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1.
燃油的无硫化成为车用燃料发展的必然趋势.为开发高性能的柴油超深度加氢脱硫催化剂,文章采用CO吸附原位红外光谱法对系列还原态Co-Mo/Al2O3催化剂和高活性工业剂进行了表征,并将表征结果与微反加氢脱硫活性评价结果进行了关联分析.结果表明:随金属负载量的变化CO吸附的光谱特征发生变化,当MoO3负载量达20%、助剂CoO量为4.16%时,在2 179 cm-1出现一个新的CO特征吸收峰,该活性中心的出现明显有利于加氢脱硫(HYD)的反应.在相同金属负载量的情况下,与采用化学处理法制备的催化剂相比较,后者对应的2179 cm-1的特征吸收明显增强,微反评价显示该催化剂的催化活性特别是HYD反应活性明显提高.  相似文献   

2.
为减少汽车尾气排放,应对越来越严格的燃油质量标准,对催化裂化汽油进行选择性加氢脱硫(HDS)是生产低硫汽油的重要技术.提高HDS活性、减少烯烃的饱和是选择性加氧脱硫催化剂研制的关键,而催化剂中活性相状态及其分布将决定催化剂的性能.认识催化剂的活性相状态及其与催化剂性能的关系,有助于研制、开发高性能的HDS催化剂.采用C...  相似文献   

3.
绿松石的激光拉曼光谱研究   总被引:1,自引:0,他引:1  
对湖北、安徽地区绿松石进行了激光拉曼光谱测试分析.结果表明,绿松石中 H2O,OH-及PO34-的基团振动是导致其激光拉曼光谱形成的主要原因.3 510~3 440 cm-1的谱峰是由v(OH)伸缩振动所致,其中v(OH)振动导致的强拉曼特征谱峰在3 470 cm-1附近,v(H2O)伸缩振动致拉曼谱峰位于3 290~3 070cm-1附近的较为宽缓的弱谱峰处;由v3(PO4)伸缩振动致强拉曼特征谱峰在1 200~1 030 cm-1之间,其中v3(PO4)振动导致的强拉曼特征谱峰在1 039 cm-1附近,地(PO4)弯曲振动位于650~540 cm-1叫范围,v2(PO4)的弯曲振动谱峰位于500~410 cm-1处;不同产地、不同结晶类型的绿松石表现出的拉曼谱峰特征鼢基本一致.  相似文献   

4.
激光光源条件对谷氨酸钠拉曼光谱的影响   总被引:6,自引:1,他引:5  
采用多种激光和不同功率等,对谷氨酸钠晶体进行了激光拉曼光谱的影响研究.结果表明不同波长和功率的光源,对测定存在一定的影响,谱峰位移在6 cm-1以内.紫外激光由于光能量较大对样品有一定的破坏作用,造成拉曼光谱的减弱和泯灭,需采用光路衰减.拉曼谱峰的响应与光源的功率有着很好的线性关系,其相关系数r≥0.999.首次提出单位光功率所产生的拉曼光强与所用的波长有关,与所用的光功率无关.  相似文献   

5.
应用同步辐射Eextended X-ray Ab sorption Fine S tructure(EXAFS)技术研究固态法制备的KHMoY分子筛的氧化态和硫化态样品以及硫化态KHY/MoO3样品中钼组分的局域配位环境结构,并与KHMoY和KHY/MoO3 样品催化加氢活性结果进行对照。结果表明,随原子比(K+2Mo)/Al的变化,钼原子周围的配位环境有显著的差异。当(K+2Mo)/Al时,KHMoY和KHY/MoO3硫化后,钼组分主要以MoS2小原子簇分散在分子筛超笼中;(K+2Mo)/Al>1时,钼组分则有两种存在环境,即分子筛超笼中的和分子筛外表的钼组分。分子筛超笼中的Mo S2原子簇的催化加氢合成醇选择性较高;分子筛外表面的MoS2微小颗粒的尺寸相对于超笼中的要大许多,其合成醇选择 性较低。  相似文献   

6.
应用光镊子拉曼光谱鉴别阴道毛滴虫和口腔毛滴虫的研究   总被引:2,自引:0,他引:2  
应用激光镊子拉曼光谱技术比较分析阴道毛滴虫和口腔毛滴虫的拉曼吸收峰,寻找具有分类学鉴别价值的特征拉曼峰。通过光镊随机俘获单个大小一致、有活力的虫体,记录其拉曼光谱,收集数据并做主成分分析。在937cm-1、1002cm-1和1446cm-1谱峰的强度和谱型上有差异,根据1002cm-1峰的信号强度,并结合937cm-1和1002cm-1峰强度比值(I937/I1002)以及1002cm-1和1446cm-1峰强度比值(I1002/I1446)可以作为区分阴道毛滴虫和口腔毛滴虫的量化指标。该法是简便、快捷、有效地鉴别两种人体毛滴虫的新方法。  相似文献   

7.
CVD金刚石膜中1145cm~(-1)拉曼峰的研究   总被引:5,自引:1,他引:4  
用拉曼光谱手段对CVD方法生长的金刚石膜,特别是其中最有争议的1145cm-1附近的拉曼峰进行了研究。用不同波长激光激发得到此峰的拉曼谱与量子尺寸选择效应所预期规律的相反,反驳了将1145cm-1附近的拉曼峰指认为纳米晶金刚石本征峰的说法。而通过对不同样品的比较,从侧面支持了将它归结为杂质,即反式聚乙炔的指认。更进一步通过分析不同尺寸的样品中杂质峰的相对强度,提出了这个峰的强度或许可以作为金刚石晶粒尺寸判据的建议。  相似文献   

8.
常温、1.0~4.4GPa下,利用激光拉曼光谱研究了奥长石晶体结构随压力的变化。发现,压力为2.9GPa时,517cm-1附近出现新的谱峰,奥长石开始相变。3.4GPa时,源于奥长石结构中M—O伸缩振动的288cm-1拉曼谱峰频移发生突变,517cm-1附近谱峰消失,奥长石由三斜晶系完全相变为单斜晶系(P1-I1)。随压力增加,归属于奥长石四面体结构中Si—O—Si弯曲振动的458及516cm-1谱峰随压力增加有规律地向高频方向偏移,斜率分别是1.667cm-1/GPa和3.560cm-1/GPa,而源于Al—O—Al弯曲振动的480cm-1谱峰与压力没有明显的线性变化关系。卸压过程中,288cm-1拉曼谱峰频移保持不变,458,480及516cm-1谱峰向低频偏移。长石类矿物的相变压力与结构中八元环所含阳离子种类有关。  相似文献   

9.
对汶川地震断裂带深溪沟出露的基岩错动面两侧岩脉中的石英矿物进行了拉曼谱峰测定,并根据所测石英的464cm-1拉曼谱峰向高波数的偏移量估算了断裂带中的压应力分布。测试结果表明,错动面附近岩脉中石英的464cm-1拉曼谱峰向高波数偏移量为3.29cm-1,相应的压应力值为368.63 MPa,明显低于错动面两侧应力积累,这可能是由于错动面的多次活动导致了应力不断得到释放。断裂南东盘(下盘)远离错动面,岩脉中石英的464cm-1拉曼谱峰向高波数偏移量具有增加的趋势,相应的应力积累也逐渐增强,距错动面21m处的石英样品的464cm-1拉曼谱峰向高波数偏移4.40cm-1,相应压应力可达到494.77MPa。剖面北西盘(上盘)在距错动面10m处,样品464cm-1拉曼谱峰的偏移量达到最大值,相应的应力积累为519.87 MPa,其后远离错动面应力积累开始减弱,在北西盘17 m处,应力积累骤然下降至400.37MPa。在西北盘距错动面27m处,岩脉石英的464cm-1拉曼谱峰向高波数偏移量下降至3.21cm-1,应力已经减弱到359.59 MPa,这可能是由于该处位于断裂带的边缘,远离错动面,受到了较小的断层活动的影响。因此,汶川地震断裂带内的应力虽然得到部分释放,但剩余的应力分布并不均匀,而且在局部还存在较高的应力积累,这反应了断裂带中岩石的力学性质在空间上具有不均匀性。  相似文献   

10.
对汶川地震断裂带深溪沟出露的基岩错动面两侧岩脉中的石英矿物进行了拉曼谱峰测定, 并根据所测石英的464 cm-1拉曼谱峰向高波数的偏移量估算了断裂带中的压应力分布。测试结果表明, 错动面附近岩脉中石英的464 cm-1拉曼谱峰向高波数偏移量为3.29 cm-1, 相应的压应力值为368.63 MPa, 明显低于错动面两侧应力积累, 这可能是由于错动面的多次活动导致了应力不断得到释放。断裂南东盘(下盘)远离错动面, 岩脉中石英的464 cm-1拉曼谱峰向高波数偏移量具有增加的趋势, 相应的应力积累也逐渐增强, 距错动面21 m处的石英样品的464 cm-1拉曼谱峰向高波数偏移4.40 cm-1, 相应压应力可达到494.77 MPa。剖面北西盘(上盘)在距错动面10 m处, 样品464 cm-1拉曼谱峰的偏移量达到最大值, 相应的应力积累为519.87 MPa, 其后远离错动面应力积累开始减弱, 在北西盘17 m处, 应力积累骤然下降至400.37 MPa。在西北盘距错动面27 m处, 岩脉石英的464 cm-1拉曼谱峰向高波数偏移量下降至3.21 cm-1, 应力已经减弱到359.59 MPa, 这可能是由于该处位于断裂带的边缘, 远离错动面, 受到了较小的断层活动的影响。因此, 汶川地震断裂带内的应力虽然得到部分释放, 但剩余的应力分布并不均匀, 而且在局部还存在较高的应力积累, 这反应了断裂带中岩石的力学性质在空间上具有不均匀性。  相似文献   

11.
The silicates Ca3Sc2Si3O12, Ca3Y2Si3O12 and Ca3Lu2Si3O12, both undoped and doped with Pr3+ ions, have been synthesized by solid-state reaction at high temperature. The luminescence spectroscopy and the excited state dynamics of the materials have been studied upon VUV and X-ray excitation using synchrotron radiation. All doped samples have shown efficient 5d-4f emission upon direct VUV excitation of 5d levels, but only Ca3Sc2Si3O12:Pr3+ shows luminescence upon interband VUV or X-ray excitation. The VUV excited emission spectra of Ca3Y2Si3O12:Pr3+ and Ca3Lu2Si3O12:Pr3+ show features attributed to emission from two distinct sites accommodating the Pr3+ dopant. The decay kinetics of the Pr3+ 5d-4f emission in Ca3Sc2Si3O12:Pr3+ upon VUV excitation across the band gap are characterized by decay times in the range 25-28 ns with no significant rise after the excitation pulse. They appear to be faster upon X-ray irradiation than for VUV excitation. Weak afterglow components are attributed to defect luminescence.  相似文献   

12.
Bi1.5Zn1.0Nb1.5O7/Ba0.6Sr0.4TiO3/Bi1.5Zn1.0Nb1.5O7 tunable multilayer thin film has been fabricated by pulsed laser ablation and characterized. Phase composition and microstructure of multilayer films were characterized by X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The film has very smooth surface with RMS roughness of 1.5-2 nm and grain size of 100-150 nm. Total film thickness has been measure to be 375 nm. The BZN thin films at 300 K, on Pt(1 1 1)/SiO2/Si substrate showed zero-field dielectric constant of 105 and dielectric loss tangent of 0.002 at frequency of 0.1 MHz. Thin films annealed at 700 °C shows the dielectric tunability of 18% with biasing field 500 kV/cm at 0.1 MHz. The multilayer thin film shows nonferroelectric behavior at room temperature. The good physical and electrical properties of multilayer thin films make them promising candidate for tunable microwave device applications.  相似文献   

13.
在1064 nm波长脉冲激光(脉宽25 ps)的照射下,钙钛矿氧化物薄膜La0.67Ca0.33MnO3/SrTiO3具有超快光电效应,对激光脉冲显示ps量级的响应时间,上升沿响应时间300 ps,半高宽700 ps,同时,对激光能量的响应灵敏度为500 mV/mJ。  相似文献   

14.
In this paper we report the study of the perovskites La0.7Ca0.3Mn0.5Co0.5O3 and La0.8Sr0.2Mn0.5Co0.5O3 by neutron powder diffraction at various temperatures and magnetization measurements in zero applied field and at low cooling regimes. The replacement of half Mn by Co in La0.7Ca0.3MnO3 and La0.8Sr0.2MnO3 destroys their long-range ferromagnetism exhibiting a cluster glass ferromagnetic order similar to the one observed in many cobaltites.  相似文献   

15.
闫树科  包瑾  苏喜平  徐晓光  姜勇 《物理学报》2008,57(4):2504-2508
采用直流磁控溅射方法制备了一系列的合成反铁磁及以其为自由层的自旋阀.研究发现,在Ni81Fe19与Ru层之间插入适当厚度的Co90Fe10层后,可有效地提高合成反铁磁两磁性层间的反铁磁耦合强度,得到具有饱和场Hs更高、饱和磁化强度Ms更低、热稳定性更好的合成反铁磁.另外,以这种合成反铁磁作自旋阀的自由层时,可有效提高自旋阀的稳定性. 关键词: 合成反铁磁 退火 自旋阀  相似文献   

16.
17.
The influence of the prehistory on the electrical properties of layered ferroelectrics is investigated. It is established that the heating of short-circuited samples of the nonpolarized ceramic material Na0.5Bi8.5Ti2Nb4O27 leads to the appearance of maxima of the current at temperatures below the Curie point only in the case of preliminary ageing of the samples. Original Russian Text ? A.I. Burkhanov, Yu.V. Kochergin, K. Bormanis, A. Kalvane, M. Dambekalne, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51, No. 7, pp. 1393–1394.  相似文献   

18.
Boundaries of morphotropic phase transitions region in the system of solid solutions K2Pb4Nb10O30-Na2Pb4Nb10O30-K6W4Nb6O30 with the structure of the tetragonal tungsten bronze have been specified. Presence of the second morphotropic phase transition, perpendicular to the first one has been revealed. The temperature dependences of the structural parameters of some compounds have been investigated. The compounds with high values of Curie temperatures and working temperatures have been obtained.  相似文献   

19.
This work reports on the phase formation during a solid-state reaction of Eu3+-doped garnets with the general formula A3B2Ge3O12 (A=Ca, Sr and B=Ga, In, Y) and their luminescent properties. It is shown by XRD and DTA/TG experiments that the garnet-phase formation is completed at 1100-1200 °C. Moreover, it turned out that the position of the oxygen to europium charge-transfer band and the intensity of the forbidden 4f-4f transitions of Eu3+ is dependent on the covalent interaction between the Eu3+ activator and the surrounding oxygen anions. The investigated red-emitting luminescent materials show high lumen equivalents and deep red emission at the same time, which makes them attractive for the application in LEDs (light emitting diodes), in particular for near UV-emitting LEDs.  相似文献   

20.
K. Senapati  R. C. Budhani 《Pramana》2007,69(2):267-275
An experimental study of proximity effect in La0.67Sr0.33MnO3-YBa2CU3O7-La0.67Sr0.33MnO3 trilayers is reported. Transport measurements on these samples show clear oscillations in critical current (I c) as the thickness of La0.67Sr0.33MnO3 layers (d F) is scanned from ∼50 ? to ∼ 1100 ?. In the light of existing theories of ferromagnet-superconductor (FM-SC) heterostructures, this observation suggests a long range proximity effect in the manganite, modulated by its weak exchange energy (∼2 meV). The observed modulation of the magnetic coupling between the ferromagnetic LSMO layers as a function of d F, also suggests an oscillatory behavior of the SC order parameter near the FM-SC interface.   相似文献   

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