首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
    
The arsenite mineral finnemanite Pb5(As3+ O3)3Cl has been studied by Raman spectroscopy. The most intense Raman band at 871 cm−1 is assigned to the ν1(AsO3)3− symmetric stretching vibration. Three Raman bands at 898, 908 and 947 cm−1 are assigned to the ν3(AsO3)3− antisymmetric stretching vibration. The observation of multiple antisymmetric stretching vibrations suggest that the (AsO3)3− units are not equivalent in the molecular structure of finnemanite. Two Raman bands at 383 and 399 cm−1are assigned to the ν2(AsO3)3− bending modes. Density functional theory enabled calculation of the position of AsO32− symmetric stretching mode at 839 cm−1, the antisymmetric stretching mode at 813 cm−1 and the deformation mode at 449 cm−1. Raman bands are observed at 115, 145, 162, 176, 192, 216 and 234 cm−1 as well. The two most intense bands are observed at 176 and 192 cm−1. These bands are assigned to PbCl stretching vibrations and result from transverse/longitudinal splitting. The bands at 145 and 162 cm−1 may be assigned to Cl Pb Cl bending modes. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

2.
    
The oriented single‐crystal Raman spectrum of leiteite has been obtained and the spectra related to the structure of the mineral. The intensities of the observed bands vary according to orientation, allowing them to be assigned to either Ag or Bg modes. Ag bands are generally the most intense in the CAAC spectrum, followed by ACCA, CBBC, and ABBA whereas Bg bands are generally the most intense in the CBAC followed by ABCA. The CAAC and ACCA spectra are identical, as are those obtained in the CBBC and ABBA orientations. Both cross‐polarised spectra are identical. Band assignments were made with respect to bridging and non‐bridging As O bonds. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

3.
    
The mixed anion mineral dixenite has been studied by Raman spectroscopy, complemented with infrared spectroscopy. The Raman spectrum of dixenite shows bands at 839 and 813 cm−1 assigned to the (AsO3)3− symmetric and antisymmetric stretching modes. The most intense Raman band of dixenite is the band at 526 cm−1 and is assigned to the ν2 AsO33− bending mode. DFT calculations enabled the calculation of the position of AsO22− symmetric stretching mode at 839 cm−1, the antisymmetric stretching mode at 813 cm−1, and the deformation mode at 449 cm−1. The Raman bands at 1026 and 1057 cm−1 are assigned to the SiO42− symmetric stretching vibrations and those at 1349 and 1386 cm−1 to the SiO42− antisymmetric stretching vibrations. Both Raman and infrared spectra indicate the presence of water in the structure of dixenite. This brings into question the commonly accepted formula of dixenite as CuMn2+14Fe3+(AsO3)5(SiO4)2(AsO4)(OH)6. The formula may be better written as CuMn2+14Fe3+(AsO3)5(SiO4)2(AsO4)(OH)6·xH2O. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

4.
    
The removal of arsenate anions from aqueous media, sediments and wasted soils is of environmental significance. The reaction of gypsum with the arsenate anion results in pharmacolite mineral formation, together with related minerals. Raman and infrared (IR) spectroscopy have been used to study the mineral pharmacolite Ca(AsO3OH)· 2H2O. The mineral is characterised by an intense Raman band at 865 cm−1 assigned to the ν1 (AsO3)2− symmetric stretching mode. The equivalent IR band is found at 864 cm−1. The low‐intensity Raman bands in the range from 844 to 886 cm−1 provide evidence for ν3 (AsO3) antisymmetric stretching vibrations. A series of overlapping bands in the 300‐450 cm−1 region are attributed to ν2 and ν4 (AsO3) bending modes. Prominent Raman bands at around 3187 cm−1 are assigned to the OH stretching vibrations of hydrogen‐bonded water molecules and the two sharp bands at 3425 and 3526 cm−1 to the OH stretching vibrations of only weakly hydrogen‐bonded hydroxyls in (AsO3OH)2− units. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

5.
    
The mixed anion mineral chalcophyllite Cu18Al2(AsO4)4(SO4)3(OH)24·36H2O has been studied by using Raman and infrared spectroscopies. Characteristic bands associated with arsenate, sulfate and hydroxyl units are identified. Broad bands in the OH stretching region are observed and are resolved into component bands. Estimates of hydrogen bond distances were made using a Libowitzky function. Both short and long hydrogen bonds were identified. Two intense bands at 841 and ∼814 cm−1 are assigned to the ν1 (AsO4)3− symmetric stretching and ν3 (AsO4)3− antisymmetric stretching modes. The comparatively sharp band at 980 cm−1 is assigned to the ν1 (SO4)2− symmetric stretching mode, and a broad spectral profile centred upon 1100 cm−1 is attributed to the ν3 (SO4)2− antisymmetric stretching mode. A comparison of the Raman spectra is made with other arsenate‐bearing minerals such as carminite, clinotyrolite, kankite, tilasite and pharmacosiderite. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

6.
    
  相似文献   

7.
    
Hydrotalcites have been synthesised using solutions of three different pH values to assess the effect of pH on the uptake of arsenate and vanadate. The ability of these hydrotalcites to remove vanadate and arsenate from solution has been determined by inductively coupled optical emission spectroscopy. Raman spectroscopy was used to monitor changes in the anionic species for hydrotalcites synthesised at different pH values. The results show a reduction in the concentration of arsenate and vanadate anions that are removed in extremely alkaline solutions. Hydrotalcites containing arsenate and vanadate are stable in solutions up to pH 10. Exposure of these hydrotalcites to higher pH values results in the removal of large percentages of arsenate and vanadate from the hydrotalcite interlayer. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

8.
    
Raman spectrum of burgessite, Co2(H2O)4[AsO3OH]2· H2O, was studied, interpreted and compared with its infrared spectrum. The stretching and bending vibrations of (AsO3) and As‐OH units, as well as the stretching, bending and libration modes of water molecules and hydroxyl ions were assigned. The range of O H···O hydrogen bond lengths was inferred from the Raman and infrared spectra of burgessite. The presence of (AsO3OH)2− units in the crystal structure of burgessite was proved, which is in agreement with its recently solved crystal structure. Raman and infrared spectra of erythrite inferred from the RRUFF database are used for comparison. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

9.
    
Raman spectra of natrouranospinite complemented with infrared spectra were studied and related to the structure of the mineral. Observed bands were assigned to the stretching and bending vibrations of (UO2)2+ and (AsO4)3− units and of water molecules. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

10.
    
Raman spectra of metauranospinite Ca[(UO2)(AsO4)]2·8H2O complemented with infrared spectra were studied. Observed bands were assigned to the stretching and bending vibrations of (UO2)2+ and (AsO4)3− units and of water molecules. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

11.
    
Raman spectra of two well‐defined types of koritnigite crystals from the Jáchymov ore district, Czech Republic, were recorded and interpreted. No substantial differences were observed between both crystal types. The observed Raman bands were attributed to the (AsO3OH)2− stretching and bending vibrations as well as stretching and bending vibrations of water molecules and hydroxyl ions. The non‐interpreted Raman spectra of koritnigite from the RRUFF database and the published infrared spectra of cobaltkoritnigite were used for comparison. The O H···O hydrogen bond lengths in the crystal structure of koritnigite were inferred from the Raman spectra and compared with those derived from the X‐ray single‐crystal refinement. The presence of (AsO3OH)2− units in the crystal structure of koritnigite was proved from the Raman spectra, which supports the conclusions of the X‐ray structure analysis. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

12.
    
The mixed anion mineral parnauite Cu9[(OH)10|SO4|(AsO4)2]·7H2O has been studied by Raman spectroscopy. Characteristic bands associated with arsenate, sulphate and hydroxyl units are identified. Broad bands are observed and are resolved into component bands. Two intense bands at 859 and 830 cm−1 are assigned to the ν1 (AsO4)3− symmetric stretching and ν3 (AsO4)3− antisymmetric stretching modes. The comparatively sharp band at 976 cm−1 is assigned to the ν1 (SO4)2− symmetric stretching mode and a broad‐spectral profile centered upon 1097 cm−1 is attributed to the ν3 (SO4)2− antisymmetric stretching mode. A comparison of the Raman spectra is made with other arsenate‐bearing minerals such as carminite, clinotyrolite, kankite, tilasite and pharmacosiderite. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

13.
    
The mineral dussertite, a hydroxy‐arsenate mineral with formula BaFe3+3(AsO4)2(OH)5, has been studied by Raman spectroscopy complemented with infrared spectroscopy. The spectra of three minerals from different origins were investigated and proved to be quite similar, although some minor differences were observed. In the Raman spectra of the Czech dussertite, four bands are observed in the 800–950 cm−1 region. The bands are assigned as follows: the band at 902 cm−1 is assigned to the (AsO4)3−ν3 antisymmetric stretching mode, the one at 870 cm−1 to the (AsO4)3−ν1 symmetric stretching mode, and those at 859 and 825 cm−1 to the As‐OM2 + /3+ stretching modes and/or hydroxyl bending modes. Raman bands at 372 and 409 cm−1 are attributed to the ν2 (AsO4)3− bending mode and the two bands at 429 and 474 cm−1 are assigned to the ν4 (AsO4)3− bending mode. An intense band at 3446 cm−1 in the infrared spectrum and a complex set of bands centred upon 3453 cm−1 in the Raman spectrum are attributed to the stretching vibrations of the hydrogen‐bonded (OH)− units and/or water units in the mineral structure. The broad infrared band at 3223 cm−1 is assigned to the vibrations of hydrogen‐bonded water molecules. Raman spectroscopy identified Raman bands attributable to (AsO4)3− and (AsO3OH)2− units. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

14.
    
The Raman spectrum of bukovskýite [Fe3+2(OH)(SO4)(AsO4)· 7H2O] has been studied and compared with that of an amorphous gel containing specifically Fe, As and S, which is understood to be an intermediate product in the formation of bukovskýite. The observed bands are assigned to the stretching and bending vibrations of (SO4)2− and (AsO4)3− units, stretching and bending vibrations and vibrational modes of hydrogen‐bonded water molecules, stretching and bending vibrations of hydrogen‐bonded (OH)− ions and Fe3+ (O,OH) units. The approximate range of O H···O hydrogen bond lengths was inferred from the Raman spectra. Raman spectra of crystalline bukovskýite and of the amorphous gel differ in that the bukovskýite spectrum is more complex, the observed bands are sharp and the degenerate bands of (SO4)2− and (AsO4)3− are split and more intense. Lower wavenumbers of δ H2O bending vibrations in the spectrum of the amorphous gel may indicate the presence of weaker hydrogen bonds compared to those in bukovskýite. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

15.
    
As one of the milestones in early-era nonlinear Raman studies, Akhmanov et al. [Sov. Phys. JETP 47 , 667 (1978)] and Koroteev et al. [Phys. Rev. Lett. 43 , 398 (1979)] have demonstrated that polarization coherent anti-Stokes Raman scattering (CARS) spectroscopy can resolve overlapping spectral lines that cannot be resolved by means of spontaneous Raman scattering spectroscopy and argued that the resolution of this method is unlimited. Here, we show that information theory offers useful insights into this remarkable result. We demonstrate that spectral super-resolution attainable in polarization CARS can be understood in terms of the Fisher information and the pertinent Cramér–Rao lower bound. We show that, with a suitable polarization arrangement, coherent Raman scattering can be tailored to yield super-resolving spectral modes that provide a nonvanishing Fisher information even for deeply sub-Rayleigh spectral features, preventing the variance of spectral measurements from diverging no matter how fine these spectral features are. When the nonresonant coherent background scattering can be efficiently suppressed, the Fisher information of such super-resolving modes reaches its upper bound as dictated by its quantum version—the quantum Fisher information.  相似文献   

16.
    
Polarized Raman spectroscopy was used to investigate the room‐temperature phonon characteristics of a series of rare‐earth arsenate (REAsO4, RE = Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu) single crystals. The Raman data were interpreted in a systematic manner based on the known tetragonal zircon structure of these compounds, and assignments and correlations were made for the observed bands. We found that the wavenumbers of the internal modes of the AsO4 tetrahedron increased with increasing atomic number. This increase seems to be correlated to the contraction of the RE–O bond length. For three out of four lattice wavenumbers observed, this tendency was not nearly so marked as in the case of the internal mode wavenumber. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

17.
    
Raman spectroscopy has been used to study the rare‐earth mineral churchite‐(Y) of formula (Y,REE)(PO4) ·2H2O, where rare‐earth element (REE) is a rare‐earth element. The mineral contains yttrium and, depending on the locality, a range of rare‐earth metals. The Raman spectra of two churchite‐(Y) mineral samples from Jáchymov and Medvědín in the Czech Republic were compared with the Raman spectra of churchite‐(Y) downloaded from the RRUFF data base. The Raman spectra of churchite‐(Y) are characterized by an intense sharp band at 975 cm−1 assigned to the ν1 (PO43−) symmetric stretching mode. A lower intensity band observed at around 1065 cm−1 is attributed to the ν3 (PO43−) antisymmetric stretching mode. The (PO43−) bending modes are observed at 497 cm−1 (ν2) and 563 cm−1 (ν4). Some small differences in the band positions between the four churchite‐(Y) samples from four different localities were found. These differences may be ascribed to the different compositions of the churchite‐(Y) minerals. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

18.
梁瑞生  张坤明 《光学学报》1993,13(5):99-404
介绍喇曼感生克尔效应光谱(RIKES)的琼斯(Jones)矩阵分析方法.探测光束的传输强度不仅由所经过的每一个光学器件的琼斯矩阵所决定,而且还受到强的泵波在非线性介质样品中感生依赖于强度的二向色性和双折射(克尔效应)对琼斯矩阵的影响.同时计及样品和光学器件由强泵波作用下感生应力和其他外部产生的线双折射对喇曼感生克尔效应光谱观察的不利影响,导出测量系统的功率传输函数的完整表达式和喇曼感生克尔效应光谱的实现观察条件,最后简述以甲笨(C_7H_8)液体为试样的喇曼感生克尔效应光谱实验结果分析.  相似文献   

19.
    
Raman spectroscopic techniques are a group of chemical fingerprint detection methods based on molecular vibrational spectroscopy. They are compatible with aqueous solutions and are time saving, nondestructive, and highly informative. With complementary and alternative medicine (CAM) becoming increasingly popular, more people are consuming natural herbal medicines. Thus, chemical fingerprints of herbal medicines are investigated to determine the content of these products. In this study, I review the different types of Raman spectroscopic techniques used in fingerprinting herbal medicines, including dispersive Raman spectroscopy, resonance Raman spectroscopy, Fourier transform (FT)–Raman spectroscopy, surface-enhanced Raman scattering (SERS) spectroscopy, and confocal/microscopic Raman spectroscopy. Lab-grade Raman spectroscopy instruments help detect the chemical components of herbal medicines effectively and accurately without the need for complicated separation and extraction procedures. In addition, portable Raman spectroscopy instruments could be used to monitor the health and safety compliance of herbal products in the consumer market.  相似文献   

20.
    
Time‐resolved Raman spectroscopy, spatially offset Raman spectroscopy and time‐resolved spatially offset Raman spectroscopy (TR‐SORS) have proven their capability for the non‐invasive profiling of deep layers of a sample. Recent studies have indicated that TR‐SORS exhibits an enhanced selectivity toward the deep layers of a sample. However, the enhanced depth profiling efficiency of TR‐SORS, in comparison with time‐resolved Raman spectroscopy and spatially offset Raman spectroscopy, is yet to be assessed and explained in accordance to the synergistic effects of spatial and temporal resolutions. This study provides a critical investigation of the depth profiling efficiency of the three deep Raman techniques. The study compares the efficiency of the various deep Raman spectroscopy techniques for the stand‐off detection of explosive precursors hidden in highly fluorescing packaging. The study explains for the first time the synergistic effects of spatial and temporal resolutions in the deep Raman techniques and their impact on the acquired spectral data. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号