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本文采用全相对论量子力学计算了H2X (X=O, S, Se, Te) 分子的双光子过程, 并考虑相对论效应对双光子过程的影响. 结果表明, 各个不可约表示对称态下激发能有着明显的差异,它反应了双光子吸收过程中选择能级的特点. 同时, 采用非相对论的对称匹配簇/组态相互作用方法 (SAC-CI) 计算其分子的单光子激发, 并与之比较. 双光子跃迁概率要比单光子跃迁概率小2–5个数量级; 同一主族, 随着原子序数的增加, 相对论效应对分子体系的激发能量、跃迁概率、振子强度的大小都有显著地影响; 除此之外,每个分子遵守分子对称群的选择原则. 本文中, 分子H2X (X=O, S, Se, Te) 的个别不可约表示对称态的跃迁矩分量和振子强度远远大于其他对称态下的跃迁矩分量和振子强度, 甚至大于单光子激发. 这不仅与分子的对称性有一定的关系, 而且应该是选择双光子跃迁能级的重要依据.
关键词:
全相对论量子力学
双光子激发
电偶极跃迁矩
振子强度 相似文献
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用密度泛函理论在B3LYP/6-311++g(d,p)基组水平上对Al2O3X2(X=H,D,T)分子的可能较低能量构型进行了几何优化.结果表明该分子的基态电子态和对称性为Al2O3X2(X=H,D,T)(1A′)Cs,计算了氢同位素分子及Al2O3X2(X=H,D,T)的电子能量E、定容热容CV和熵S.用电子振动近似方法计算了固体Al2O3的氢化热力学函数△H0,△S0,△G0,以及平衡压力与温度的关系.当Al2O3吸附氢(氘,氚)形成固体时,反应的氢氘氚排代效应的顺序为氚排代氘,氘排代氢,与钛等金属与氢及其同位素反应的氢氘氚排代效应的顺序相反.总体来说,这种排代效应都非常弱.随着温度的增加,这系列反应的氢氘氚排代效应趋于消失. 相似文献
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采用运动方程单双取代耦合团簇理论(EOM-CCSD)对XF3(X=N,P,As)的价层垂直离势(VIP)进行了系统计算,同时对称匹配团簇组态相互作用(SAC-CI)、外价层格林函数(OVGF)以及部分三阶近似(P3)方法也被应用到目前计算.与已有的实验结果比较表明:EOM-CCSD计算的价层垂直电离势整体上与SAC-CI结果相近,而优于OVGF和P3理论结果,在整个价层上,EOM-CCSD结果与实验值总体差距约0.2 eV, 在外价层这种差距相对较小,在内
关键词:
XF3(X=N;P;As)')" href="#">XF3(X=N;P;As)
垂直电离势
运动方程耦合团簇理论 相似文献
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在传统遗传算法的基础上提出了单母体遗传算法(single-parent genetic algorithm, SPGA),通过对母体团簇实施两种不同的变异操作对结构进行优化,给出了分子团簇结构优化的算法实现. 结合TIP3P模型势函数,研究了水分子团簇(H2O)n(n≤14)的稳定结构. 优化结构和已有理论及实验结果一致. 计算结果表明当n<8时,平均结合能随n增加较快;当n≥8时有小的起伏. n=4,8,10,12的团簇结构具有较高对称性,比较稳定.
关键词:
单母体遗传算法
水分子团簇
结构优化 相似文献
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将碳纳米管与纳米Al2O3-TiO2陶瓷粉末超声共混制备了碳纳米管/纳米Al2O3-TiO2复合粉末,测试了复合粉末在2—18GHz波段的电磁参数.研究表明:随着碳纳米管质量分数的增加,碳纳米管/纳米Al2O3-TiO2复合粉末的复介电常数和损耗角不断增大.当碳纳米管质量分数和厚度增加时,复合粉末对电磁波的反射率峰值先增加后减小,而谐振频率不断向低频移动.采用微弧等离子喷涂制备了7wt%碳纳米管/纳米Al2O3-TiO2复合吸波涂层,当厚度为1.5mm时,涂层最小反射率为-24.0dB,当厚度为2.0mm时,涂层小于-10dB的频带宽为3.60GHz,当温度为500℃高温时,1.0mm厚的涂层最小高温反射率为-12.2dB,小于-10dB频带宽为2.0GHz.复合涂层的实际厚度D与理论厚度d呈线关系:d=0.898D+0.515.
关键词:
等离子喷涂
碳纳米管
2O3-TiO2')" href="#">纳米Al2O3-TiO2
吸波性能 相似文献
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利用密度泛函理论研究了Aun(n=2,3,4)团簇与乙醇分子的吸附机理.研究结果表明:Aun(n=2,3,4)团簇分别能够吸附1到n个乙醇分子,生成Aun-(C2H6O)1-n配合物;Au4团簇吸附乙醇分子有多种构型,通过分析吸附能和Mulliken电荷分布,确定了4个乙醇分子的吸附顺序及相应的稳定构型;Aun(n=3,4)团簇在吸附最后一个乙醇分子时改变了前面Au—O成键的作用模式,而是选择Au—H成键;作为吸附主体的金团簇和被吸附的乙醇分子在吸附前后构型变化都很少,它们之间的吸附作用为弱相互作用.
关键词:
金团簇
乙醇分子
密度泛函理论 相似文献
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采用中频磁控溅射法制备了镱铒共掺Al2O3薄膜,铒镱掺杂浓度分别为0.3%,3.6%(摩尔分数,全文同).讨论了三价铒离子529nm和549nm光致发光的上转换机理.在291.8—573.3K温度区间测量了两绿上转换光谱荧光强度比的温度特性,拟合表达式为R=5.37exp(-738/T).366 K温度时灵敏度最大,为0.0039 K-1.结果表明镱铒共掺Al2O3薄膜适合作为小型、高温和高灵敏的光学温度传感材料.
关键词:
2O3薄膜')" href="#">镱铒共掺Al2O3薄膜
中频磁控溅射
上转换
荧光强度比 相似文献
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研究了通过有机金属化学气相沉积技术及单源分子前躯体方法制备的Ni/Al2O3纳米复合材料的氢吸附(存储). 在冷壁的有机金属化学气相沉积反应器中,通过降解Ni(acac)2粉末基底上的[H2Al(OtBu)]2制备的Ni/Al2O3纳米复合材料. 通过X射线粉末衍射、扫描电镜、透射电镜以及能量色散型X射线荧光光谱等技术表征该复合材料. 采用自制Sievert's设备研究该复合材料的氢吸附(存储),可以储存约2.9%(重量比)的氢. 相似文献
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Analytical potential energy function for the electronic states 2^∏1/2 and 2^∏3/2 of O^x2 (x=+1, -1)
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The splitting of potential energy levels for ground state X^2∏g of O^x2 (x = +1,-1) under spin-orbit coupling (SOC) has been calculated by using the spin-orbit (SO) multi-configuration quasi-degenerate perturbation theory (SO-MCQDPT). Their Murrell-Sorbie (M S) potential functions are gained, and then the spectroscopic constants for electronic states 2^∏1/2 and 2^∏3/2 are derived from the M S function. The vertical excitation energies for O^x2 (x = +1,-1) are v[O2+1^(2∏3/2→X^2∏1/2)] =195.652cm^-1, and v[O2^-1(2^∏1/2 →X^2∏3/2)] =182.568cm^-1, respectively. All the spectroscopic data for electronic states 2^∏1/2 and 2^∏3/2 are given for the first time. 相似文献
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Phosphors of nanoparticles YPXV1−XO4:Dy3+ (0?X?1) have been prepared by a citrate sol-gel method. X-ray diffraction, transmission electron microscope (TEM), scanning electron microscope (SEM) and photoluminescence excitation and emission spectra were utilized to characterize the phosphors. The results of XRD showed that a solid solution formed in YPXV1−XO4:Dy3+ phosphor series from X=0 to X=1 with zircon structure. TEM and SEM studies revealed that the obtained YPXV1−XO4:Dy3+ nanocrystals appeared to be spherical with some agglomeration and their sizes ranged from 30 to 80 nm. Upon short ultraviolet excitation, the optical properties of all the powder presented that the characteristic transitions of Dy3+ due to 4F9/2-6H15/2 (blue) and 4F9/2-6H13/2 (yellow) were detected. Besides this, in the system of YPXV1−XO4:Dy3+, the yellow-to-blue intensity ratio (Y/B) depended on the value of P/V greatly, with the increasing of X value and the decreased Y/B value. The phosphor found to yield white light when the value of X in the range of X=0.775-0.85, the optimum concentration for Dy3+ is 1 mol% of Y in the host, and the emission intensity increased with the annealing temperature. 相似文献
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采用溶胶-凝胶(sol-gel)工艺制备0.1 mol% Er3+掺杂Al2O3体系和SiO2-Al2O3复合体系粉末. 实验结果表明:5 mol%的SiO2复合加入Al2O3抑制γ→θ和θ→α相转变. 掺0.1 mol%Er3+:Al2O3体系粉末,900℃烧结,在1.47—1.63μm波段内光致发光(PL)谱为中心波长1.53 μm、半高宽56 nm的单一宽峰,1000—1200℃烧结,劈裂为多峰PL谱. 掺0.1 mol%Er3+:SiO2-Al2O3复合体系粉末,在高达1200℃烧结,仍保持中心波长1.53 μm的单一宽峰PL谱,由于—OH更完全的脱除,PL强度较900℃烧结Al2O3体系,SiO2-Al2O3复合体系均提高1个数量级.
关键词:
2-Al2O3复合体系')" href="#">SiO2-Al2O3复合体系
掺铒
溶胶-凝胶工艺
光致发光 相似文献
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In the present paper, phosphors with the composition Y3−x−yAl5O12:Bi3+x, Dy3+y were synthesized with solid state reactions. The luminescence properties of Bi3+ and Dy3+ in Y3Al5O12(YAG) and the energy transfer from Bi3+ to Dy3+ were investigated in detail. Bi3+ in YAG emits one broad band peaking at 304 nm which can be ascribed to the transition from excited states 3P0, 1 to ground state 1S0. Dy3+ in YAG emits two groups of peaks around 484 and 583 nm, respectively, which can be ascribed to the transitions from excited state 4F9/2 to ground states 6H15/2 and 6H13/2. The co-doping of Bi3+ enhances the luminescent intensity of Dy3+ by ∼7 times because Bi3+ can transfer the absorbed energy to Dy3+ efficiently. The mechanism of energy transfer was also discussed. 相似文献
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The equilibrium structure of flue gas SO2 is optimized using the density functional theory (DFT)/B3P86 method and CC-PV5Z basis. The result shows that it has a bent (C2v, X1A1) ground state structure with an angle of 119.1184°. The vibronic frequencies and the force constants are also calculated. Based on the principles of atomic and molecular reaction statics (AMIIS), the possible electronic states and reasonable dissociation limits for the ground state of SO2 molecule are determined. The potential functions of SO and 02 are fitted by the modified Murrell-Sorbie+c6 (M-S+c6) potential function and the fitted parameters, the force constants and the spectroscopic constants are obtained, which are all close to the experimental values. The analytic potential energy function of the SO2 (X1A1) molecule is derived using the many-body expansion theory. The contour liues are constructed, which show the static properties of SO2 (XIA1), such as the equilibrium structure, the lowest energies, the most possible reaction channel, etc. 相似文献