以合成包裹体为腔体进行高温下流体的拉曼光谱原位分析

在冷封口的水热高压容器中 ,合成了组成分别为H2 O 4 2 0wt%CO2 和H2 O 8 4 2wt%CO2 的两种流体包裹体。以此合成的包裹体作为腔体 ,用显微激光拉曼探针测量了其中液态流体在 2 90 0～ 380 0cm-1范围的高温拉曼光谱 ,对其中液态水的氢键随温度的变化进行了讨论。研究结果表明 ,随着温度升高 ,流体中水分子的氢键作用不断减弱。组成为H2 O 4 2 0wt%CO2 的包裹体 ,在 372℃均一为液体 ,均一时 ,水分子的氢键发生了突变 ,均一后 ,氢键受温度的影响比较小 ,到 5 5 0℃它还存在着比较强的氢键作用。组成为H2 O 8 4 2wt%CO2 的流体在 6 0 6℃时由气液两相变为纯气相 ,一直到拉曼光谱测量的最高温度 5 80℃ ,液态水还保持着比较强的氢键作用。     

一种含SiO2氧化物玻璃的晶化温度-压力依赖关系

 本文应用DTA及X射线衍射法在常压及高压下对一种含SiO₂的锂离子导体玻璃0.3Li₂O-0.67SiO₂-0.03V₂O₅加热时的晶化行为进行了研究。该氧化物玻璃的晶化过程分两个阶段。在常压下，第一晶化过程发生在560 ℃附近，析出相为Li₂O·2SiO₂。对应的晶化温度T_x1随压力的升高发生了急剧的变化。从常压到0.3 GPa，T_x1从560 ℃升高到620 ℃；继续升压时T_x1突然下降，并在0.4 GPa处跌到528 ℃，呈现一个陡峭的峰值。0.4 GPa以上，T_x1随压力的变化则呈常规行为，比较平稳地，大致线性地升高，一直到最高测定压力2 GPa。 本文最后对这些行为的可能原因进行了讨论。     

Bi1.8Nd0.2Ti4O11的温致及压致软模相变研究

 采用背用散射的方法，测量了Bi_1.8Nd_0.2Ti₄O₁₁的拉曼光谱。实验结果表明，该掺杂样品发生温致和压致软模相变的温度和压力分别为200 ℃和3.35 GPa。文中讨论了相变点移动的原因及高频声子模随温度和压力的变化。     

CH4-O2-N2预混气体爆炸二维数值模拟

 利用CFD软件,基于ISAT算法和简化的甲烷氧化基元反应模型,建立了CH₄-O₂-N₂预混气体的二维湍流爆炸模型。数值计算结果表明,该模型较好地模拟了CH₄-O₂-N₂预混气体在高温气团作用下的点火、燃烧和爆炸过程。计算中,考察了高温点火气团的初始温度和混合气体初始组分对CH₄-O₂-N₂预混气体燃烧和爆炸过程的影响。结果表明：高温气团的初始温度对CH₄-O₂-N₂预混气体的点火延迟时间和燃烧初始阶段有重要影响,但对CJ爆燃没有影响;惰性气体N₂的加入,降低了混合气体的反应活性,导致点火延迟时间增大,燃烧反应速度、爆炸超压和重要自由基浓度都随之减小。相同条件下爆炸超压峰值的计算结果与实验测量结果符合较好。     

高温高压下SrB4O7：Eu2+玻璃的晶化

 利用X射线衍射和Eu²⁺发射光谱方法研究了非晶玻璃SrB₄O₇在高温高压下的晶化。结果表明：在5.0 GPa压力下，200 ℃仍为玻璃态，只有几个强度极低的小峰，表明有晶化的迹象；600 ℃时已基本晶化，但为SrB₄O₇正交相与SrB₄O₇高压立方相二相共存；当温度提高到1 000 ℃时，晶化成了近单相的与常压SrB₄O₇粉末晶体相同的正交结构。伴随晶化度的加强，Eu²⁺发射强度增强，与Ｘ射线衍射结果相一致。     

PbMoO4原位高压拉曼光谱和电导率的研究

 钼酸铅（PbMoO₄）具有高的声光品质因数、低的声损耗、良好的声阻抗匹配等性质，被广泛应用于声光偏转器、调制器、可调滤光器、声表面波器件等各类声光器件，其优异的低温闪烁性能亦引起人们的注意，具有在核设备方面的应用潜力。为探讨其晶体结构和物理性质，在金刚石对顶砧上原位测量了PbMoO₄的拉曼光谱，并测量了其在几个不同压力点下电导率随温度的变化。实验发现，压力在12.5 GPa时，拉曼峰完全消失，说明压力在10.8～12.5 GPa之间PbMoO₄样品出现了非晶态转变。当从26.5 GPa卸压到9.4 GPa时，PbMoO₄的拉曼谱在低波数出现无序化，而在2.4 GPa压力下858 cm^-1峰又重新出现，说明样品结构由无序向晶化回复。压力在10.8 GPa以上时，电导率随着温度的增加而显著增加，且随着压力的增加也明显增加。     

常温高压下水的拉曼谱峰标定压力的研究

 利用金刚石压腔测定了26 ℃高压下水的O—H伸缩振动拉曼谱峰的变化,并对其进行分峰处理,初步确定了水的拉曼拟合峰ν_{3 244}的峰位置与体系压力的关系,且论证了利用水的拉曼拟合峰ν_{3 244}的变化标定金刚石压腔压力的优点以及应用上的局限性。实验结果表明：26 ℃时,在实验的压力范围内,由水的拉曼谱峰拟合得到的ν_{3 244}峰位置随着体系压力的增加呈线性减小。其关系式为p (MPa)=32.9(ν_p)_{3 244}+200.7（3 215 cm^-1< ν_{3 244}<3 244 cm^-1）。     

冷压与热压处理对YBa2Cu3O7-δ的结构相变和超导电性的影响

 本文研究了冷压（2.2~5.2 GPa）与热压（2.2 GPa,2.50~950 ℃）对YBa₂Cu₃O_7-δ的正交→四方相转变区和超导电性的影响。冷压保持其正交结构,但破坏了超导性,在98 K（失超点）到室温呈半导体特性,再在空气中烧结,可恢复液氮温区的零电阻状态。以Cu锅密封样品,热压处理至950 ℃,不发生Cu的析出。热压处理后,98 K（失超点）到室温呈半导体特性,再经通氧烧结,于86 K出现零电阻。热压处理过程,从450~950 ℃为正交→四方转变区。950 ℃为转变结束温度,大大高于氧气、空气、氮气、真空状态的温度。400 ℃附近为起始转变温度,低于氮气、氧气气氛的温度。因此相变区加宽。T_0-t结束温度升高,与Cu锅的抑制还原作用有密切关系。如降低高压淬火速率（<<10² ℃/s）,或随后辅以氧气氛中的后处理,将有利于获得既有高密度又有高T_c的YBa₂Cu₃O_7-δ超导体。     

高温高压合成电子型掺杂层状钙钛矿结构锰氧化物La2-2xCa1+2xMn2O7

 用高温高压法、在1 260 ℃和5.0 GPa条件下,成功制备出电子型掺杂层状钙钛矿结构锰氧化物La_2-2xCa_1+2xMn₂O₇（x=1.0～0.8）系列样品。样品的粉末X射线衍射实验和Rietveld精修结构分析表明,所制样品具有Sr₃Ti₂O₇型四方结构,空间群为I4/mmm。随着电子浓度的增加,MnO₆八面体畸变程度增大,晶胞体积增加。同时样品的磁化强度随La的掺入、x的增加而增强,反铁磁有序温度T_N提高。由于双交换作用减小,样品的电阻增加。在测量温度范围内,没有观测到磁电阻效应。     

爆轰和燃烧法合成SrAl2O4：Eu2+，Dy3+纳米发光粉

 在低温条件下分别用爆轰法和燃烧法制备出了SrAl₂O₄：Eu²⁺,Dy³⁺ 纳米发光粉。从合成条件、热处理温度等方面详细对比了爆轰法和燃烧法对所制备的SrAl₂O₄：Eu²⁺,Dy³⁺纳米发光粉的晶体生长行为、粒子形貌和光学性质等的影响。研究表明,随着热处理温度的升高,爆轰法制备的纳米发光粉的平均粒径逐渐增大,而燃烧法制备的纳米发光粉的平均粒径先减小后增大,在600 ℃时平均粒径存在一个极小值。在同样热处理温度下,爆轰法制备的纳米发光粉的平均粒径增长明显高于燃烧法合成的纳米发光粉的平均粒径。最后讨论了长余辉的发光机理,并给出了如何改进合成方法的建议。     

纳米SiO2形成柯石英的p-T相图

 使用纳米SiO₂粉体为原料,在2.0～4.2 GPa、150～1200 ℃范围内进行了一系列的高压高温实验研究,得到了该压力温度范围内晶化产物α-石英与柯石英的p-T相图,而且该相图中的相边界在650 ℃以下斜率为负,在650 ℃以上基本水平。通过X射线衍射仪（XRD）、Raman光谱仪（Raman）、傅立叶红外光谱仪（FT-IR）、DSC-TGA差热分析仪（TG-DTA）-等表征手段,发现纳米SiO₂原粉中水分（包含Si－OH和吸附水）的存在能显著降低合成柯石英的温度和时间,在4.2 GPa压力下得到了目前合成柯石英的最低温度190 ℃。常压下,合成的柯石英在800 ℃以下能够稳定存在,在1 000 ℃以上转化为α-方石英。     

斜锆石（ZrO2）高温高压相变的Raman光谱研究

 以Ar作压力介质，在0~23 GPa压力范围内，利用金刚石压腔装置（DAC）和激光加温技术，采用显微拉曼光谱进行原位测试，对处于准静水压力条件下的斜锆石开展高温高压相变研究。研究结果表明：室温下斜锆石ZrO₂于3.4 GPa时开始发生相变，到10.4 GPa时其明显转变成一个空间群为Pbca的斜方相。此新相随着压力升高，直到15.3 GPa，仍稳定存在。通过研究，首次获得了Pbca相的拉曼谱图。随后在15.3 GPa压力下进行了激光加温后淬火，结果发现，加热前的Pbca相又转变成了空间群为Pnam的PbCl₂结构类型的高压相，该相直到实验最高压力23 GPa仍稳定存在。     

Rotational CARS N2 thermometry: validation experiments for the influence of nitrogen spectral line broadening by hydrogen

Rotational coherent anti‐Stokes Raman spectroscopy (CARS) in fuel‐rich hydrocarbon flames, with a large content of hydrogen in the product gases (∼20%), has in previous work shown that evaluated temperatures are raised several tens of Kelvin by taking newly derived N₂ H₂ Raman line widths into account. To validate these results, in this work calibrated temperature measurements at around 300, 500 and 700 K were performed in a cell with binary gas mixtures of nitrogen and hydrogen. The temperature evaluation was made with respect to Raman line widths either from self‐broadened nitrogen only, N₂ N₂ [energy‐corrected‐sudden (ECS)], or by also taking nitrogen broadened by hydrogen, N₂ H₂ [Robert–Bonamy (RB)], Raman line widths into account. With increased amount of hydrogen in the cell at constant temperature, the evaluated CARS temperatures were clearly lowered with the use of Raman line widths from self‐broadened nitrogen only, and the case with inclusion of N₂ H₂ Raman line widths was more successful. The difference in evaluated temperatures between the two different sets increases approximately linearly, reaching 20 K (at T ∼ 300 K), 43 K (at T = 500 K) and 61 K (at T = 700 K) at the highest hydrogen concentration (90%). The results from this work further emphasize the importance of using adequate Raman line widths for accurate rotational CARS thermometry. Copyright © 2010 John Wiley & Sons, Ltd.     

变温过程中二甲基亚砜与水之间氢键行为的拉曼光谱研究

测量了在降温过程中体积比为1∶1的二甲基亚砜(DMSO)水溶液的拉曼光谱,并对DMSO水溶液的拉曼光谱进行了归属。对实验数据进行分析发现: 在降温过程中DMSO分子与水分子的分子间氢键、DMSO分子与DMSO分子和水分子与水分子间氢键的作用行为引起了DMSO的SO双键和水分子的O—H键的拉曼谱带的变化。进一步分析表明：在27～-30 ℃降温过程DMSO与水之间氢键加强,-30～-60 ℃降温过程水与水之间氢键代替DMSO与水之间的氢键。这为丰富水溶液的氢键理论提供了实验依据。     

Dual-broadband CARS temperature measurements in hydrogen-oxygen atmospheric pressure flames

Dual-broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy of the Q₀₁-branch of H₂ has been employed for thermometry in an atmospheric-pressure hydrogen-oxygen flame. The aim was to investigate the applicability of the technique for single-shot temperature evaluation and to analyse the precision of the measurements. The results are presented of temperature and relative H₂ density mapping of the flame in the temperature range of 700-2800 K. The achieved precision of single-shot measurements was 3-5%.     

Raman microscopy of haidingerite Ca(AsO3OH)·H2O and brassite Mg(AsO3OH)·4H2O

Raman spectroscopy has been used to study the arsenate minerals haidingerite Ca(AsO₃OH)·H₂O and brassite Mg(AsO₃OH)·4H₂O. Intense Raman bands in the haidingerite spectrum observed at 745 and 855 cm⁻¹ are assigned to the (AsO₃OH)²⁻ν₃ antisymmetric stretching and ν₁ symmetric stretching vibrational modes. For brassite, two similarly assigned intense bands are found at 809 and 862 cm⁻¹. The observation of multiple Raman bands in the (AsO₃OH)²⁻ stretching and bending regions suggests that the arsenate tetrahedrons in the crystal structures of both minerals studied are strongly distorted. Broad Raman bands observed at 2842 cm⁻¹ for haidingerite and 3035 cm⁻¹ for brassite indicate strong hydrogen bonding of water molecules in the structure of these minerals. OH···O hydrogen‐bond lengths were calculated from the Raman spectra based on empirical relations. Copyright © 2009 John Wiley & Sons, Ltd.     

灯丝温度对原位吸收光谱和金刚石薄膜生长的影响

 报道了原位红外吸收光谱在气相合成金刚石薄膜生长过程中的应用，研究了灯丝温度对原位红外吸收光谱和金刚石薄膜生长的影响。较高的灯丝温度使甲烷分解更充分，从而产生更多诸如C₂H₂等可能对金刚石薄膜生长有利的基团，导致金刚石薄膜质量和生长速率的提高。     

Raman Investigation of Sodium Titanate Nanotubes under Hydrostatic Pressures up to 26.9GPa

High pressure behavior of sodium titanate nanotubes （Na2Ti2O5） is investigated by Raman spectroscopy in a diamond anvil cell （DAC） at room temperature. The two pressure-induced irreversible phase transitions are observed under the given pressure. One occurs at about 4.2 GPa accompanied with a new Raman peak emerging at 834 cm-1 which results from the lattice distortion of the Ti-O network in titanate nanotubes. It can be can be assigned to Ti-O lattice vibrations within lepidocrocite-type （H0.7Ti1.825V0.175O4＆#12539;H2O）TiO6 octahedral host layers with V being vacancy. The structure of the nanotubes transforms to orthorhombic lepidocrocite structure. Another amorphous phase transition occurs at 16.7 GPa. This phase transition is induced by the collapse of titanate nanotubes. All the Raman bands shift toward higher wavenumbers with a pressure dependence ranging from 1.58-5.6 cm-1/GPa.     

The structural independence of Raman scattering cross sections of ν1(NO3−) and ν(H2O)

The Raman scattering cross section (RSCS) is an important parameter in the applications of Raman spectroscopy to make quantitative analysis. To date, the dependence of the RSCS on concentration has remained unclear. Nitrate aerosols can easily achieve a supersaturated state, which provides a way to obtain the RSCS especially under this state. In this study, Raman spectra of NaNO₃ and Mg(NO₃)₂ solutions are obtained with molar water‐to‐solute ratios (WSRs) ranging from 84.2 to 2.30 and 93.8 to 7.32, respectively. With decreasing WSR, a shift to higher wavenumbers of the symmetric stretching band of nitrate ion, i.e. ν₁(NO₃⁻), is observed, indicating the formation of various ion pairs. Meanwhile, the area ratio between the strongly and weakly hydrogen‐bonded components of water O H stretching envelope, i.e. ν(H₂O), reduces as the WSR decreases, implying the transformation of water molecules from strong hydrogen‐bonding structures to the weak ones. However, a good linear relationship is revealed between the integrated intensity ratio of the ν(H₂O) band to ν₁(NO₃⁻) band and WSR. The results suggest that the RSCSs of NO₃⁻ and H₂O are insensitive to the structures of both ion pairs and hydrogen‐bonding structures. This observation points to the possibility of conducting quantitative analysis through the area ratio of the ν(H₂O) band to the ν₁(NO₃⁻) band with Raman spectra without considering the formation of ion pairs and the variation of the hydrogen‐bonding structure. Copyright © 2011 John Wiley & Sons, Ltd.     

Large Relative Raman Shift for Molecules Adsorbed on Metallic Nano-particles

The enhancement of two order-of-magnitudes is observed in surface-enhanced Raman spectroscopy （SERS） of gases （CO, C2H2, C2H4, etc） adsorbed on nitric acid-roughened metal foil. In addition, some Raman lines of gases adsorbed on these active substrates show larger frequency shifts and linewidth broadening, compared with the Raman spectroscopy of free gases. Using the two-oscillator electromagnetic model, we explain this phenomenon. It is related to the large non-regular particles on the active substrate we prepared. It is found that the parameters of the surface-plasmon dispersion, the distance of molecules from the surface and the radius of particles play crucial roles on the relative large Raman shifts.