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研究了近共振增强的四能级系统有机染料溶液中简并的四波混频后向反射波及前向波的位相复共轭特性。用有效长度为5mm,浓度为2.5×10~(-5)mol的叶录素A甲醇溶液作介质,当调QNd:YAG倍频泵浦光的能量为8mj时,非线性反射率为22%。 对于若丹明6G酒精溶液,在相同条件下的反射率为10%。用象差板检证了位相复共轭特性。用调QNd:YAG激光辐射作泵浦源,研究了若丹明6G酒精溶液双光子共振增强的简并的四波混频作用。当介质浓度为10~(-4)克分子,有效长度为5mm,泵浦光能量为70mj时,非线性反射率达14%。测量了非线性反射率与介质浓度及入射物波与后向反射波的强度的关系曲线。理论分析了四波混频前向波的位相复共轭特性,用调QNd:YAG倍频激光作泵浦源,若丹明6G酒精溶液作介质,实验上证实了理论的预言。另外,把四重简并的四波混频推广到二重简并的情况。用若丹明6G酒精溶液作介质,实现了由6300A到5320A的象转换。用9740有机染料二氯乙烷饱和吸收溶液作介质,实现了1.06μm到5320A的象转换。当介质长度为5mm,泵浦光束的能量为5mj时,后者的转换效率为25%。理论分析表明,用对红外近共振吸收,而对可见辐射是透明的介质可以实现高效率的红外象转换。这种红外象转换的方法还具有实时、快响应等优点。 相似文献
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在高压低温(77 K)条件下,利用红宝石荧光测压方法,系统地研究了金刚石对顶砧装置中固态氩和4∶1甲醇-乙醇混合物的传压特性。通过测量不同位置上红宝石荧光R1线的频移,确定了样品室内的压力分布。实验结果表明:在0~16 GPa的压力范围内,固态氩介质中反映介质非均匀性程度的|Δp/p|<3%、σp/p<2%,均在室温静水压条件下所允许的范围之内。红宝石荧光R线除随压力变宽外,与常压的很相似,表明固态氩在高压低温条件下是良好的传压介质。与之相比,4∶1甲醇-乙醇介质在77 K低温下的传压特性明显差于固态氩,已不适合作传压介质。 相似文献
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近代物理学为研究材料在超高压力下的物理性质,地震学与地球物理学为模拟地壳深层的高压状态,研制了几千、几万甚至几十万大气压的高压设备.在三或四万大气压以下,选用液体作传压介质.例如,石油醚、异戊烷等轻质矿物油,煤油、汽油等一般矿物油,来源于动植物的甘油、甲基或乙基硅油等高分子合成油,都可作为传压介质. 我们在一万大气压下试用过石油醚和变压器油的混合液.石油醚是石油分馏得到的低分子烃的混合物,主要是含碳链为C5和C6的戊烷、己烷.石油醚的最大缺点是易挥发、有气味、有麻醉性. 也可将煤油和变压器油按一定比例混合.煤油是石… 相似文献
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高岭石具有良好的流动密封、固体传压及机械加工等物理性能,是传统传压密封介质原料叶蜡石的替代品。采用比纯高岭石更适合作为传压密封介质原料的某地高岭石矿物,经过配料、混料、装模、压制成型以及焙烧等工序,制成了高岭石-白云石质传压密封介质,并对其进行金刚石合成扩大试验。试验结果表明:高岭石-白云石质传压密封介质能够达到与叶蜡石质传压密封介质相当的效果;合成金刚石的单产为19 g,抗压强度不小于160 N的晶粒占32%,晶粒尺寸大于或等于0.30 mm的占82%,合成1 g金刚石的顶锤消耗小于0.5 g,合成过程稳定。 相似文献
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本文使用固态氩做传压介质,在自制的Mao-Bell型金刚石对顶砧装置中获得了90 GPa的准静水压。通过测量样品室内不同位置上红宝石荧光R1线的频移来确定压力分布。实验结果表明在80 GPa以下,样品室内不同位置上的压力与平均压力(p)的差Δp很小,最大的Δp/p不超过1.5%。在90 GPa时,红宝石的荧光R线与常压的很相似。这表明利用固态氩做传压介质可以获得接近100 GPa的准静水压。此外,对红宝石荧光光谱中位置在14 938 cm-1和14 431 cm-1两条谱线随压力的变化情况也作了讨论,并由此得出结论,14 938 cm-1这条线也可用来标定压力。 相似文献
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本文以NaCl为例,证实了在我们的状态方程体系中,不同温度的状态方程可以认为是在px坐标系中不同起点开始的同一状态方程。于是,可由室温状态方程和常压热膨胀的测量数据估计高温状态方程。 相似文献
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S. Assimopoulos K.P. Meletov G.A. Kourouklis I. Margiolaki S. Margadonna K. Prassides 《高压研究》2013,33(1):63-67
The pressure behavior of the intramolecular phonon modes of the fullerene C 84 and its structural stability have been studied for the first time by means of Raman spectroscopy and synchrotron X-ray diffraction at high pressure up to ~10 GPa. The volume of the cubic unit cell has been measured as a function of pressure. The experimental data fitted by the Murnaghan equation-of-state (EOS) gave K_{0}=19.5\pm 0.9\,\hbox{GPa} and K_{0}^{\prime}=16.4\pm 0.6 . The pressure coefficients and Grüneisen parameters of the intramolecular phonon modes of C 84 have been determined and compared with those of other fullerenes. The data obtained do not show any phase transition and the pressure behavior of the material is entirely reversible in the pressure region investigated. 相似文献
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猛炸药爆轰产物的状态可以用两相的强排斥-平动物态方程(简称为两相的排平物态方程)很好地描述。以爆轰产物分两段的等熵曲线为参考曲线的两相的排平(k, γ)物态方程,已经用于爆轰参数和强爆轰参数的理论估算,所得理论值与实验值符合得很好。为了更方便地估算爆温,有必要给出描述分子间相互作用的比内能项与压力项(分别简称为冷比内能与冷压)。参照描述分子间相互作用的Morse势和Mie势的排斥项,给出了带待定参数A、m、n和l的冷比能项和冷压项,这样的物态方程被称为两相的排平(A, m, n, l)物态方程。用TNT的{D, ρ0}实验数据组,确定了两相的排平(A, m, n, l)物态方程的参数n=1和l=1/3,因此,可将其简称为两相的排平(A, m)物态方程。它适用于所有的猛炸药的爆轰产物。用硝基甲烷的强爆轰参数{p, D, T}实验数据组对其所做的检验表明,两相的排平(A, m)物态方程是恰当的爆轰产物物态方程。 相似文献
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介绍和评论了金刚石压腔中进行高温高压实验时的压力标定方法及其应用条件。其中红宝石和石英压标具有较高的准确度和精度,但前者不适合于高温和含饱和水条件下的标定,且在较低压力下误差较大,后者可用于高温且含水体系的压力标定,但仅适于低于2.0 GPa时的压力标定。矿物状态方程是较可靠的方法,但不方便且受条件限制。采用水的状态方程进行压力标定,可以解决压腔中不允许有压标矿物的问题,但在实验过程中要求压腔的体积保持恒定。因此,在采用金刚石压腔进行高温高压实验时,应根据研究需要决定合适的压力标定方法,而且寻找新的压力标定方法仍是金刚石压腔高压实验的基础工作。 相似文献
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Equation of state for solids with considering cohesive energy and anharmonic effect and its application to MgO 下载免费PDF全文
A simple equation of state (EOS) in wide ranges of pressure and temperature is constructed within the Mie-Grüneisen-Debye framework. Instead of the popular Birch-Murnaghan and Vinet EOS, we employ a five-parameter cold energy expression to represent the static EOS term, which can correctly produce cohesive energy without any spurious oscillations in extreme compression and expansion region. We developed a Padé approximation-based analytic Debye quasiharmonic model with high accuracy which improves the performance of EOS in low temperature region. The anharmonic effect is taken into account by using a semi-empirical approach. Its reasonability is verified by the fact that the total thermal pressure tends to the lowest-order anharmonic expansion in the literature at low temperature, and tends to ideal-gas limitation at high temperature, which is physically correct. Besides, based on this approach, the anharmonic thermal pressure can be expressed in the Grüneisen form, which is convenient for applications. The proposed EOS is used to study the thermodynamic properties of MgO including static and shock compression conditions, and the results are very satisfactory as compared with the experimental data. 相似文献
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Experimental results on the attenuation of ultrasound in polar-polar liquid, that is, water-alcohol mixtures, by the method of streaming are presented. A comparative study of the results obtained by this method and those obtained by other methods has been made. Results of the present investigations agree well with those obtained by other workers. From the observed attenuation data, the bulk viscosity coefficients ‘b’ of the mixtures have been determined using Eckart's formalism on streaming.Satisfactory results could be obtained in the cases of water/methyl alcohol, and water/ethyl alcohol mixtures at all percentage compositions of mixtures but in the case of water/n-propyl alcohol satisfactory results could not be obtained at 5% to 40% mixture compositions. This observation bears the similarity with the cases of pure non-polar liquids. Here the observed results have been attempted to be explained, at least on the basis of relevant physical principles, in terms of dipole moment and dielectric constant. 相似文献
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Guy Lucazeau Olivier Le Bacq Alain Pasturel Pierre Bouvier Thierry Pagnier 《Journal of Raman spectroscopy : JRS》2011,42(3):452-460
Polarized Raman spectra of a single crystal of gadolinium molybdate [Gd2(MoO4)3] were obtained between 1 atm and 7 GPa. Using a mixture of alcohols as the pressure‐transmitting medium, YY, ZZ, XY components of scattering matrices were measured. The ZZ spectra were also obtained in argon. Five phase transitions and amorphization were identified. The first and second transitions are reversible, while amorphization is not. In alcohol, amorphization is observed above 6.5 GPa. With argon as the pressure‐transmitting medium, amorphization is progressive and begins above 3 GPa. The spectral changes with pressure affect the high wavenumber bands attributed to symmetric and antisymmetric MoO4 stretching modes as well as the very low wavenumber modes such as librations of the tetrahedra. This means that both short‐range and long‐range organizations of the tetrahedra are involved in these phase transitions. The amorphization mechanism and its dependence on the pressure‐transmitting medium are discussed, and the steric hindrance between polyhedra is believed to be the most relevant mechanism. The TO and LO low wavenumber modes of A1 symmetry, observed in the Y(ZZ)Y and Z(YY)Z geometries, respectively, below 50 cm−1, soften continuously through the first three phases when increasing pressure. The strong A2 mode observed in the Z(XY)Z spectra exhibits the same anomalous behavior by decreasing from 53 to 46 cm−1 at 2 GPa. The softening of these modes is related to the orientation change of tetrahedra observed by ab initio calculations when the volume of the cell is decreased. These orientation changes can explain the wavenumber decrease of the Mo O stretching modes above 2 GPa, which indicates an increase of Mo coordination. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Equation of state for solids considering cohesive energy and anharmonic effect and its application to MgO 下载免费PDF全文
A simple equation of state(EOS) in wide ranges of pressure and temperature is constructed within the MieGrneisen-Debye framework.Instead of the popular Birch-Murnaghan and Vinet EOS,we employ a five-parameter cold energy expression to represent the static EOS term,which can correctly produce cohesive energy without any spurious oscillations in the extreme compression and expansion regions.We developed a Pad’e approximation-based analytic Debye quasiharmonic model with high accuracy which improves the performance of EOS in the low temperature region.The anharmonic effect is taken into account by using a semi-empirical approach.Its reasonability is verified by the fact that the total thermal pressure tends to the lowest-order anharmonic expansion in the literature at low temperature,and tends to ideal-gas limitation at high temperature,which is physically correct.Besides,based on this approach,the anharmonic thermal pressure can be expressed in the Gru¨neisen form,which is convenient for applications.The proposed EOS is used to study the thermodynamic properties of MgO including static and shock compression conditions,and the results are very satisfactory as compared with the experimental data. 相似文献