共查询到18条相似文献,搜索用时 312 毫秒
1.
在单次冲击压缩实验中,借助新建的瞬态拉曼光谱技术实现了对液态硝基甲烷冲击拉曼光谱的原位观测,来探究该样品分子在冲击波作用下的结构稳定性.实验发现,在10.6 GPa的冲击加载下硝基甲烷的拉曼特征峰仅发生了蓝移和展宽,而在观测波段未发现化学变化产生的迹象.这一结果否定了文献所报道的硝基甲烷在6 GPa~8.5 GPa的单次冲击压力区间内发生了化学反应的推论,同时也证实了在10.6GPa的冲击压力下硝基甲烷分子在约为516 ns的压缩时间内能够保持其结构的稳定. 相似文献
2.
在单次冲击压缩实验中,借助新建的瞬态拉曼光谱技术实现了对液态硝基甲烷冲击拉曼光谱的原位观测,来探究该样品分子在冲击波作用下的结构稳定性。实验发现,在10.6GPa的冲击加载下硝基甲烷的拉曼特征峰仅发生了蓝移和展宽,而在观测波段未发现化学变化产生的迹象。这一结果否定了文献所报道的硝基甲烷在6GPa~8.5GPa的单次冲击压力区间内发生了化学反应的推论,同时也证实了在10.6GPa的冲击压力下硝基甲烷分子在约为516ns的压缩时间内能够保持其结构的稳定。 相似文献
3.
显微激光拉曼光谱原位观测甲烷水合物生成与分解的微观过程 总被引:1,自引:0,他引:1
采用显微激光拉曼光谱技术对高压透明毛细管中甲烷水合物的生成与分解的微观过程进行了原位观测,初步探讨了甲烷水合物笼型结构的变化规律.结果表明,甲烷水合物在生成过程中,甲烷分子的拉曼峰(2 917 cm-1)逐渐分裂为两个峰(2 905和2 915 cm-1),表明溶解态甲烷分子从单一的化学环境进入了两个有差异的化学环境中... 相似文献
4.
5.
甲烷水合物在化学、能源和环境科学等领域中都具有重要作用. 本文采用普适的基于能量的分块(GEBF)方法计算了多种甲烷水合簇的结合能和拉曼光谱. 首先使用这些甲烷水合簇的在显相关耦合簇[CCSD(T)(F12*)]水平下得到的GEBF结合能,评估了一系列密度泛函计算的结果. 计算结果表明B3PW91-D3和B97D泛函表现最佳,与GEBF-CCSD(T)(F12*)基准相比的平均绝对误差分别仅为0.27和0.47 kcal/mol. 然后用GEBF-B3PW91-D3方法计算得到了单、双笼甲烷水合簇的结构和拉曼光谱,得到的甲烷C-H键伸缩拉曼振动峰与实验值的偏差小于3 cm-1,说明B3PW91-D3泛函可以很好地重现实验结果. 随着水笼尺寸的增加. 甲烷C-H键伸缩拉曼峰发生红移,该现象与实验中提出的“松笼-紧笼”模型吻合. 此外,甲烷分子邻近环境(水笼)的改变对拉曼光谱的影响很小,环境从单笼变为双笼导致C-H键伸缩拉曼振动峰的蓝移不超过3 cm-1. 甲烷水合簇的理论拉曼光谱与实验拉曼光谱结合可以用来研究海底或星际冰体内部的甲烷水合物的结构. 结合B3PW91-D3或B97D泛函和机器学习模型,可以进一步应用分子动力学模拟研究甲烷水合物的成核/生长机制和相变过程. 相似文献
6.
7.
应用便携式拉曼光谱仪,采集了四种醛类分子(GnH2nO,n=1,2,3,4)的拉曼光谱,并通过量子化学中密度泛函理论(DFT)对四种醛类分子进行了分子模型构建和理论拉曼光谱模拟计算.通过实验拉曼光谱和DFT模拟计算结果的对比,对四种醛类分子的特征振动峰进行了指认.同时对四种醛类分子的实验光谱进行了分析比较.应用便携式拉... 相似文献
8.
基于相干反斯托克斯拉曼散射(CARS)光谱技术机理,针对甲醇制烯烃(MTO)产物中多种组分烃类的探测需求,搭建了一套扫描式窄带CARS光谱实验装置。采用该装置对甲烷,乙烷,乙烯,丙烯分别进行CARS光谱扫描,获得了各分子的特征拉曼谱;并在相同实验条件下进行比对试验,得到不同分子特征峰处的CARS信号强度与目标气体浓度及其他背景气体之间的关系。通过建立简化模型对不同分子的CARS信号特征峰强度信息进行解析,提出了一种分时窄带CARS光谱探测多种拉曼活性气体浓度的方法,用于快速在线分析催化化工等领域中各类流体的组分。利用这种方法探测了甲烷,乙烯,丙烯的浓度,将实验误差控制在9%以内。 相似文献
9.
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
10.
11.
R. Ouillon J.‐P. Pinan‐Lucarr B. Canny P. Pruzan P. Ranson 《Journal of Raman spectroscopy : JRS》2008,39(3):354-362
Raman and infrared spectra of internal phonons in solid nitromethane‐h3 and ‐d3 were measured as a function of pressure in the range 0–40 GPa at room temperature. Experiments were performed in diamond anvil cells. The evolution of the splitting of the various modes in condition of nearly hydrostatic compression supports the maintenance of the P212121 crystal structure until the material chemically transforms into an amorphous phase. The observed pressure‐induced shifts of vibrational wavenumbers are consistent with computations recently reported in the literature. Infrared and Raman spectroscopies deliver complementary information on the internal modes behaviour. The continuous evolution of the infrared band shapes suggests a weak molecular distortion during the compression process. The strong modifications that are observed in the Raman bands of the nitro group are attributed to polarization effects arising from a rearrangement of the molecules inside the unit cell in the pressure range 10–12 GPa, a consequence of a close intermolecular O…H approach. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
12.
Abstract We have measured Raman spectra of metastable phases of Si and Ge prepared in a diamond anvil cell for pressures up to 12 GPa. For Si we observe eight Raman lines with mode Grüneisen parameters varying between -0.3 and 1.5. These lines can be assigned to the zone-center phonons of the cubic BC8-structure (Z = 8) by assuming a violation of Raman selection rules presumably due to disorder. In the case or Ge we observe two phases with different Raman spectra. The spectrum of the first phase is strikingly similar to that of BC8-Si. Below about 5 GPa this phase transforms into a second phase, which can be identified as Ge in the hexagonal diamond structure. 相似文献
13.
14.
J. Arvanitidis K. P. Meletov G. A. Kourouklis K. Papagelis A. Soldatov K. Prassides 《高压研究》2013,33(1-6):145-151
Abstract The effect of high hydrostatic pressure, up to 12GPa, on the intramolecular phonon frequencies and the material stability of the two-dimensional tetragonal Cm polymer has been studied by means of Raman spectroscopy in the spectral range of the radial intramolecular modes (200-800cm?1). A number of new Raman modes appear in the spectrum for pressures ~ 1.4 and ~ 5.0 GPa. The pressure coefficients for the majority of the phonon modes exhibit changes to lower values at P=4.0 GPa, which may be related to a structural modification of the 2D polymer to a more isotropic phase. The peculiarities observed in the Raman spectra are reversible and the material is stable in the pressure region investigated. 相似文献
15.
U.L.C. Hemamala D.V.S. Muthu A.M. Krogh Andersen L. Ouyang 《Solid State Communications》2007,141(12):680-684
The room-temperature Raman and infrared spectra of zirconium vanadate (ZrV 2O7) were observed up to pressures of 12 GPa and 5.7 GPa, respectively. The frequencies of the optically active modes at ambient pressure were calculated using direct methods and compared with experimental values. Average mode Grüneisen parameters were calculated for the Raman and infrared active modes. Changes in the spectra under pressure indicate a phase transition at ∼1.6 GPa, which is consistent with the previously observed α (cubic) to β (pseudo-tetragonal) phase transition, and changes in the spectra at ∼4 GPa are consistent with an irreversible transformation to an amorphous structure. 相似文献
16.
S. Loridant G. LucazeauT. Le Bihan 《Journal of Physics and Chemistry of Solids》2002,63(11):1983-1992
A high-pressure structural study of SrCeO3 has been performed at room temperature by Raman spectroscopy and X-ray diffraction up to 32 and 45 GPa, respectively. A first-order reversible phase transition is observed at about 12 GPa in both techniques. A second weak structural change, taking place between 18 and 25 GPa, can be suspected from Raman data. The increase in the number of Raman bands and diffraction lines is an indication that the symmetry is lowered and the compound does not evolve towards the ideal cubic perovskite structure. A Rietveld analysis of X-ray data was performed for the low-pressure phase and the atomic positions and the cell lattice parameters variations are reported in this paper. The volume compressibility derived from Raman modes (5.6×10−12 Pa−1), involving mainly bond-stretching for each type of polyhedron, is found to be close to the one obtained from volume cell variations measured by X-ray diffraction (7.9×10−12 Pa−1). 相似文献
17.
Zhao Bei-jingLiu Fu-shengWang Wen-pengZhang Ning-chaoFeng Li-pengZhang Ming-jianXue Xue-dong 《光谱学与光谱分析》2013,(10):2603-2606
The present paper reports the high resolution transient Raman laser testing technology under two-stage light gas-gun loading experiment, and its application to studying the Raman spectroscopy of shocked benzene. In the experiments, the frequency shift of C-C stretching vibration (992 cm(-1)) and C H stretching vibration peak (3 061 cm(-1)) in the low pressure section (less than 8 GPa) varies linearly with the pressure, and the results agree well with reported data in the literature. The structural changes in liquid benzene about 13 GPa were clarified firstly by the Raman spectral technique; the experimental results show that at a pressure of 9.7 GPa, the structural change of liquid benzene has taken place, not reported in the literature about 13 GPa. But the composition in the production is not clear. The measurement system provides an effective means to study the microstructure changes of transparent and translucent material under dynamic loading experiment. 相似文献
18.
Fangfei Li Defang Duan Min Li Chunli Ma Qiliang Cui Tian Cui Qiang Zhou Xiaodong Li Yanchun Li Jing Liu Guangtian Zou 《Journal of Raman spectroscopy : JRS》2012,43(4):526-531
Single crystal Brillouin and Raman scattering measurements on NH3 in a diamond anvil cell have been performed under pressures up to 26 GPa at room temperature. The pressure dependencies of acoustic velocity, adiabatic elastic constants, and bulk moduli of ammonia from liquid to solid III and solid IV phase have been determined. All the nine elastic constants in orthorhombic structure phase IV were presented for the first time, each elastic constant grows monotonously with pressure and a crossover of the off‐diagonal moduli C12 and C13 was observed at around 12 GPa because of their different pressure derivative values. We also performed ab initio simulations to calculate the bulk elastic moduli for orthorhombic ammonia, the calculated bulk moduli agree well with experimental results. In Raman spectra the very weak bending modes ν2 and ν4 for orthorhombic ammonia are both observed at room temperature, a transition point near 12 GPa is also found from the pressure evolution of the Raman bands. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献