M_6^(0,±)(M=Os,Ir,Pt)团簇结构与性质的密度泛函理论研究

采用密度泛函理论(DFT)中的杂化密度泛函(B3LYP)方法,在LANL2DZ基组水平上对M06,±(M=Os,Ir,Pt)团簇的各种可能构型进行了几何结构优化,得出各团簇的最稳定构型,并对其能量、振动频率、热力学性质、核独立化学位移(NICS)和极化率进行了理论研究.结果表明,M06,±(M=Os,Ir)团簇的基态都是三棱柱结构,Pt-6团簇的基态是平面三角形结构;M06,±(M=Os,Ir,Pt)团簇生成焓都为负值,热力学上是稳定的;NICS值都为负值,表明M06,±(M=Os,Ir,Pt)团簇都具有芳香性,其中Os-6团簇的芳香性最强;从光谱分析来看,Os6的IR和Raman谱的较强吸收峰的个数最多,Ir6的IR和Raman谱的最强吸收峰都只有一个,IR最强吸收峰在137.0和143.5 cm-1之间,Raman谱最强的吸收峰位于169.5 cm-1处;Pt6的IR和Raman谱的最强吸收峰分别位于50.2和194.7 cm-1处.

(Pt_nMn)^(±,0)(n=1～5)掺杂团簇结构与磁性的密度泛函研究

采用密度泛函理论(Density Function Theory)中的B3LYP方法,在Lanl2dz赝势基组水平上对(PtnMn)±,0(n=1~5)团簇的几何构型进行了全优化,并对基态的能级以及磁性进行了研究.结果表明:PtMn掺杂团簇的自旋多重度比较高,这种性质跟纯Mn团簇相似.并且发现一般情况下Mn原子参与成键数越多,结构越稳定,在成键数相同的情况下,成键的平均键长越短越稳定;其次(PtnMn)±,0团簇的所有稳定结构都表现为铁磁性耦合;掺杂一个Mn原子后的团簇磁性大大增强,磁矩主要来源于未满的d壳层电子,且Mn原子上的局域磁矩远大于Pt原子.随着Pt原子个数的增加,Mn原子的局域磁矩变化不大,但团簇的总磁矩渐渐增大.

Pt_nNi_m(n+m=6,n、m≠0)团簇结构与性质的理论研究

采用密度泛函理论(DFT)中的杂化密度泛函B3LYP方法在Lanl2dz基组水平上对PtnNim(n+m=6,n、m≠0)团簇的各种可能构型进行了几何结构优化,得出了它们的基态构型,并对其能量、热力学性质、核独立化学位移、光谱和极化率进行了理论研究.研究结果表明,PtNi5、Pt2Ni4和Pt3Ni3团簇的基态结构都为四角双锥结构,Pt4Ni2和Pt5Ni团簇的基态结构分别是戴帽三角双锥和三角锥戴四边形结构;PtnNim团簇的生成焓都为负值,表明团簇在热力学上是稳定的;由核独立化学位移值可得,PtNi5团簇具有反芳香性,Pt2Ni4和Pt5Ni团簇具有芳香性;从光谱分析来看,Pt3Ni3团簇的IR较强吸收峰的个数最多,PtNi5团簇IR和Raman、Pt2Ni4团簇的IR、Pt3Ni3和Pt4Ni2团簇的Raman只有一个强吸收峰值,Pt5Ni团簇的峰值只出现在频率较大的位置,频率小的位置几乎为零.

PtnNim(n+m≤5,n,m≠0)团簇结构与性质的密度泛函理论研究

采用密度泛函理论(DFT)中B3LYP方法,在Lanl2dz水平下对Pt_nNi_m(n+m≤5,n,m≠0)团簇进行了结构优化,预测它们的基态几何结构,并对基态结构的平均结合能、磁性以及五个原子团簇的振动频率和光谱进行了分析.结果表明:Pt_nNi_m(n+m≤5,n,m≠0)团簇的基态结构趋向于立体结构,三个原子团簇的基态结构都为三角形,四个原子团簇的都为四面体,五个原子团簇都为船型;PtNi_n(n=2-4)团簇都具有弱的反铁磁性,其他团簇都呈铁磁性,并且我们所计算的Pt/Ni合金团簇的磁性具有Ni纯团簇的特征.它们的磁矩分为两个阶段:当2≤n+m≤4时团簇的磁矩为2μ_B,n+m=5时团簇的磁矩突增到4μ_B,且五个原子团簇的9个振动模式都既具有红外活性又具有拉曼活性.

关于幼儿识字教育的探索

兴趣是学习的原动力，采用灵活多样教育方式让幼儿识字，不仅提高了识字质量和效率，也帮助幼儿扩大了认知社会的信息量。

Pt_n^(0,±)(n=2～4)团簇的结构和稳定性的密度泛函理论研究

采用密度泛函理论(Density Function Theory,DFT)中的B3LYP和B3PW 91方法,在LanL2DZ赝势基组水平上对Ptn0,±(n=2~4)团簇的几何构型和稳定性进行了研究,主要从振动频率、能级、解离能3个方面进行了分析.研究表明:铂三聚物的中性、阴离子和阳离子最稳定结构都为等腰三角形;四聚物的中性、阴离子的最稳定结构都是二面体,阳离子则是正四面体结构最稳定.所计算的结果都与实验值相符合.

结合太阳能发电技术研究培养大学生科技创新能力

太阳能发电技术的研究作为开发新能源首选方法之一,具有技术含量高、知识面宽广、科技创新性强等特点,是培养大学生科技创新能力的优选途径。本文将太阳能发电技术引入教学、开展科技创新活动、校企合作等方式来进行大学生科技创新能力的培养。通过太阳能发电技术的研究和实验,可使大学生的实践及创新能力均有较大幅度的增强。

现代高校如何构建良好的师生关系

高校师生关系是高校中最主要的人际关系,师生关系的质量直接影响教育教学的成效和学生的身心发展,本文分析了现代高校师生关系不和谐的原因,并提出了构建和谐师生关系的几条途径,从而达到不断提高教学质量的目的。

有限元法在表面波等离子体中的数值模拟应用

工业用平板型表面波等离子体(SWP)源具有大面积、高密度、高活性等优良性能,其建造之前必须进行结构优化,而对表面电磁波的数值模拟,可以辅助其优化设计。基于有限元法(FEM),采用AnsoftHFSS模拟软件,数值仿真了大面积矩形SWP源的电磁场空间分布。研究了开槽天线激发表面波场的特性,得出了表面波场的空间分布,与理论分析和实验结果进行了对比,解释了表面波放电的实验现象。研究结果表明在石英-等离子体界面有表面电磁波存在,且分布均匀。研究成果为大面积高效等离子体工艺的产业应用提供建议,也为下一代超大面积SWP源的成功建造提供了有益借鉴。

Ionization process and distinctive characteristic of atmospheric pressure cold plasma jet driven resonantly by microwave pulses

In the present study,a coaxial transmission line resonator is constructed,which is always capable of generating cold microwave plasma jet plumes in ambient air in spite of using argon,nitrogen,or even air,respectively.Although the different kinds of working gas induce the different discharge performance,their ionization processes all indicate that the ionization enhancement has taken place twice in each pulsed periods,and the electron densities measured by the method of microwave Rayleigh scattering are higher than the amplitude order of 10^(18)m^(-3).The tail region of plasma jets all contain a large number of active particles,like NO,O,emitted photons,etc,but without O_(3).The formation mechanism and the distinctive characteristics are attributed to the resonance excitation of the locally enhanced electric fields,the ionization wave propulsion,and the temporal and spatial distribution of different particles in the pulsed microwave plasma jets.The parameters of plasma jet could be modulated by adjusting microwave power,modulation pulse parameters(modulation frequency and duty ratio),gas type and its flow rate,according to the requirements of application scenarios.

Pulsed microwave-driven argon plasma jet with distinctive plume patterns resonantly excited by surface plasmon polaritons

Atmospheric lower-power pulsed microwave argon cold plasma jets are obtained by using coaxial transmission line resonators in ambient air.The plasma jet plumes are generated at the end of a metal wire placed in the middle of the dielectric tubes.The electromagnetic model analyses and simulation results suggest that the discharges are excited resonantly by the enhanced electric field of surface plasmon polaritons.Moreover,for conquering the defect of atmospheric argon filamentation discharges excited by 2.45-GHz of continued microwave,the distinctive patterns of the plasma jet plumes can be maintained by applying different gas flow rates of argon gas,frequencies of pulsed modulator,duty cycles of pulsed microwave,peak values of input microwave power,and even by using different materials of dielectric tubes.In addition,the emission spectrum,the plume temperature,and other plasma parameters are measured,which shows that the proposed pulsed microwave plasma jets can be adjusted for plasma biomedical applications.

Characteristic plume morphologies of atmospheric Ar and He plasma jets excited by a pulsed microwave hairpin resonator

Different discharge morphologies in atmospheric Ar and He plasmas are excited by using a pulsed microwave hairpin resonator. Ar plasmas form an arched plasma plume at the opened end of the hairpin, whereas He plumes generate only a contracted plasmas in between both tips of metal electrodes. Despite this different point, their discharge processes have three similar characteristics：（i） the ionization occurs at the main electrode firstly and then develops to the slave electrode,（ii） during the shrinking stage the middle domain of the discharge channels disappears at last, and（iii） even at zero power input（in between pulses） a weak light region always exists in the discharge channels. Both experimental results and electromagnetic simulations suggest that the discharge is resonantly excited by the local enhanced electric fields. In addition, Ar ionization and excitation energies are lower than those of He, the effect of Ar gas flow is far greater than that of He gas, and the contribution of accelerated electrons only locates at the domain with the strongest electric fields. These reasons could be used to interpret the different characteristic plume morphologies of the proposed atmospheric Ar and He plasmas.

Observation of Hot Electrons in Surface-Wave Plasmas Excited by Surface Plasmon Polaritons

The electron energy distribution functions(EEDFs)are studied in the planar-type surface-wave plasma(SWP)caused by resonant excitation of surface plasmon polaritons(SPPs)using a single cylindrical probe.Sustained plasma characteristics can be considered as a bi-Maxwellian EEDF,which correspond to a superposition of the bulk low-temperature electron and the high-energy electron beam-like part.The beam component energy is pronounced at about 10 eV but the bulk part is lower than 3.5 eV.The hot electrons included in the proposed plasmas play a significant role in plasma heating and further affect the discharge chemistry.

气体压强及表面等离激元影响表面波等离子体电离发展过程的粒子模拟

基于表面等离激元(SPP)的表面波等离子体(SWP)源,具有高密度、低温度及高产率等优异性能,其应用在电子器件微纳加工、材料改性等领域.但由于SPP激励SWP放电的电离过程难于用理论分析和实验测量描述,因而SWP源均匀稳定产生的电离发展过程一直未研究清晰.本文以SWP放电的数值模拟为研究手段,采用等离子体与电磁波相互作用的粒子模拟(PIC)方法,结合蒙特卡罗碰撞(MCC)方法处理碰撞效应的优势,研究气体压强影响电离过程的电磁能量耦合机理.模拟结果表明SWP的高效产生是SPP的局域增强电场致使,气体压强能够改变波模共振转换的出现时刻而影响了SWP的电离发展过程.本文的研究成果展示了SPP维持SWP放电的电离过程,可为下一代米级SWP源的参数优化提供设计建议.