Vibrational states of H<Subscript>2</Subscript>O in beryl: physical aspects     

Boris Kolesov 《Physics and Chemistry of Minerals》2008,35(5):271-278

Single-crystal polarized Raman spectra (3,000–4,000 cm⁻¹ at 3 ≤ T ≤ 300 K) were measured for synthetic alkali-free and natural beryl, Be₂Al₃Si₆O₁₈·xH₂O, to determine the behavior of H₂O molecules of both Type I and Type II in the cavities. At low temperature, the H₂O molecules of Type I displace from the center of cavity and give rise to very weak hydrogen bonding with the host lattice. The H₂O Type I translational motion is characterized by substantial anharmonicity and looks like a motion of “a particle in the box” with a frequency of 6.3 cm⁻¹. Water Type II is characterized by a free rotation with respect to the C ₂ molecule axis, and it makes possible the water nuclear isomers (i.e. ortho- and para-) to be observed at low temperature.

Boris KolesovEmail:

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High-pressure Raman spectroscopic study of Co- and Ni-olivines     

C. C. Lin 《Physics and Chemistry of Minerals》2001,28(4):249-257

 The Raman spectra of synthetic α-Co₂SiO₄ and α-Ni₂SiO₄ olivines have been studied at room temperature and various pressures. All the Raman frequencies of the two olivines increase with increasing pressure, and most of the frequency–pressure plots obtained under both quasi- and nonhydrostatic conditions are nonlinear. It has been found that the average pressure derivative of Raman frequencies of the lattice modes in both Co- and Ni-olivines is smaller than that of the internal modes of SiO₄, indicating that the distortion of SiO₄ tetrahedra under static compression may be more severe than that of MO₆ octahedra. In addition, four new Raman bands were observed in Ni-olivine under nonhydrostatic compression and above 30 GPa. This result suggests that a new phase of Ni-olivine should be formed at 30 GPa or amorphization may occur at still higher pressure. Received: 11 July 2000 / Accepted: 19 December 2000  相似文献   

Raman spectroscopic study of hydrous wadsleyite (β-Mg2SiO4) to 50 GPa     

A. K. Kleppe  A. P. Jephcoat  H. Olijnyk  A. E. Slesinger  S. C. Kohn  B. J. Wood 《Physics and Chemistry of Minerals》2001,28(4):232-241

 Raman spectra of hydrous β-Mg₂SiO₄ (1.65 wt% H₂O) have been measured in a diamond-anvil cell with helium as a pressure-transmitting medium at room temperature to 50 GPa. We observe three OH-stretching modes, a doublet with components at 3329 and 3373 cm⁻¹, which decrease linearly with pressure, and a single mode at 3586 cm⁻¹, which remains nearly constant up to 24 GPa before decreasing at higher pressures. Assessment of the mode frequencies and their pressure dependence, together with previous results from X-ray and IR data, are consistent with protonation of the O1 site in agreement with previous studies. Strict assignment of Raman activity awaits detailed structural models. The nature of the protonation in wadsleyite may require more specific experimental probes for full solution of the hydrogen-site problem. Received: 18 July 2000 / Accepted: 22 November 2000  相似文献   

含金黄铁矿的拉曼光谱特征及其找矿意义初探   总被引：1，自引：0，他引：1       下载免费PDF全文

贾建业  潘兆橹 《地球科学》1997,22(6):575-578

黄铁矿的拉曼光谱特征长期被人们所忽视，经研究发现含金性不同的黄铁矿，其拉曼光谱特征存在诸多显著差异，其中尤以拉曼散射强度和相干度反应最敏感，反之，利用这些差异就可以对金矿床的含金性作出评价，此外，还对含金黄铁矿拉曼光谱产生的差异进行了理论剖析。  相似文献   

广东河台云西金矿床石英的拉曼光谱特征及其对含金性的评价   总被引：1，自引：0，他引：1  

陈伟  胡伦积 《矿物学报》1990,10(2):180-185

本文对广东河台云西金矿的石英进行了拉曼光谱研究。结果表明,含金石英与不含金石英的拉曼光谱有着本质的差异。作者通过量子理论的研究,对其差异进行了剖析,发现这种差异与它们之间成分、组构、形成温度的差异紧密联系。因此,作者得出结论:石英的拉曼光谱可以用于评价其含金性。  相似文献   

河南嵩县七亩地沟金矿床成矿流体来源及演化——来自矿床地质和流体包裹体的证据     

李新培  陈良  王琦崧  王文博  李雷  苏蔷薇 《矿床地质》2016,35(2):283-299

河南省嵩县七亩地沟金矿床位于华北克拉通南缘的熊耳山地区。矿床赋存在中元古代熊耳群中酸性火山岩中,矿体严格受构造断裂带控制,主要呈脉状产出,矿石以石英脉型占主导,少量蚀变岩型;主要矿石矿物为黄铁矿、少量方铅矿、闪锌矿、黄铜矿等。围岩蚀变以硅化、绢云母化、绿泥石化和碳酸盐化为主。成矿过程从早到晚可分为3个阶段:石英-黄铁矿阶段、黄铁矿-石英-多金属硫化物阶段和石英-方解石阶段。不同成矿阶段的石英和/或方解石中广泛发育流体包裹体。早阶段和中阶段石英中CO_2型流体包裹体、NaCl-H_2O型流体包裹体、含子矿物流体包裹体均有发育,晚阶段方解石中主要发育NaCl-H_2O型流体包裹体。从早阶段到晚阶段,流体包裹体均一温度分别为254~397℃、221~397℃、162~237℃,盐度w(NaCleq)从早阶段的3.52%~21.88%和34.95%~45.33%双峰值,经中阶段的0.42%~13.83%和29.11%~42.48%双峰值,到晚阶段w(NaCleq)为0.35%~5.86%。CO_2型包裹体估算的早阶段和中阶段捕获压力为93~199 MPa和47~169 MPa,晚阶段NaCl-H_2O型包裹体估算的捕获压力为28~64 MPa,相应的成矿深度为3.4~7.2 km、1.7~6.2 km和2.9~6.5 km,指示成矿发生在地壳隆升过程中,区域应力场由挤压向伸展转变。流体沸腾作用是导致硫化物和金等成矿物质快速沉淀的主要机制,通过沸腾和大气降水的混合,成矿流体系统由富CO_2向贫CO_2流体演化,由变质流体向大气降水演化。  相似文献   

Natural weathering of slags from primary Pb–Zn smelting as evidenced by Raman microspectroscopy     

《Applied Geochemistry》2016

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Evaluating the Effects of Autofluorescence during Raman Hyperspectral Imaging          下载免费PDF全文

Julienne R. Emry  Alison Olcott Marshall  Craig P. Marshall 《Geostandards and Geoanalytical Research》2016,40(1):29-47

Raman hyperspectral imaging is becoming a popular technique to analyse geological materials. Autofluorescence can affect the quality of the spectra that comprise hyperspectral data sets. Few studies have addressed potential misinterpretation of Raman images from hyperspectral data sets affected by autofluorescence. Additionally, little work has been done to develop methods for identifying the spatial distribution of spectra affected by autofluorescence. This study illustrates how autofluorescence may lead to misinterpretation of the distribution of materials based on intensity at a point images. A method is proposed utilising signal to axis analysis to create images that identify regions affected by autofluorescence. Post‐processing baseline correction is often used to address autofluorescence, and most software programs utilise a form of partial least squares regression modelling based on a subjective choice of polynomial order. This study shows that an inappropriate choice of polynomial order can introduce error, which may lead to misinterpretation of Raman images. A signal to axis analysis method is proposed to statistically compare seemingly ‘appropriate’ baseline correction trials. Although post‐processing of hyperspectral data sets and creating Raman images seem simple, data quality issues such as autofluorescence must be considered. If baseline correction is deemed necessary, it should be addressed as an experiment involving statistical comparison.  相似文献   

基于光学技术的水下气泡探测实验研究   总被引：1，自引：1，他引：0  

秦华伟  陶辰超  蔡真  范相会 《海洋科学》2016,40(6):119-125

热液/冷泉溢出含有硫化氢、甲烷、二氧化碳等化学成分的气泡。实验室模拟海底热液/冷泉资源溢出气泡环境搭建了实验平台,以甲烷气体为实验气体,在黑暗环境下用高速光电探测器对气泡后向散射光进行接收,用拉曼光谱仪实现甲烷气体气泡后向散射光的拉曼检测,并与计算拉曼光谱比较。由结果可知激光拉曼光谱可以探测到气泡后向散射光,并识别气泡中含有的气体成分。通过探测气泡成分,从而判定这些气泡是否来自海底热液/冷泉等甲烷资源溢出。这样的探测方式,探测准确率高,缓解探测深度,同时避免探测设备直接与海底资源直接接触而造成的寿命缩减,为将来的海洋探测与实际应用打下了良好的基础。  相似文献   

脉冲内拉曼散射所致啁啾的研究     

时延梅  王晶 《中国海洋大学学报(自然科学版)》2006,36(1):49-52

探究孤子自频移现象,从啁啾的角度来解释其产生的原因。运用数学求解及数值模拟方法,通过MATLAB编程画出了啁啾演变图,据此来研究自频移现象。研究结果表明,在高阶非线性效应中,脉冲内拉曼散射、色散和自相位调制共同所致的啁啾,与无拉曼散射效应时产生的啁啾相比,发生一系列新的变化:啁啾的中心发生漂移且图形的前后沿不对称,即负啁啾的峰值的绝对值大于正啁啾的峰值,这说明了脉冲频谱“红移”的谱峰变宽,或者说频谱移向了长波长方向—即人们所说的孤子自频移现象。  相似文献