激光溅射Cu等离子体与气相C2H5OH团簇的反应

用激光溅射-分子束技术研究了气相中Cu的等离子体与乙醇分子团簇的反应.观察到三种团簇正离子Cu＋(C2H5OH)n、CuO＋(C2H5OH)n、H＋(C2H5OH)n和三种团簇负离子(C2H5OH)nC2H5O－、(C2H5OH)n(H2O)OH－、(C2H5OH)n(H2O)2OH－(n≤12).详细考察了在不同的载气压力下激光烧蚀等离子体作用于脉冲分子束， 以及在一定的压力下等离子体作用于分子束不同位置时，对团簇产物种类和团簇尺寸大小的影响.分析了Cu＋(C2H5OH)n、CuO＋(C2H5OH)n、H＋(C2H5OH)n、(C2H5OH)nC2H5O－、(C2H5OH)n(H2O)OH－、(C2H5OH)n(H2O)2OH－等团簇的产生机理.     

激光溅射Cu等离子体与气相CH3CN团簇的反应

The gas phase reaction of Cu plasma and acetonitrile clusters is studied by the laser ablation-molecular beam（LAMB） method. Four series of clustered complex ions Cu+（CH3CN）n, CH2CN+（CH3CN）n,H+（CH3CN）n and CH3CHCN+（CH3CN）n are observed. Interestingly,the species and sizes of the product clusters vary observably when the plasma acts on the different parts of the pulsed acetonitrile molecular beam. When the laser ablated Cu plasma acts on the head of the beam,the metal acetonitrile complex clusters Cu+（CH3CN）n together with protonated acetonitrile clusters H+（CH3CN）n and deprotonated acetonitrile clusters CH2CN+ （CH3CN）n are domain,while the plasma acts on the middle of the beam. However,CH2CN+（CH3CN）n and H+（CH3CN）n along with the clusters CH3CHCN+（CH3CN）n turn out to be the main resulting clusters. By comparing the intensities and the cluster sizes of CH3CHCN+（CH3CN）n with H+（CH3CN）n and CH2CN+（CH3CN）n,the formation of CH3CHCN +（CH3CN）n is contributed to the intracluster ion-molecule reaction of acetonitrile clusters.     

激光溅射Ni等离子体与气相CH3OH团簇的反应

The gas phase reaction of Ni plasma and methanol clusters is studied by the laser ablation-molecular beam（LAMB） method. Five species of clustered complex ions Ni+（CH3OH）n,NiO+（CH3OH）n,H+（CH3OH）n,H3O+（CH3OH）n,CH3O-（CH3OH）n（n≤25）are observed. Interestingly,the species and sizes of the product clusters vary observably when the plasma acts on the different parts of the pulsed methanol molecular beam. When the laser ablated Ni plasma acts on the head and tail of the beam,the metal methanol complex clusters Ni+（CH3OH）n and the oxidation clusters NiO+（CH3OH）n（n=1-15）together with protonated methanol clusters H +（CH3OH）n are domain. While the plasma acts on the middle of the beam,however,Ni+（CH3OH）1-2 and H+（CH3OH）n along with the mixed methanol-water clusters H3O+（CH3OH）n（n=15-25）turn to be the main resulting clusters. By comparing the intensities and the cluster sizes of NiO+（CH3OH）n with Ni+（CH3OH）n,the formation of NiO+（CH3OH）n is contributed to the intracluster demethanation reaction of Ni+（CH3OH）n and evaporation of several methanol molecules. As the H3O+（CH3OH）n is observed only when the plasma acts on the high density part of the beam,and their intensities are only 0. 5% of the protonated methanol molecule,it is concluded that the species are partially due to the recombination of H+（CH3OH）n and water,which come from the plasma-molecule reaction.     

激光等离子体中超金属氧化物离子LiZnO+的产生

作为一般规律 ,在一些具有热力学稳定性的氧化物分子中 ,氧原子周围共价电子数为 8.自从发现 Li3O和 Li4 O分子以来 ,这类超过 9个或更多共价电子的含金属团簇小分子呈现出来的特殊化学计量比和热力学稳定性引起人们的关注 ,人们称其为超共价分子 (Hypervalent Molecules)或超金属分子(Hypermetallic Molecules) [1～ 4 ] .目前 ,在实验上已发现了 Mn O,Mn S及 Mn C(M=Li,Na,K,Mg;n≥ 3 )等一系列超金属分子 ;在理论上 ,从头计算法已可计算出超金属分子的结构及其稳定性 ,使人们对这些超金属分子的产生与结构有一定的认识 .然而 ,由…     

固体无机样品的激光等离子体质谱分析

激光等离子体质谱是一种新颖的质谱分析手段，具有灵敏度高，分析速度快，分析范围广，分析结果准确性高等优点。本文介绍了在自制的激光离子体源飞行时间质谱计上，有关催化剂，铝箔，活性碳，岩石等固体无机样品的质谱分析结果，显示了激光等离子体质谱的优越性与广泛的应用价值。     

CnB-的激光等离子体产生与质谱分析

Time-of-flight mass spectrum of C_nB~- has been recorded on a selfbuilt instrument with laser vaporization of tetraphenylboron sodium. By analysis of the com-position of the anions, it is found that number of the boron atoms in any of these ions equals to the number of the charges carried by the anion, and the sum of the numbers of the carbon and boron atoms in these species are always the odd numbers. The experimental results show that boron atom has a strong tendency to attract an electron so that those C_nB~- will have similar electronic structures as C_n, and carbon clusters with odd members are always more stable than their even neighbors.     

C_πB~-的激光等离子体产生与质谱分析

随着“足球烃”C_(60)及其他“球碳烃”的发现,以及对它们奇妙的结构与化学行为的不断揭示,碳原子簇的产生与研究已成为当前化学界的一个热门课题.Smalley等最近又将C_(60)中的一个碳原子以硼原子取代,成为Lewis酸,使这方面的研究更加深入。近二年来,我们在自制的装置上对碳原子簇的结构作了较为充分的研究后,又以独特的方式产生了链状构型的C_nB~-,记录了它们的负离子质谱。     

激光溅射-分子束法研究镁、铝离子与乙腈分子的气相化学反应

利用激光溅射-分子束技术研究了Mg+、 Al+与乙腈分子的气相团簇反应.根据反射式飞行时间质谱检测的结果发现, Mg+、 Al+与乙腈分子反应形成不同尺寸的团簇离子产物,其中Al+与(CHCN)n的结合数n=1～10,而Mg+与(CHCN)n的结合数n=1～5. Al+(CHCN)n、 Mg+(CHCN)n团簇离子产物的强度分布都存在明显的强度间隙现象. Al+与(CHCN)n进行缔合时,出现了两个强度间隙;而Mg+与(CHCN)n进行缔合时,则只存在一个强度间隙. Al+的第一强度间隙在n=4～5,第二强度间隙在n=6～7;而Mg+的强度间隙在n=2～3.     

钇钡铜氧超导材料的激光等离子体质谱研究

尽管金属氧化物高温超导材料的发现及“超导热”的兴起己有五年多的历史,有关的研究仍在不断发展与深化.近年的研究发现,以激光蒸发可以沉积出高质量的金属氧化物的超导薄膜.Balooch 等以波长为1.06μm 的长脉冲激光作用于YBa_2Cu_3O_(7-x)(YBCO)样品,记录了所产生的中性物种的飞行时间质谱.最近我们在自制的仪器上记录了YBCO     

Synthesis and Isolation of Titanium Metal Cluster Complexes and Ligand-Coated Nanoparticles with a Laser Vaporization Flowtube Reactor

A new laser vaporization flow reactor (LVFR) is described consisting of a laser ablation cluster source combined with a fast flowtube reactor for the production and isolation of ligand-coated metal clusters. The source includes high repetition rate laser vaporization with a 100 Hz KrF (248 nm) excimer laser, while cluster growth and passivation with ligands takes place in a flowtube with ligand addition via a nebulizer spray. Samples are isolated in a low temperature trap and solutions containing the clusters are analyzed with laser desorption time-of-flight mass spectrometry. Initial experiments with this apparatus have trapped Ti _x (ethylenediamine) _y complexes which apparently have linear metal units with octahedral ligand coordination. Other experiments have produced and isolated clusters of the form Ti _x O _y (THF) _z that apparently have linear metal oxide cores and larger (TiO₂) _x (THF) _y nanoparticle species. The isolation of these new cluster species suggest that the LVFR instrument has considerable potential for the production of new nanocluster materials.     

激光剥蚀串联电感耦合等离子体质谱在环境分析中的应用进展

激光剥蚀串联电感耦合等离子体质谱法(LA-ICP-MS)是一种功能强大的化学元素检测方法,它具有样品前处理简单、多元素同时测定、高通量、高灵敏度、宽线性范围以及原位分析等优点.同时,激光剥蚀可以与多接收器电感耦合等离子体质谱仪(MC-ICP-MS)串联用于稳定同位素组成测定,不仅避免了繁琐的样品前处理,同时还可应用于固...     

Specific Decoration of a Discrete Bismuth Oxido Cluster by Selected Peptides towards the Design of Metal Tags

Metal tags find application in a multitude of biomedical systems and the combination with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) offers an opportunity for multiplexing. To lay the foundation for an increase of the signal intensities in such processes, we herein present a general approach for efficient functionalization of a well-defined metal oxido cluster [Bi₆O₄(OH)₄(SO₃CF₃)₆(CH₃CN)₆]⋅2 CH₃CN ( 1 ), which can be realized by selecting 7mer peptide sequences via combinatorial means from large one-bead one-compound peptide libraries. Selective cluster-binding peptide sequences ( CBS ) for 1 were discriminated from non-binders by treatment with H₂S gas to form the reduction product Bi₂S₃, clearly visible to the naked eye. Interactions were further confirmed by NMR experiments. Extension of a binding peptide with a maleimide linker ( Mal ) introduces the possibility to covalently attach thiol-bearing moieties such as biological probes and for their analysis the presence of the cluster instead of mononuclear entities should lead to an increase of signal intensities in LA-ICP-MS measurements. To prove this, CBS - Mal was covalently bound onto thiol-presenting glass substrates, which then captured 1 effectively, so that LA-ICP-MS measurements demonstrated drastic signal amplification compared to single lanthanide tags.     

激光解吸电离飞行时间质谱下的银簇行为

近年来,对金属簇的研究已成为化学与物理学中最活跃的研究领域之一［１］．金属簇被认为是介于单个原子与固体之间的中间相［２］．深入地研究其结构、形成机理及物理与化学行为,对于寻找新的催化剂［３］,重新认识气相化学与凝聚相化学的关系［４］,都有非常重要的意...     

纤维素金属螯合物及其质谱分析在研究血清蛋白质与多肽中的应用

用纤维素做固相支持物,通过碱处理、环氧活化、偶联螯合剂、固定金属离子等方法制成纤维素金属螯合物,并用合成的纤维素金属螯合物处理健康人血清,然后通过基质辅助激光解吸电离飞行时间质谱仪(MALDI-TOF-MS)检测蛋白质和多肽以确定其分离效果。确定了最佳的合成方法、螯合剂、金属离子和缓冲体系。再利用普通的纤维素制成了性能优良的纤维素金属螯合物,它能较好地分离血清中的蛋白质和多肽。     

应用基质辅助激光解吸质谱快速分析重组水蛭素产物的纯度与分子量

利用MALDI－TOF－MS测定了具有抗凝血活性的水蛭素基因重组产物（rHV-2)的纯度和分子量，实验测定结果与理论计算值一致，证明此基因重组产物的一级结构是正确，在表达，复性和纯化的过程中没有氨基酸的选择，变异和修饰。     

激光剥蚀-电感耦合等离子体质谱对高温合金中17种痕量元素的测定

建立了镍基高温合金中Sc、Cu、Zn、Ga、Ge、As、Ag、Cd、In、Sn、Sb、Te、Ce、Hf、Tl、Pb、Bi17种痕量元素的激光剥蚀-电感耦合等离子体质谱测定方法。对激光剥蚀进样及质谱分析条件进行了优化,通过激光对样品表面的层层剥蚀顺利完成了对低沸点杂质元素的测定。采用格栅扫描采样,严格控制样品的聚焦位置和散焦距离以保证采样的准确性,由高温合金系列标准物质建立了18种痕量元素的校正曲线,其中14种痕量元素的线性相关性较好(r2≥0.99),In、Sn、Sb、Ce、Tl、Pb、Bi等超痕量元素的检出限和气体空白分别低于或接近0.000 005%和0.000 001%。方法对镍基高温合金样品中Cu、Ga、Ag、Cd、In、Sn、Sb、Te、Hf、Tl、Pb和Bi等痕量元素的测定结果与参考值吻合较好,且大部分元素的RSD(n=4)小于或接近30%。     

Laser Desorption Ionization Versus Electrospray Ionization Mass Spectrometry: Applications in the Analysis of Cluster Anions

Mass spectra of transition metal carbonyl cluster anions were recorded using laser desorption ionization time-of-flight (LDI-TOF) and electrospray ionization (ESI) techniques. The LDI spectra generally contain peaks corresponding the intact cluster together with extensive CO loss fragments ions whereas the ESI spectra exhibit peaks corresponding the intact cluster together with few (if any) CO loss fragment ions. The parameters of both techniques can be modified to vary the extent of fragmentation. In all cases no fragmentation of the metal core is observed. Overall, ESI is a more informative method for the analysis of these types of cluster anions.     

钒氧阴离子团簇与小分子碳氢化合物反应的实验和理论研究(英文)

为了在分子层次上揭示相关催化反应的机理,人们对过渡金属氧化物团簇与碳氢化合物分子反应进行了大量研究.相比于过渡金属氧化物团簇阳离子,阴离子对一些碳氢化合物的活性弱得多,因此研究还很少.在本工作中,我们通过激光溅射产生钒氧团簇阴离子VxOy-,产生的团簇在接近热碰撞条件下与烷烃(C2H6和C4H10)以及烯烃(C2H4和C3H6)在一个快速流动反应管中进行反应,飞行时间质谱用来检测反应前后的团簇分布.在VxOy-与烷烃的反应中,生成了产物V2O6H-和V4O11H-;在与烯烃的反应中,产生了相应的吸附产物V4O11X-(X=C2H4或C3H6).密度泛函理论计算表明:V2O6-和V4O1-1可以活化烷烃(C2H6和C4H10)的C-H键,也可以与烯烃(C2H4和C3H6)发生3+2环化加成反应形成一个五元环结构(-V-O-C-C-O-),C-H键活化与环加成反应都需经历可以克服的反应能垒.理论计算与实验观测结果相符合.V2O6-和V4O1-1团簇都具有氧原子自由基(O·或O-)的成键特征,活性O-物种也经常出现在钒氧催化剂表面,因而本研究在分子水平上,揭示了表面活性氧物种与碳氢化合物反应的机理.