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Surface bonding on silicon surfaces as probed by tip-enhanced Raman spectroscopy

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Science China Chemistry 2010年第2期53卷 426-431页

作者： ZHUANG MuDe LIU Zheng REN Bin tian zhongqun State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China

Tip-enhanced Raman spectroscopy (TERS) has been used to obtain the Raman signal of surface species on silicon single crystal surfaces without the necessity for surface enhancement by addition of Ag nanoparticles. By illuminating the hydrogen terminated silicon surface covered with a droplet of 4-vinylpyridine with UV light, a 4-ethylpyridine modified silicon surface can be easily obtained. By bringing a scanning tunneling microscope (STM) Au tip with a nanoscale tip apex to a distance of ca. 1 nm from the modified silicon surface, enhanced Raman signals of the silicon phonon vibrations and the surface-bonded 4-ethylpyridine were obtained. The Raman enhancement factor was estimated to be close to 107. By comparing the surface enhanced Raman scattering (SERS) signal obtained after surface enhancement with Ag nanoparticles and the TERS signal of the surface, the advantage of TERS over SERS for characterizing the surface species on substrates becomes apparent: TERS readily affords vibrational information about the system without disturbing it by surface enhancement. In this sense, TERS can be considered a truly non-invasive tool which is ideal for characterizing the actual surface species on substrates.

关键词： tip-enhanced Raman spectroscopy silicon single crystal 4-ethylpyridine surface modification

Micro/nanoelectrode-based electrochemical methodology for single cell and organelle analysis

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Nano Research 2024年第1期17卷 196-206页

作者： Chuchu Xu De Yang Yuchan Wang Ruolin Liu Fan Wang zhongqun tian Keke Hu Department of Chemistry College of Chemistry&Chemical EngineeringXiamen UniversityXiamen 361005China

Cells are the basic unit of *** analysis of single cells/organelles is essential for uncovering the molecular mechanisms of physiological and pathological processes that are difficult to elucidate on a larger *** paper provides an overview of the commonly used fabrication methods for micro/nanoelectrodes applied in the investigations of single cells/organelles as well as the corresponding electrochemical measurements over the last four years including extracellular measurement,combination of extra and intracellular measurement,intracellular reactive oxygen species and reactive nitrogen species(ROS/RNS)measurement,and isolated organelles measurement.

关键词： single cell/organelle micro/nanoelectrode electrochemical measurement chemical transmitters

Au＋-cetyltrimethylammonium bromide solution： A novel precursor for seed-mediated growth of gold nanoparticles in aqueous solution

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Nano Research 2013年第1期6卷 29-37页

作者： Chaoyu Li Fengru Fan Bingsheng Yin Liang Chen Tapan Ganguly zhongqun tian State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China Department of Physics Bengal Engineering and Science University Shibpur Howrah 711103 India

The appropriate choice of chemical composition of a metallic precursor, which produces the basic structure units in the growth process of nanocrystals, is a high priority in the synthesis of metal--especially Au--nanoparticles. In the present work, Au seeds （prepared by the reduction of Au3＋ solution with NaBI~ in the presence of cetyltrimethylammonium bromide （CTAB）） have been used to initiate the growth of Au nanoparticles from two different Au precursors. When an aqueous Au＋ solution prepared in the presence of CTAB micelles was treated with ascorbic acid in the presence of the gold seeds, a high yield （up to 92%） of gold nanoparticles was obtained. By varying the volume of the seed solution with a fixed amount of Au＋, we can effectively control the morphological transformation of the resulting Au nanoparticles from cubes to octahedra. When an aqueous Au3＋ solution was prepared in the presence of CTAB micelles and treated with ascorbic acid in the presence of the gold seeds, smaller yields of Au nanoparticles were obtained. A preliminary growth mechanism has been proposed based on the changes induced by varying the amount of ascorbic acid and the ratio of the concentration of Au＊ to the number of seeds.

关键词： Au+ cetyltrimethylam monium bromide (CTAB) solution precursor seed mediated growth gold nanoparticles

Unexpected current-voltage characteristics of mechanically modulated atomic contacts with the presence of molecular junctions in an electrochemically assisted-MCBJ

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Nano Research 2016年第2期9卷 560-570页

作者： Yang Yang Junyang Liu Shi Feng Huimin Wen Jinghua tian Jueting Zheng Bernd Schollhorn Christian Amatore Zhongning Chen zhongqun tian Department of Chemistry/Pen-Tung Sah Institute of Micro-Nano Science and Technology State Key Laboratory of Physical Chemistry of Solid Surfaces and LIA CNRS NanoBioCatEchem Collaborative Innovation Center of Chemistry for Energy Materials Xiamen University Xiamen 361005 China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of SciencesFuzhou 350002 China CNRS UMR 8640 PASTEUR and LIA CNRS NanoBioCatEchem Ecole Normale Superieure-PSL Research University Departement de Chimie Sorbonne Universit~s - UPMC Paris 6 24 rue Lhomond 75005 Paris France

In this article, we report on the characterization of various molecular junctions＇ current-voltage characteristics （Ⅰ-Ⅴ curves） evolution under mechanical modulations, by employing a novel electrochemically assisted-mechanically controllable break junction （EC-MCBJ） method. For 1,4-benzenedithiol, the Ⅰ-Ⅴ curves measured at constant electrode pair separation show excellent reproducibility, indicating the feasibility of our EC-MCBJ method for fabricating molecular junctions. For ferrocene-bisvinylphenylmethyl dithiol （Fc-VPM）, an anomalous type of Ⅰ-Ⅴ curve was observed by the particular control over the stepping motor. This phenomenon is rationalized assuming a model of atomic contact evolution with the presence of molecular junctions. To test this hypothesized model, a molecule with a longer length, 1,3-butadiyne-linked dinuclear ruthenium（H） complex （Ru-1）, was implemented, and the Ⅰ-Ⅴ curve evolution was investigated under similar circumstances. Compared with Fc-VPM, the observed Ⅰ-Ⅴ curves show close analogy and minor differences, and both of them fit the hypothesized model well.

关键词： molecular junction electrochemical deposition mechanically controllable break junction (MCBJ) ruthenium complex ferrocenyl molecular wire

An Electrochemically Assisted Mechanically Controllable Break Junction Approach for Single Molecule Junction Conductance Measurements

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Nano Research 2011年第12期4卷 1199-1207页

作者： Yang Yang Zhaobin Chen Junyang Liu Miao Lu Dezhi Yang Fangzu Yang zhongqun tian State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China Micro-Electro-Mechanical Systems Research Center Pen-Tung Sah Micro-Nano Technology Institute Xiamen University Xiamen 361005 China

We report an electrochemically assisted mechanically controllable break junction （EC-MCBJ） approach to investigating single molecule conductance. Electrode pairs connected with a gold nanobridge were fabricated by electrochemical deposition and then mounted on a homebuilt MCBJ platform. A large number of Au- molecule-Au junctions were produced sequentially by repeated breaking and reconnecting of the gold nanobridge. In order to measure their single molecule conductance, statistical conductance histograms were generated for benzene-l,4-dithiol （BDT） and 4,4＇-bipyridine （BPY）. The values extracted from these histograms were found to be in the same range as values previously reported in the literature. Our method is distinct from the ones used to acquire these previously reported literature values, however, in that it is faster, simpler, more cost-effective, and changing the electrode material is more convenient.

关键词： Single molecule junction conductance electrochemical deposition mechanically controlled break junction (MCBJ) benzene-l 4-dithiol bipyridine

Ultrahigh-performance mesoporous ZnMn2O4 microspheres as anode materials for lithium-ion batteries and their in situ Raman investigation

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Nano Research 2018年第7期11卷 3814-3823页

作者： Xiaobin Zhong1 Xiaoxiao wang Huiyuan Wang Zhizheng Yang Yuxiong Jiang Jianfeng Li zhongqun tian MOE Key Laboratory of Spectrochemical Analysis and Instrumentation State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Xiamen University Xiamen 361005 China Key Laboratory of Automobile Materials Ministry of Education College of Materials Science and Engineering Jilin University Changchun 130012 China

Currently, lithium-ion batteries play a key role in energy storage; however, their applications are limited by their low energy density. Here, we design a facile method to prepare mesoporous ZnMn2O4 microspheres with ultrahigh rate performance and ultralong cycling properties by finely tuning the solution viscosity during synthesis. When the current density is raised to 2 A·g^-1, the discharge capacity is maintained at 879 mA·h·g^-1 after 500 cycles. The electro- chemical properties of mesoporous ZnMn2O4 microspheres are better than that for most reported ZnMn2O4. To understand the electrochemical processes on the mesoporous ZnMn2O4 microspheres, in situ Raman spectroscopy is used to investigate the electrode surface. The results show that mesoporous ZnMn2O4 microspheres have a great potential as an alternative to commercial carbon anode materials.

关键词： ZnMn2O4 mesoporous microspheres viscosity in situ Raman ultralong cycling stability

Promising electroplating solution for facile fabrication of Cu quantum point contacts

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Nano Research 2017年第10期10卷 3314-3323页

作者： Yang Yang Junyang Liu Jueting Zheng Miao Lu Jia Shi Wenjing Hong Fangzu Yang zhongqun tian State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Pen-Tung Sah Institute ot Micro-Nano Science and Technology LIA CNRS NanoBioCatEchem Collaborative Innovation Center of Chemistry for Energy Materials Xiamen University Kiamen 361005 China

In this article, we report on the fabrication and transport measurements of Cu quantum point contacts prepared by a novel, electrochemically assisted mechanically controllable break junction （EC-MCBJ） method. By employing photolithography and wet-etching processes, suspended electrode pairs were patterned and fabricated successfully on Si microchips. Rather than adopting an acid Cu electroplating solution, a novel alkaline electroplating solution was developed and utilized to establish Cu nanocontacts between electrode pairs. Typically, the widths of the as-fabricated Cu nanocontacts were found to be smaller than 18 nm. A large number of Cu quantum point contacts were then produced and characterized by a home-built MCBJ setup. In addition to the conventional histogram, where peaks tend to decrease in amplitude with increasing conductance, an anomalous type of conductance histogram, exhibiting different peak amplitudes, was observed. Through statistical analysis of the maximum allowable bending of the Si microchips, and theoretical calculations, we demonstrated that our alkaline Cu electroplating solution affords Cu nanocontacts that are compatible with subsequent MCBJ operations, which is essential for the fabrication of Cu quantum point contacts. As sophisticated e-beam lithography is not required, the EC-MCBJ method is fast, simple, and cost-effective. Moreover, it is likely to be suitable for the fabrication and characterization of quantum point contacts of various metals from their respective electroplating solutions.

关键词： quantum point contact electrochemical deposition Cu nanowire mechanically controllablebreak junction (MCBJ) conductance quantization

FDTD for plasmonics:Applications in enhanced Raman spectroscopy

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Chinese Science Bulletin 2010年第24期55卷 2635-2642页

作者： YANG ZhiLin LI QianHong RUAN FangXiong LI ZhiPeng REN Bin XU HongXing tian zhongqun Department of Physics Xiamen University Xiamen 361005 China Institute of Physics Chinese Academy of Sciences Beijing 100190 China Department of Chemistry Xiamen University Xiamen 361005 China

The exact electromagnetic enhancement mechanism behind SERS,TERS,HERS and SHINERS is one of the issues focused on in the study of enhanced Raman *** three dimensional finite difference time domain method(3D-FDTD),which is widely used in nanoplasmonic simulations,not only provides us with a powerful numerical tool for theoretical studies of the ERS electromagnetic enhancement mechanism,but also serves as a useful tool for the design of ERS-active systems with higher sensitivities and spectral spatial *** this paper,we first introduce the fundamental principles of FDTD algorithms,and then the size-dependent dielectric function of dispersive metallic material is discussed.A comparative study of FDTD and rigorous Mie evaluations of electromagnetic fields in the vicinity of a system of self-similar nanospheres shows an excellent correlation between the two computational methods,directly confirming the validity and accuracy of 3D-FDTD simulations in ERS ***,we demonstrate,using a TERS calculation as an example,that the non-uniform mesh method can be more computationally efficient without loss of accuracy if it is applied correctly.

关键词：增强拉曼光谱 FDTD法应用时域有限差分法时域有限差分算法电磁增强机理 SERS效应有限差分模拟

Probing the kinetics in supramolecular chemistry and molecular assembly by microfluidic-NMR spectroscopy

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Science China Chemistry 2018年第11期61卷 1460-1464页

作者： Hongxun Fang Yibin Sun Xinchang Wang Manvendra Sharma Zhong Chen Xiaoyu Cao Marcel Utz zhongqun tian State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Collaborative Innovation Center of Chemistry for Energy Materials and Key Laboratory of Chemical Biology of Fujian Province Xiamen University Department of Electronic Science Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance Xiamen University School of Chemistry University of Southampton

Microfluidic-NMR spectroscopy has been extended to study the kinetics in supramolecular chemistry and molecular *** of a multicomponent host-guest supramolecular system containing viologen derivatives, β-cyclodextrins and cucurbit[7]urils are studied by a PMMA based microfluidic chip combined with a dedicated transmission line probe for NMR *** combining microfluidic technology with NMR spectroscopy, the amount of material required for a full kinetic study could be minimized. This is crucial in supramolecular chemistry, which often involves highly sophisticated and synthetically costly building blocks. The small size of the microfluidic structure is crucial in bringing the time scale for kinetic monitoring down to seconds. At the same time, the transmission line NMR probe provides sufficient sensitivity to work at low(2 m M) concentrations.

关键词： microfluidic-NMR molecular assembly host-guest chemistry kinetics