Utilization of surface plasmon resonance of Au/Pt nanoparticles for highly photosensitive ZnO nanorods network based plasmon field effect transistor

Hydrothermally processed highly photosensitive ZnO nanorods based plasmon field effect transistors (PFETs) have been demonstrated utilizing the surface plasmon resonance coupling of Au and Pt nanoparticles at Au/Pt and ZnO interface. A significantly enhanced photocurrent was observed due to the plasmonic effect of the metal nanoparticles (NPs). The Pt coated PFETs showed I_on/I_off ratio more than 3 × 10⁴ under the dark condition, with field-effect mobility of 26 cm² V⁻¹ s⁻¹ and threshold voltage of −2.7 V. Moreover, under the illumination of UV light (λ = 350 nm) the PFET revealed photocurrent gain of 10⁵ under off-state (−5 V) of operation. Additionally, the electrical performance of PFETs was investigated in detail on the basis of charge transfer at metal/ZnO interface. The ZnO nanorods growth temperature was preserved at 110 °C which allowed a low temperature, economical and simple method to develop highly photosensitive ZnO nanorods network based PFETs for large scale production.     

时间尺度上二阶线性动力学方程的一般解与Ulam稳定性

本文利用参数变易法研究了时间尺度上二阶变系数线性动力学方程的解与Ulam稳定性问题. 特别地,在不同的系数情形下建立了二阶常系数线性动力学方程的Ulam稳定性理论.     

石墨炔结构及性能的理论研究(英文)

石墨炔作为一种新的稳定的碳同素异形体,由于其独特的结构和性能,预计可广泛地应用于纳米材料及器件中.在本文中,我们采用B3LYP/6-31+G*理论研究了其结构参数、Wiberg键级以及芳香性.计算结果表明,所有的碳原子的p-电子参与形成了非定域的π-键,使得所有C—C键长平均化.苯环的核独立化学位移比乙炔形成的不等边六边形的更负,表明苯环的芳香性更强.该化合物的拓扑性质与Wiberg键级的计算结果也一致.另外,该化合物的LUMO(0.27 eV)带宽大于其HOMO(0.24 eV)的带宽,表明它应该是n-型材料.当采用对称性破缺方法重新对该化合物优化后,计算结果显示该化合物含有3.6个未成对电子,并具有一定的化学反应活性.     

乙炔与H2O分子之间的氢键结构与性质

采用B3LYP方法,在6-311++G水平上优化得到了H2O…C2H2氢键复合物的σ-n和H-π型两种稳定构型,并进行频率分析,讨论了相关自然键红外振动光谱的红移现象.采用NBO理论对σ-n和H-π氢键复合物形成过程中的电荷转移的类型进行了分析讨论.分子间的氢键相互作用能结果表明,σ-n型比H-π型氢键复合物更稳定.     

Inverse hydrogen bonds between SiH_4 and hydrides of Na,Mg and Be

The optimized geometries of the three complexes between MeHn (Me=Na,Mg,Be;n=1 or 2) and SiH4 have been calculated at the B3LYP/6-311++g**,MP2/6-311++g(3df,3pd) and MP2/aug-cc-pvtz levels,respectively.The red-shift inverse hydrogen bonds (IHBs) based on Si-H,an electron donor,were reported.The calculated binding energies with basis set super-position error (BSSE) correction of the three complexes are-5.98,-8.65 and-3.96 kJ mol-1 (MP2/6-311++g(3df,3pd)),respectively,which agree with the results obtained via M...     

On the catalytic mechanism of Pt 4+/? in the oxygen transport activation of N2O by CO

The two-state reaction mechanism of the Pt₄^+/− with N₂O (CO) on the quartet and doublet potential energy surfaces has been investigated at the B3LYP level. The effect of Pt₄ ⁻ anion assistance is analyzed using the activation strain model in which the activation energy (ΔΕ ^≠) is decomposed into the distortion energies (\Updelta E ¹ _\textdist ) (\Updelta E^{ \ne }_{\text{dist}} ) and the stabilizing transition state (TS) interaction energies (\Updelta E ¹ _\textint ) (\Updelta E^{ \ne }_{\text{int}} ) , namely \Updelta E ¹ = \Updelta E ¹ _\textdist + \Updelta E ¹ _\textint \Updelta E^{ \ne } = \Updelta E^{ \ne }_{\text{dist}} + \Updelta E^{ \ne }_{\text{int}} . The lowering of activation barriers through Pt₄ ⁻ anion assistance is caused by the TS interaction \Updelta E ¹ _\textint \Updelta E^{ \ne }_{\text{int}} (−90.7 to −95.6 kcal/mol) becoming more stabilizing. This is attributed to the N₂O π*-LUMO and Pt d HOMO back-donation interactions. However, the strength of the back-donation interactions has significantly impact on the reaction mechanism. For the Pt₄ ⁻ anion system, it has very significant back-bonding interaction (N₂O negative charge of 0.79e), HOMO has 81.5% π* LUMO(N₂O) character, with 3d orbital contributions of 10.7% from Pt₍₃₎ and 7.7% from Pt₍₇₎ near the ⁴TS4 transition state. This facilitates the bending of the N₂O molecule, the N–O bond weakening, and an O⁻(²P) dissociation without surface crossing. For the Pt₄ ⁺ cation system, the strength of the charge transfer is weaker, which leads to the diabatic (spin conserving) dissociation of N₂O: N₂O(¹∑⁺) → N₂(¹∑_g⁺) + O(¹D). The quartet to doublet state transition should occur efficiently near the ⁴TS1 due to the larger SOC value calculated of 677.9 cm⁻¹. Not only will the reaction overcome spin-change-induced barrier (ca. 7 kcal/mol) but also overcome adiabatic barrier (ca. 40.1 kcal/mol).Therefore, the lack of a thermodynamic driving force is an important factor contributing to the low efficiency of the reaction system.     

4-羟基苯甲酰肼的红外光谱研究

基于密度泛函理论(Density functional theory,DFT)B3LYP/6-311+G(d,p)及二级微扰理论(Second-order Mller-Plesset,MP2)MP2/6-311+G(d,p)对4-羟基苯甲酰肼分子进行了构型优化,得到了该分子的稳定几何构型,在此基础上对其频率进行了计算和指认,与4-羟基苯甲酰肼的实验谱图比较分析发现,真空分子的羟基、胺基及CH的特征振动频率与实验值相差较大。因此在单晶数据的基础上,增加一个氨气分子,模拟相邻分子对该分子的影响,MP2的计算结果表明,羟基的振动频率与实验值吻合很好,说明相邻分子之间的相互作用不能忽略以及MP2理论在解释该类分子的振动光谱方面具有较高的可靠性。     

3类图完美匹配的数目

图的完美匹配计数问题是匹配理论研究中的一个重要课题，此问题有很强的物理学和化学背景．但是，一般图的完关匹配计数问题却是NP-困难的．用划分、求和、再递推的方法给出了三类特殊图完美匹配数目的计算公式．     

激发态1，2-二硫环丁烯去活性和异构化机理的理论研究

运用完全活性空间多组态CASSCF方法研究了激发态1,2-二硫环丁烯（1,2-Dithiete）势能面交叉机理．自旋．轨道耦合（SOC）常数采用完全Pauli-Breit旋轨耦合算符（包括单电子和双电子项）进行计算,其强度为198．37或211．35cm^-1,对不同自旋态跃迂起着重要作用．研究结果表明：光激发1,3-dithiol-2-one导致形成主要产物trans—dithioglyoxal（Trans-MinS0）和次级产物thiolthioketene．计算与实验观察结果一致．