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 共查询到18条相似文献,搜索用时 93 毫秒
1.
唐志列  林理忠 《光学学报》1993,13(6):57-563
用热弹性理论系统地分析了凝聚态物质的光声喇曼效应,分别导出了连续和脉冲激光泵浦下的光声喇曼信号表达式,并做了数值估算.  相似文献   

2.
光声喇曼光谱的理论分析   总被引:1,自引:0,他引:1       下载免费PDF全文
唐志列  司徒达  梁瑞生 《物理学报》1992,41(11):1789-1795
对光声喇曼光谱(PARS)作了系统的理论分析,分别导出固体和液体介质中的光声喇曼光谱的信号表达式,并进行了数值估算。 关键词:  相似文献   

3.
报道一种改进的受激喇曼光声光谱实验方法 (PhotoacousticRamanSpectroscopy ,PARS) ,该方法的主要特点是将两束激光以反向传播的方式重合 ,从而不仅克服了通常的实验方法 (两束激光通过双色镜片重合 )在测量小喇曼位移方面的限制 ,也使实验的操作更加简单 .在实验中 ,以CH4 分子为研究对象 ,一束波长为 5 3 2 .1nm的激光作为泵浦光 ,另一束可调谐激光作为探测光 (Stokes光 ) ,两束光相向作用于光声池内 ,在 62 5~ 64 2nm和 5 73~ 5 89nm得到了CH4 分子ν1 、ν2 和ν3模的PARS光谱 ,其结果与前人利用自发喇曼散射技术 (ORS)一致 ,其中喇曼活性较弱且喇曼位移较小的ν2 模的PARS光谱是新得到的  相似文献   

4.
陈慧挺  楼祺洪  董景星  陈万春 《光子学报》2006,35(10):1441-1444
橘黄色波段固体激光器在基于荧光探测的生物医学诊断和显示等众多方面有着广泛的实际应用. 报道了利用532 nm的Nd∶YAG倍频激光抽运外置喇曼腔内的硝酸钡晶体,获得高效率的599 nm橘黄色喇曼激光的实验结果.对外置喇曼腔实验装置和运转参量进行了优化,喇曼振荡腔由对二阶斯托克斯光有最优化反射率的腔镜构成,对实验中所得到的二阶斯托克斯喇曼激光脉宽压缩及出现双尖峰的现象进行了分析.当抽运光功率达到4.1 W时,获得二阶斯托克斯喇曼激光功率为710 mW,输出光中心波长为599.38 nm,半峰全宽(FWHM)为1.1 nm,激光器最大光光转换效率为17.5%,斜率效率为24.8%.  相似文献   

5.
光纤喇曼放大泵浦光与信号光的关联研究   总被引:1,自引:1,他引:0  
王涛  姚建铨  李喜福  郁道银  禹国俊  王鹏 《光子学报》2003,32(11):1321-1324
分析了信号光入射后可能发生的效应基于电磁场理论,综合光纤受激喇曼散射(SRS)效应、建立了光纤喇曼放大泵浦光与斯托克斯光、信号光的关联方程,给出了系统增益形成正反馈条件的表达式,结果表明:在光纤参量满足增益正反馈的条件下,当SRS增益对应于非饱和增益工作状态时入射信号光得到放大,SRS增益愈高则放大倍数愈高,并有区段上SRS增益相对低时其关联程度相对高.  相似文献   

6.
本文报道Ti扩散LiNbO_3光波导中四种直角配置的喇曼散射光谱。实验中,我们观测到了在这些配置下异常的喇曼光谱现象。这一现象可归结为光波导中入射光TE/TM模式的变换行为。  相似文献   

7.
本文主要研究表面极化声子的喇曼散射.在探测表面极化声子的衰减全反射方法以及喇曼散射方法的基础上,借鉴了Kretchmann配置的衰减全反射喇曼散射法,提出了Otto配置的衰减全反射喇曼散射法,并以CaF_2单晶体为样品做了一系列实验.同时,本文利用了能量守恒及平行于样品表面的能量守恒关系,利用了格林函数或响应函数所推出的表面极化声子的一般频散关系,理论上给出了CaF_2-空气表面极化声子的一个唯象的频散关系.实验上用特定设计制做的一个样品架对CaF_2样品测定了它与空气界面上的表面极化声子的频散关系,比较结果,理论与实验取得了比较令人满意的一致.  相似文献   

8.
光纤喇曼增益系数的简捷测量   总被引:7,自引:4,他引:3  
姜海明  王亚非 《光子学报》2004,33(6):666-668
基于小信号开关增益原理,采用抽运光-探测波法,利用SLD(超辐射激光二极管)作为宽带小信号探测光源,快速测量出了标准单模光纤(G.652)的频移为0.5~20 THz内的喇曼增益系数,测量结果和文献中已有的值基本吻合,所测得的光纤喇曼增益系数可用于光纤喇曼放大器的理论和实验研究,该方法同样可以对其他类型光纤的喇曼增益系数进行测量.  相似文献   

9.
本文采用Raman-Maxwell-Bloch方程,计算了宽频带聚焦泵浦准稳态受激电子喇曼散射的增益因子和能量转换效率.在计算中考虑了泵浦抽空、喇曼介质对泵浦光的吸收和喇曼介质的泡和效应.计算结果与XeCl激光在钡蒸汽中的受激喇曼散射实验基本上符合.  相似文献   

10.
抽运光谱宽度对喇曼光纤放大器的影响   总被引:2,自引:2,他引:0  
采用受激喇曼散射(SRS)耦合波理论分析了抽运光谱宽度对喇曼光纤放大器的影响, 指出当采用宽光谱作抽运光时会降低抽运效率. 同时, 文中还给出了抽运光谱宽度、抽运光功率和抽运效率间的变化规律曲线, 得出当传输光纤的有效截面积越小、喇曼增益系数越大、抽运光的入纤功率和光谱线宽度越大时, 光谱抽运效率越小的结论.  相似文献   

11.
Abstract

Photoacoustic Raman spectroscopy (PARS) [1] is a nonlinear spectroscopic technique based upon the selective population of a given energy state of a system by the process of coherent Raman amplification (stimulated Raman scattering). The necessary conditions for this process are: (1) the transition involving the initial and final energy levels must be Raman-active, i.e., the transitions must involve a change in the molecular polarizability; and (2) the frequency difference of the two incident laser beams must be adjusted to equal the frequency of this Raman-active transition. Since the occurrence of a Raman spectrum depends on a change in polarizability of the molecule and not on the presence of a transition dipole moment, Raman-active transitions can occur for molecules that have no infrared spectrum. This fact makes PARS a particularly attractive analytical technique for studying molecules which have no infrared spectrum The PARS technique was first demonstrated experimentally using  相似文献   

12.
液体的脉冲差分光声喇曼光谱   总被引:3,自引:2,他引:1  
唐志列  司徒达 《光学学报》1993,13(4):79-382
采用脉冲光声方法测量了各种有机和无机液体的受激喇曼光谱,探讨了影响这种光谱技术灵敏度的主要原因,即来自线性吸收信号的干扰,并进一步采用一种改进的方法——差分方法,消除了线性光声信号的影响,可以测量到比较弱的喇曼谱线以及浓度比较低的物质的喇曼光谱,并探讨了这种技术在痕量物质测量以及探测环境污染物质等领域中的应用前景.  相似文献   

13.
以气相甲烷分子ν1模Q支的拉曼光谱为例,采用拉曼诱导克尔效应谱(RIKES)进行峰形测量,并将其与同时测量的受激拉曼光声光谱(PARS)的峰形进行了比较.结果表明,在pump光和Stokes光均为线偏振的情况下,两者存在着差异;在拉曼共振峰的低频端,RIKES谱强度略高;而高频端则恰好相反.从信号产生机制出发,对此进行了合理解释. 关键词: 拉曼诱导克尔效应谱 受激拉曼光声光谱 峰形  相似文献   

14.
利用灵敏的光声拉曼光谱技术对气相二氧化碳分子在1240~1430 cm-1振动光谱的拉曼退偏比进行了测量. 通过测量并拟合光声拉曼信号强度随两束入射光偏振方向夹角的变化,得到了比文献报道中更为精确的退偏比数据.  相似文献   

15.
We consider stimulated Raman emission in solids, placed in a plane laser beam external to the cavity. The Hamiltonian of the system of phonons, electrons and electromagnetic fields is derived within the framework of a generalized adiabatic approximation for electrons and nuclei. It contains terms due to nonlinear interactions between electrons and phonons. Because the usual time-dependent perturbation theory cannot describe coherence effects properly we turn toHeisenberg's equations of motion for the operators of photons, phonons and electron excitations. In order to solve these equations in the steady state we apply an iteration procedure. We start with the light waves which give rise to electron transitions. The electrons such excited create phonons which then react on the electrons. Finally the electrons are coupled again to the lightfield. This procedure yields besides the usual wellknown Raman process two main processes occurring in stimulated Raman emission: a coupled two step Raman process and a parametric process. In the first one two phonons are involved. If the linewidth of phonons is comparable to the phonon frequencies the non-resonant parts of the above processes also become important. In solving the set of coupled equations for the light amplitudes, obtained from the iteration procedure, we only consider terms due to the first Stokes, the first anti-Stokes and the laser line. We then find frequency shifts of these lines due to the stimulated emission which are of the order of the linewidth of photons if this linewidth is very much smaller than that of phonons as it is the case in solids. This means that the coupled two step Raman process is dominant, in good agreement with measurements ofChiao andStoicheff in calcite.  相似文献   

16.
Clathrate hydrates are particular solids that planetologists study in detail because those solids may be present in several bodies of the solar system, such as Mars, comets, and the icy satellites. The solids are formed by solid H2O, like common water ice, but adopt open structures with cavities containing gas molecules. Clathrate hydrates are usually stable at relatively low temperature and high pressure, which are the typical conditions present inside these planetary objects. Their interest for astrobiology is that they represent potential sources of liquid water and gases when they decompose. The present work is focused on the crystallization of clathrates in Europa's (icy satellite of Jupiter) interior conditions. We postulate that clathrate hydrates may play an important role in its crust mineralogy and that it can explain some features of the satellite's surface due to their formation/destabilization. An in situ kinetic study by Raman Spectroscopy of the clathrate formation from salty solutions was performed in our laboratory. The chemical composition that we used mimics those obtained from Europa's surface during the Galileo mission. An effect of the salting-out process in the solution was monitored through the clathrate formational path. Our results demonstrate that this process may have geological consequences on Europa and confirm the suitability of Raman spectroscopy for planetary detection of clathrate hydrates and other ices.  相似文献   

17.
The width of phonon lines in the Raman spectra of ideal isotopically pure solids is determined by inelastic scattering processes. In solids that contain a mixture of different isotopes of one atomic constituent, elastic scattering due to isotopic mass disorder opens up decay channels that result in additional line broadening. We use different polytypes of SiC with an associated number of Raman active modes in order to experimentally validate the proportionality between linewidth and phonon density of states predicted by a simple elastic scattering theory.  相似文献   

18.
The deformation of chemical bonds in polymer molecules of surface layers of samples, boundary layers between supramolecular aggregates, and boundary layers between polymers and solids in polymer composites is investigated using IR and Raman spectroscopy. It is found that the chemical bonds are elongated on a free surface and in boundary layers between supramolecular aggregates. By contrast, the chemical bonds are contracted in boundary layers between polymers and solids. The concentration and the strain of excited chemical bonds (strained to approximately a theoretical ultimate elongation) are increased on the free surface and in the boundary layers between supramolecular aggregates, whereas the concentration and the strain of excited chemical bonds in the boundary layers between polymers and solids are decreased. These effects are explained by the changes in the atomic vibrations in the surface and boundary layers.  相似文献   

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