raman scattering by electronic levels of ions in crystals are examined, and proposals for Raman scattering by spin waves, electronic excitations across the superconductive gap and by plasmons are collected together.

Finally, the prospects for applying lasers as sources for Raman spectroscopy are discussed, and progress in the new technique of stimulated Raman scattering is reviewed.     

TiN镀层的一级和二级Raman散射

我们观测到了TiN镀层的一级和二级Raman散射,初步研究了TiN镀层的沉积参数和镀层性质对Raman谱的影响。结果表明TiN镀层的Raman散射不同于体材料氮化钛的Raman散射,特别是在二级Raman散射部分。     

Analysis and simulation of single-frequency Raman fiber amplifiers

High power operation of single-frequency Raman fiber amplifiers is usually limited by the onset of stimulated Brillouin scattering. A theoretical investigation on single-frequency Raman fiber amplifier limited by stimulated Brillouin scattering is presented in this paper, based on the intensity equations combining stimulated Brillouin scattering and stimulated Raman scattering. A combination of methods is proposed to increase the output power of single-frequency Raman fiber amplifier. These methods include applying a suitable pump scheme according to the fiber length and seed signal power, using short gain fibers, utilizing a multiple-stage scheme and providing suppression of stimulated Brillouin scattering.     

First and second order Raman scattering in transition metal compounds

First and second order Raman scattering was observed in NbC and ZrN. The scattering spectra differ greatly in the two materials. The position of the Raman peaks shows satisfactory agreement with high values of the phonon density obtained from neutron scattering data. In addition to previous results second order Raman scattering has also been found in TiN.