羟基水团簇OH~n(H_2O)_3(n=0,±1)的比较研究

使用粒子群优化算法结合从头算方法得到了羟基水团簇OH~n(H_2O)_3(n=0,±1)的低能结构,并对考虑零点能后最稳定的团簇的成键、分子轨道和红外性质进行了对比研究.对最高占据轨道进行键序分析表明:阴离子团簇中的外来电子占据了羟基中的氧原子的空轨道,自由基型团簇中的部分电子从水分子转移到了羟基上,阳离子团簇中形成了很强的氧氧键.对这些团簇的红外谱进行了计算和分析,这将为相关实验提供理论参考.     

[Fe_3O(Ala)_6(H_2O)_3](ClO_4)_7和[Fe_3O(Gly)_6(H_2O)_3](NO_3)7·3H_2O的顺磁共振谱及变温磁化率研究

本文通过对 [Fe3 O(Ala) 6(H2 O) 3 ](Cl O4) 7和 [Fe3 O(Gly) 6(H2 O) 3 ](NO3 ) 7· 3H2 O的 ESR谱的解析及变温磁化率的研究 ,得出它们的 ESR谱具有各向同性的特点 ;朗德因子分别为 2 .0 19和 1.997;两种配合物中铁离子间有反铁磁相互作用     

∧超核_∧~9Be、_(∧∧)~6He和_(∧∧)~(10)Be的动力学结构

本文在α集团模型下,利用谐振子基展开和广义Talmi-Moshinsky变换,完成了对Λ超核_Λ~9Be、_(ΛΛ)~6He和_(ΛΛ)~(10)Be能谱的变分计算.借助统一的α-α、Λ-Λ势和修正的Λ-α势,使_Λ~9Bc、_(ΛΛ)~6He和_(ΛΛ)~(10)Be的能级得到自洽的描述.此外,对上述三个Λ超核的结构和粒子间的关联也作了研究和分析,得到一些有意义的结果.     

含Al(PO_3)_3氟磷酸盐玻璃的光学及其它物理性质

氟磷玻璃作为光学玻璃及激光工作物质,正在获得应用。在研究Al(PO_3)_3系统玻璃的生成及结构的基础上,本文研究了光学及其它物理性质。Al(PO_3)_3含量低的氟磷玻璃,网络结构受到极大的破坏,处于破坏区,性质变化及各种氟化物对性质的影响与处于破坏区的氧化物玻璃相似。LiF、MgF_2和AlF_3等氟化物的特殊作用在物理性质变化方面也得到反映。同时,与硅酸盐和硼酸盐等玻璃生成体含量高的玻璃比较,静电吸引力对Al(PO_3)_3含量低的氟磷玻璃的性质变化起着更大的作用。文中表示所研究玻璃在n_d～v_d图中的位置,给出低Al(PO_3)_3含量玻璃中的部分性质,与文献数据进行比较,并把部分性质的变化与Al(PO_3)_3含量相联系.     

(ZnX)_3(X=S、Se和Te)量子点配体效应的密度泛函理论研究

采用密度泛函理论研究了一系列含磷配体(OPH_3、OPH_2Me、OPHMe_2和OPMe_3)对量子点(ZnX)_3(X=S、Se、Te)结构和性质的影响.Zn原子与配体中的O原子生成新的Zn-O配位键,使量子点的结构、吸附能、电荷分布、吸收光谱和HOMO-LUMO轨道等性质随着配体中甲基数目逐渐增多发生规律性的改变.计算结果表明:有机配体三甲基氧膦(OPMe_3)是阻止小尺寸(ZnX)_3量子点聚集,保护此类量子点的较为有效的配体.     

某些分子电子结构的SCM-DV-X_α方法计算I.C_r(CO)_6、V(CO)_6和CH_3OH分子的电离能计算

本文从具体计算的角度简要介绍了从1982年发展起来的SCM-DV-X_α方法。用此法计算了C_r(CO)_6、V(CO)_6的电离能。并用SCC-DV-X_α方法计算了CH_3OH的电离能,得到的结果均与实验符合较好。     

La0.3Ca0.7Mn1-xWxO3(x=0.04,0.08,0.12)体系的电子自旋共振谱研究

用固相反应法制备了La0.3Ca0.7Mn1-xWxO3(x=0.04,0.08,0.12)多晶材料,测量了样品的p～T曲线及ESR谱,对ESR谱的归一化强度和线宽进行了研究.结果表明:当x≤0.08时,ρ～T曲线出现弯折点,体系出现电荷有序(CO)相,体系随温度降低发生顺磁(PM)-电荷有序(CO)-反铁磁(AFM)变化;当x=0.12时,ρ～T曲线没有出现弯折点,CO相融化,自旋序主要是顺磁(PM),但存在CO相的残留.x≤0.08样品的线宽在高于Tco的温区几乎不随温度变化,体系处在顺磁态,铁磁关联较弱;在低于Tco的温区,电子的局域化程度增强,线宽随温度的降低而增加.     

用ARUPS研究在Cs/Ru(1010)面上的CO分子轨道对称性

用同步辐射角分辨紫外光电子能谱对CO与Cs在Ru(1010)面上共吸附的研究结果表明,由于Cs的强烈影响,CO的分子轨道重新排列.对应清洁表面上CO分子的(5σ+1π)轨道的7.5eV谱峰分裂成两个,分别处于6.3和7.8eV,6.3eV谱峰关于一个垂直于Ru(1010)面而平行于〈0001〉晶向的镜象面反对称性. 关键词：     

多金属氧酸盐α-Na_6H〔GeW_9Fe_3(H_2O)_3O_(37)〕·16H_2O的合成和光谱

合成了多金属氧酸盐 α- Na6H〔 Ge W9Fe3 (H2 O) 3 O3 7〕· 16 H2 O,通过元素分析、红外、紫外、光电子能谱、极谱和穆斯堡尔谱等手段进行了表征 ,并讨论和研究了该配合物的谱学性质     

Er_xY_(1-x)Al_3(BO_3)_4晶体的生长和光谱性质

采用助熔剂法生长出了掺杂均匀的Er_xY_(1-X)Al_3(BO_3)_4厘米级优质单晶.测定了晶体的吸收、激发光谱.用Judd_Ofelt理论计算了晶体中Er~(3+)的十一条谱带的振子强度(ρ_(ad)和ρ_(md)以及Er~(3+)的强度参数Q_λ(λ-2、4、6).并由此计算了Er~(3+)不同能级之间跃迁的爱因斯坦自发辐射系数A_r、辐射寿命r、荧光分支比β_3以及积分发射截面Σ.根据这些参数讨论了在EYAB晶体中可能实现激光输出的通道.     

金刚石材料的ESR研究

用ESR方法对照研究了中国出产的五颗天然金刚石单晶,四颗人造金刚石单晶和两个化学沉积金刚石膜(CVD)等固体材料.发现I_b型天然金刚石中有四种a_N各向异性的N-中心自由基和一种C-中心自由基;而I_aB3型的未配对电子定域在N3型杂质中心的π^*反键轨道上;I_b型人造金刚石含有少量Ni,Fe等顺磁元素造成ESR线增宽,仅可观察到二重或三重裂分;在不同金刚石膜中.c-中心自由基的浓度可以相差很大.而低浓度的N-中心自由基的浓度相对变化较小;所观察到的C-中心自由基的两个卫星峰(a_H=7.2×10^-4T)是金刚石膜中¹H存在的直接证据.结果表明ESR方法是金刚石及类金刚石材料的一种快捷而有效的表征方法.     

Fe（CO）5双色共振增强多光子电离研究

利用超声分子束、强激光多光子电离和飞行时间质谱探测装置研究了Fe(CO)_5分子在355nm、532nm和355nm+532nm单、双色激光作用下的多光子电离质谱.实验结果证明了双色激光的共振增强电离作用.由飞行时间质谱的展宽峰型结构估算了Fe(CO)_5等分子的光解离寿命与Fe~+和Fe(CO)_5离子分子反应截面.     

Photoemission from Co on Pt(111) using synchrotron radiation in the range 40 eV ω 150 eV

Photoelectron spectra for CO adsorbed on the (111)-face of Pt have been measured using synchrotron radiation of energy 40 eV ω 150 eV. A dramatic increase of the molecular orbital (MO) intensity relative to the intensity of the Pt 5d valence band (VB) is observed for ω > 100 eV, to a ratio at that is a factor of three higher than at . The energy variation of the Pt 5d VB photoemission peak intensity has been derived independently in the 40–200 eV range from measurements on clean Pt. The 5d peak intensity is found to decrease steeply (by more than an order of magnitude) between 100 and 150 eV. The observed increase of the MO peak intensity relative to that of the 5d VB is attributed to this cross-section effect. The Pt VB peak nearest the Fermi energy which is mainly t_2g in character, is found to decrease in intensity on adsorption of CO. In the present case synchrotron radiation in the ω > 100 eV range appears to be especially valuable for studies of adsorbates.     

十二羰基三铁与DNA相互作用的紫外和荧光光谱研究

采用紫外-可见吸收光谱、荧光光谱等法研究了十二羰基三铁簇合物与小牛胸腺DNA的相互作用.在簇合物存在下,DNA的紫外吸收光谱产生了明显的增色效应.荧光光谱表明簇合物的荧光强度随DNA的加入其荧光强度增加,说明簇合物与DNA之间发生了插入作用.     

Auger spectra of carbon monoxide chemisorbed on Pt(111) and Cu(111)

The Auger spectra of carbon monoxide adsorbed on Pt(111) and Cu(111) are compared. The characteristic features now regarded as a fingerprint of this adsorbed species are observed, even for the weakly adsorbed CO on copper which gives complex X-ray photoelectron spectra. No coverage dependence of the spectra was observed on either substrate. The C lsVV spectrum of CO/Cu(111) is dominated by transitions involving the “screening” electron in the 2π orbital.     

A density functional theory study on the adsorption of CO and O2 on Cu-terminated Cu2O （111） surface

The adsorptions of CO and 02 molecules individually on the stoichiometric Cu-terminatcd Cu20 （111） surface are investigated by first-principles calculations on the basis of the density functional theory. The calculated results indicate that the CO molecule preferably coordinates to the Cu2 site through its C atom with an adsorption energy of-1.69 eV, whereas the 02 molecule is most stably adsorbed in a tilt type with one O atom coordinating to the Cu2 site and the other O atom coordinating to the Cul site, and has an adsorption energy of -1.97 eV. From the analysis of density of states, it is observed that Cu 3d transfers electrons to 2π orbital of the CO molecule and the highest occupied 5σ orbital of the CO molecule transfers electrons to the substrate. The sharp band of Cu 4s is delocalized when compared to that before the CO molecule adsorption, and overlaps substantially with bands of the adsorbed CO molecule. There is a broadening of the 2π orbital of the 02 molecule because of its overlapping with the Cu 3d orbital, indicating that strong 3d-2π interactions are involved in the chemisorption of the 02 molecule on the surface.     

Structures,electronic properties and reaction paths from Fe(CO)5 molecule to small Fe clusters

The geometries, electrical characters and reaction paths from Fe(CO)₅ molecule to small Fe clusters were investigated by using all-electron density functional theory. The results show that in the decomposition process of pentacarbonyl-iron, Fe(CO)₅ molecule prefers to remove a carbon monoxide and adsorb another Fe(CO)₅ molecule to produce nonacarbonyldiiron Fe₂(CO)₉ then Fe₂(CO)₉ gradually removes carbon monoxide to produce small Fe clusters. As It can be seen from the highest occupied molecule orbital–lowest unoccupied molecule orbital gap curves, the Fe(CO)_n=3,?and?5 and Fe₂(CO)_n=3,?7?and?9 intermediates have higher chemical stability than their neighbors. The local magnetic moment of the carbon monoxide is aligning anti-ferromagnetic. The effect of external magnetic field to the initial decomposition products of Fe(CO)₅ can be ignored.     

Cluster modelling of core electron photoabsorption of CO adsorbed on Cu(100)

Quantum chemical calculations of discrete and continuum near-edge X-ray absorption spectra of carbon monoxide adsorbed on Cu(100) are presented and discussed. The surface is modelled by clusters using one-electron effective core potentials for distant atoms, allowing cluster sizes up to 50 atoms to be treated. The employed theoretical approach, the direct, atomic orbital, static exchange technique, implementing the independent-particle approximation close to the basis set limit, is shown to provide good representations of the near edge X-ray absorption spectra both for free and adsorbed CO. The experimental observations of reduction of energy and intensity of the first π1 resonance and a compression of the discrete part of the spectra are reproduced by the calculations. The origin of these effects is discussed.     

抗氧化剂抗脂质过氧化机制的ESR研究

以NADH诱导的心肌线粒体损伤体系为模型,在体外用ESR研究了谷胱甘肽(GSH)、超氧化物歧化酶(SOD)及辣根过氧化物酶(HRP)的抗氧化机制.结果表明,低浓度的GSH可部分抑制体系中自由基的生成;SOD与HRP以适当比例共同作用,可完全抑制体系中自由基的生成,较好地防止脂质过氧化的发生.     

CO在Ni(100)表面活化及硫中毒机理的ASED—MO研究

本文应用原子交迭和电子离域-分子轨道(ASED-MO)理论,研究了CO在Ni(100)表面活化及硫中毒机理。计算结果表明,CO顶位吸附比四度中心位吸附有更大的结合能。当CO分子被吸附于顶位时,其2π反键轨道将获得0.72个电子,解离能将从自由CO分子的11.1eV降到2.15eV。当吸附于四度中心位时,2π轨道将获得1.22个电子,解离能进一步降到1.85eV。由此看来,吸附于四度中心位的CO分子将具有更大的活性。当Ni(100)面上同时存在S原子吸附时,不同相对位置CO吸附结合能的计算结果表明,一个吸附S原子将“堵塞”四个最近邻顶位和四个最近邻中心位对CO的吸附作用,而对更远一些的吸附位则没有什么影响。这些结果支持了被吸附S原子对CO吸附的影响主要是近程性“结构效应”的观点。被吸附S原子的上述“堵塞”作用,吸附S原子后CO激活吸附位的减少,及可能存在的其它因素,构成了Ni表面的硫中毒。 关键词：