Multi-objective Optimal Design of High Frequency Probe for Scanning Ion Conductance Microscopy

Scanning ion conductance microscopy（SICM） is an emerging non-destructive surface topography characterization apparatus with nanoscale resolution. However, the low regulating frequency of probe in most existing modulated current based SICM systems increases the system noise, and has difficulty in imaging sample surface with steep height changes. In order to enable SICM to have the capability of imaging surfaces with steep height changes, a novel probe that can be used in the modulated current based bopping mode is designed. The design relies on two piezoelectric ceramics with different travels to separate position adjustment and probe frequency regulation in the Z direction. To fiarther improve the resonant frequency of the probe, the material and the key dimensions for each component of the probe are optimized based on the multi-objective optimization method and the finite element analysis. The optimal design has a resonant frequency of above 10 kHz. To validate the rationality of the designed probe, microstructured grating samples are imaged using the homebuilt modulated current based SICM system. The experimental results indicate that the designed high frequency probe can effectively reduce the spike noise by 26% in the average number of spike noise. The proposed design provides a feasible solution for improving the imaging quality of the existing SICM systems which normally use ordinary probes with relatively low regulating frequency.

Real-space observation on standing configurations of phenylacetylene on Cu(111) by scanning probe microscopy

The adsorption configurations of molecules adsorbed on substrates can significantly affect their physical and chemical properties. A standing configuration can be difficult to determine by traditional techniques, such as scanning tunneling microscopy(STM) due to the superposition of electronic states. In this paper, we report the real-space observation of the standing adsorption configuration of phenylacetylene on Cu(111) by non-contact atomic force microscopy(nc-AFM).Deposition of phenylacetylene at 25 K shows featureless bright spots in STM images. Using nc-AFM, the line features representing the C–H and C–C bonds in benzene rings are evident, which implies a standing adsorption configuration. Further density functional theory(DFT) calculations reveal multiple optimized adsorption configurations with phenylacetylene breaking its acetylenic bond and forming C–Cu bond(s) with the underlying copper atoms, and hence stand on the substrate.By comparing the nc-AFM simulations with the experimental observation, we identify the standing adsorption configuration of phenylacetylene on Cu(111). Our work demonstrates an application of combining nc-AFM measurements and DFT calculations to the study of standing molecules on substrates, which enriches our knowledge of the adsorption behaviors of small molecules on solid surfaces at low temperatures.

Combination of Instrumented Nanoindentation and Scanning Probe Microscopy for Adequate Mechanical Surface Testing

The elastic indentation modulus and hardness of standard bulk materials and advanced thin films were determined by using the nanoindentation technique followed by the Oliver- Pharr post-treatment. After measurements with different loading/unloading schemes on chemically polished bulk titanium a substantial decrease of both modulus and hardness vs an increasing loading time was found. Then, hard nanostructured TiBN and TiCrBN thin films deposited by magnetron sputtering （using multiphase targets） on substrates of high roughness （sintered hard metal） and low roughness （silicon） were studied. Experimental modulus and hardness characterized by using two different nanoindenter tools were within the limits of standard deviation. However, a strong effect of roughness on the spread of the experimental values was observed and it was found that hardness and elastic indentation modulus obeyed a Gaussian distribution. The experimental data were discussed together with scanning probe microscopy （SPM） images of typical imprints taken after the nanoindentation tests and the local topographyls strong correlation with the results of nanoindentation was described.

Correlating the Interfacial Polar-Phase Structure to the Local Chemistry in Ferroelectric Polymer Nanocomposites by Combined Scanning Probe Microscopy

Ferroelectric polymer nanocomposites possess exceptional electric properties with respect to the two otherwise uniform phases,which is commonly attributed to the critical role of the matrix-particle interfacial region.However,the structure-property correlation of the interface remains unestablished,and thus,the design of ferroelectric polymer nanocompos-ite has largely relied on the trial-and-error method.Here,a strategy that combines multi-mode scanning probe microscopy-based electrical charac-terization and nano-infrared spectroscopy is developed to unveil the local structure-property correlation of the interface in ferroelectric polymer nano-composites.The results show that the type of surface modifiers decorated on the nanoparticles can significantly influence the local polar-phase content and the piezoelectric effect of the polymer matrix surrounding the nano-particles.The strongly coupled polar-phase content and piezoelectric effect measured directly in the interfacial region as well as the computed bonding energy suggest that the property enhancement originates from the formation of hydrogen bond between the surface modifiers and the ferroelectric polymer.It is also directly detected that the local domain size of the ferroelectric polymer can impact the energy level and distribution of charge traps in the interfacial region and eventually influence the local dielectric strength.

Influence of the probe-sample interaction on scanning near-field optical microscopic images in the far field

We have studied the influence of probe-sample interaction in a scanning near-field optical microscopy （SNOM） in the far field by using samples with a step structure. For a sample with a step height of - λ/4, the SNOM image contrast between the two sides of the step changes periodically at different scan heights. For a step height of-λ/2, the image contrast remains approximately the same. The probe-sample interaction determines the SNOM image contrast here. The influence of different refractive indices of the sample has been also analysed by using a simple theoretical model.

Surface Properties of Cement Paste Evaluated by Scanning Probe Microscopy

The microscopic physical properties of Hardened Cement Paste (HCP) surfaces were evaluated by using Scanning Probe Microscopy (SPM). The cement pastes were cured under a hydrostatic pressure of 400 MPa and the contacting surfaces with a slide glass during the curing were studied. Scanning Electron Microscope (SEM) observation at a magnification of 7000 revealed smooth surfaces with no holes. The surface roughness calculated from the SPM measurement was 4 nm. The surface potential and the frictional force measured by SPM were uniform throughout the measured area 24 h after the curing. However, spots of low surface potential and stains of low frictional force and low viscoelasticity were observed one month after curing. This change was attributed to the carbonation of hydrates.

A First Principles Simulation Framework for the Interactions between a Si(001) Surface and a Scanning Probe

By means of total energy calculations within the framework of the local density approximation (LDA), the interactions between a silicon Si(001) surface and a scanning probe are investigated. The tip of the probe, comprising 4 Si atoms scans along the dimer lines above an asymmetric p(2 × 1) surface, at a distance where the chemical interaction between tip-surface is dominant and responsible for image resolution. At that distance, the tip causes the dimer to toggle when it scans above the lower atom of a dimer. The toggled dimers create an alternating pattern, where the immediately adjacent neighbours of a toggled dimer remain unchanged. After the tip has fully scanned across the p(2 × 1) surface, causes the dimers to arrange in a p(2 × 2) reconstruction, reproducing the images obtained in scanning probe experiments. Our modelling methodology includes simulations that reveal the energy input required to overcome the barrier to the onset of dimer toggling. The results show that the energy input to overcome this barrier is lower for the p(2 × 1) surface than that for the p(2 × 2) or c(4 × 2) surfaces.

Accelerating the Feedback Loop in Scanning Probe Microscopes without Loss of Height Measurement Accuracy by Using Pixel Forecast Methods

Scanning probe microscopes (SPM) are limited in their speed of data acquisition by the mechanical stability of the scanner. Therefore many types of scanners have been developed to achieve a rigid setup while maintaining an acceptable image size. We have followed here a different path to accelerate data acquisition by improving the feedback loop to achieve the same SPM image quality in a shorter time. While the feedback loop in a scanning probe microscope typically starts to probe a new pixel starting from the previous position, we have reduced the total control time by using an improved starting point for the feedback loop at each pixel. By exploiting the information of the already scanned pixels a forecast for the new pixel is created. We have successfully used several simple methods for a prognosis in MATLAB simulations like one dimensional linear or cubic extrapolation and others. Only scanning tunnelling microscope data from real experiments were used to test the forecasts. A doubling of the speed was achieved in the most favourable cases.

Electrochemical scanning probe microscopies for artificial photosynthesis

The rational design of efficient artificial photosynthetic components requires thorough understandings towards(photo)electrochemical properties and kinetic processes at the solid/liquid interface.Electrochemical scanning probe microscopy(EC-SPM),which enables the high-spatial resolution imaging in an electrolyte environment,becomes an indispensable experimental technique for operando studies of(photo)electrochemistry.This review summarizes the latest results of relevant ECSPM techniques to study the interfacial properties of electrocatalysts and photoelectrodes.Covered methods include atomic force microscopy,Kelvin probe force microscopy,conductive atomic force microscopy,scanning tunneling microscopy,scanning electrochemical microscopy,and other advanced SPM-based operando techniques.Finally,we offer some perspectives on the future outlook in this fascinating research area.

Graphene and 2D TMD material optical characterization with scanning probe microscopy

Two-dimensional(2D)materials distinguish themselves by high specific surface areas and wide tunability in nanophotonics research.As the developing of 2D materials optical and opto-electronic investigations,scanning probe microscopy provides high spatial resolution and strong local field confinement,which can realize the single molecular and atomic level of characterization.Here,we review the nanophotonic and opto-electronic features of both pristine and hybrid 2Dmaterials which are measured by scanning probe microscopy.The conclusion and prospective of scanning probe techniques for the future2Dmaterials characterization and practical applications are presented.

A Comprehensive FIB Lift-out Sample Preparation Method for Scanning Probe Microscopy

In this work,we investigate cross-sectional sample preparation for atomic force microscopy and general scanning probe microscopy(SPM)characterization.In light of traditional cross-sectional sample preparation solutions for transmission electron microscopy,mechanical polishing and focused ion beam(FIB)milling have been employed to prepare cross-sectional samples for SPM.We present an optimized solution for thin films and oxide heterostructures that allows for examining the prepared surfaces using various SPM techniques.In particular,post-cleaning after FIB milling is shown to be crucial and precision ion polishing was conducted to remove rough layers on mechanically polished samples.We also study SPM mechanical milling to remove amorphous layers on FIB-milled samples.Consequently,a reliable solution for making cross sections suitable for SPM has been achieved providing a useful methodology that can also be employed for other material systems with different hardness,such as polymers and metals.

Scanning probe microscopy in probing low-dimensional carbon-based nanostructures and nanomaterials

Carbon,as an indispensable chemical element on Earth,has diverse covalent bonding ability,which enables construction of extensive pivotal carbon-based structures in multiple scientific fields.The extraordinary physicochemical properties presented by pioneering synthetic carbon allotropes,typically including fullerenes,carbon nanotubes,and graphene,have stimulated broad interest in fabrication of carbon-based nanostructures and nanomaterials.Accurate regulation of topology,size,and shape,as well as controllably embedding target sp^(n)-hybridized carbons in molecular skeletons,is significant for tailoring their structures and consequent properties and requires atomic precision in their preparation.Scanning probe microscopy(SPM),combined with on-surface synthesis strategy,has demonstrated its capabilities in fabrication of various carbon-based nanostructures and nanomaterials with atomic precision,which has long been elusive for conventional solution-phase synthesis due to realistic obstacles in solubility,isolation,purification,etc.More intriguingly,atom manipulation via an SPM tip allows unique access to local production of highly reactive carbon-based nanostructures.In addition,SPM provides topographic information of carbon-based nanostructures as well as their characteristic electronic structures with unprecedented submolecular resolution in real space.In this review,we overview recent exciting progress in the delicate application of SPM in probing low-dimensional carbon-based nanostructures and nanomaterials,which will open an avenue for the exploration and development of elusive and undiscovered carbon-based nanomaterials.

扫描探针显微术SPM标准化现状研究

本文结合扫描探针显微术(Scanning Probe Microscopy,SPM)的专业性与多样性和标准化工作的要求,初步构建了符合领域发展的三维架构的SPM标准体系。接着,研究了SPM通用基础、关键部件/产品与应用检测方面的相关国家标准技术内容,说明当前SPM标准化与标准体系的建设情况。最后,在当前技术与产业状态下,提出以实现量值统一、接口兼容、质量可评价、结果可比较为目标,宜重点开展SPM性能指标检验标准、SPM成像质量的调整与评价方法标准、共性的SPM应用标准或指南标准等三方面的工作,完善我国SPM标准体系。

含Benzo[a]azulene单元的锯齿状梯形共轭聚合物的表面在位合成

梯形共轭聚合物(CLPs)因其独特的光电性质而受到广泛关注。绝大多数CLPs是通过溶液方法合成的,但近年来,在超高真空环境中进行的表面原位合成策略逐渐崭露头角,成为CPL合成的新方法。表面原位合成方法能够克服传统溶液合成的限制,如随着聚合度增加而受限的溶解度和结构稳定性,从而实现复杂共轭结构的精确合成。Azulene衍生物是在表面合成非苯型CLPs的有吸引力的前体。与传统的只含六元环的CLPs相比,使用烷基取代的azulene作为前体分子,有望获得具有复杂骨架结构的CLPs,从而调控其电子性质,但目前很少有人探索这种策略。本文报道了3,3'-二溴-2,2’-二甲基-1,1’-联薁(DBMA)在Au(111)表面上的热化学反应。在室温的Au(111)衬底上,我们发现沉积的分子在重构表面的fcc(面心立方堆积)区域形成无定型的聚集体,并在100℃以下保持形貌不变。当退火温度高于150℃后,DBMA发生脱溴反应并与金原子络合形成具有复杂空间立体结构的2,2’-二甲基-1,1’-联薁有机金属聚合物,并展现出迥异的图像特征。随后在更高温度下退火,有机金属聚合物脱去金属原子并经历碳碳偶联反应。该过程伴随着甲基与相邻薁单元之间的分子内环化反应,形成了含有benzo[a]azulene单元的梯形共轭聚合物。有趣的是,我们发现当一侧甲基参与反应并在聚合物中形成六元环时,会显著地弯折聚合物链,使得另一侧甲基与薁单元之间的距离增加,并抑制预期的环化过程。我们通过键分辨扫描探针显微镜对反应过程中的相关结构进行了研究,发现反应结果与反应中间结构的应力关联紧密。我们的结果表明,烷基取代的azulene前体可应用于非苯型碳纳米结构的表面合成,并有望实现扩展的非苯型二维碳纳米结构。

AlSc15中间合金中Al_(3)Sc金属间化合物的电化学行为及对局部腐蚀的影响

将过共晶AlSc15合金加热至液态,以10℃/h速率冷却得到毫米级尺寸的Al_(3)Sc金属间化合物。利用微区电化学和扫描开尔文探针力显微镜(SKPFM)研究了Al_(3)Sc金属间化合物在不同pH值的0.1 mol/L NaCl溶液中的电化学特征及对局部腐蚀敏感性的影响。结果表明,Al_(3)Sc金属间化合物存在自钝化现象,且在碱性环境中有明显的维钝区域;随着pH值的增加,Al_(3)Sc腐蚀电位逐渐降低,在中性和碱性条件下的腐蚀速率明显低于酸性条件下的;Al_(3)Sc金属间化合物与周围铝基体之间的伏打电位差约为40 mV,在铝合金中可能作为较弱的局部阴极,对电偶腐蚀的影响不大。

基于干式制冷的低温扫描探针显微镜研究进展

21世纪以来,扫描探针显微镜(scanning probe microscope,SPM)在微纳尺度形貌表征、物性测量及微纳加工等领域发挥着越来越重要的作用.为了使扫描探针显微镜获得更稳定的运行环境、更高的能量分辨率,人们研发了具备超高真空(ultra high vacuum,UHV)和低温(low temperature,LT)环境的SPM系统(UHV-LT-SPM).目前,大多数的UHV-LT-SPM系统通过向连续流式低温恒温器或低温杜瓦中输送液态氦-4(4He),使SPM的温度达到约4.2 K.然而由于4He元素在自然界中含量低且因需求日益增长,导致液氦价格急剧飙升,严重影响到了4He相关低温设备的正常运行.为应对上述问题,干式制冷技术成为新一代低温技术的发展方向.在此背景下,将干式制冷技术与扫描探针显微镜相结合,搭建干式低温扫描探针显微镜,成为了目前扫描探针仪器领域的研究重点之一.本文主要从扫描探针显微镜系统设计、降温设计、减振方法以及其设备性能等方面,介绍目前已经报道的几种干式LT-SPM系统.最后总结了干式LT-SPM系统目前所遇见的问题和挑战,探讨了该技术未来的发展方向.

A review on the synergism between corrosion and fatigue of magnesium alloys:Mechanisms and processes on the micro-scale

Understanding the interaction between cyclic stresses and corrosion of magnesium(Mg)and its alloys is increasingly in demand due to the continuous expansion of structural applications of these materials.This review is dedicated to exploring the corrosion-fatigue mechanisms of these materials,with an emphasis on microscale processes,and the possibility of expanding current knowledge on this topic using scanning electrochemical techniques.The interaction between fatigue and corrosion of Mg alloys is analyzed by considering the microstructural aspects(grain size,precipitates,deformation twins),as well as the formation of pits.Furthermore,in the case of coated alloys,the role of coating defects in these phenomena is also described.In this context,the feasibility of using scanning electrochemical microscopy(SECM),scanning vibrating electrode technique(SVET),scanning ion-selective electrode technique(SIET),localized electrochemical impedance spectroscopy(LEIS)and scanning Kelvin probe(SKP)methods to study the corrosion-fatigue interaction of Mg alloys is examined.A comprehensive review of the current literature in this field is presented,and the opportunities and limitations of consolidating the use of these techniques to study the microscale processes involved in Mg corrosion-fatigue are discussed.

Micro-galvanic corrosion behaviour of Mg-(7,9)Al-1Fe-xNd alloys

The localized micro-galvanic corrosion process and the kinetic information of Mg-(7,9)Al-1Fe-x Nd alloys were investigated by in situ observation under electrochemical control and in situ atomic force microscopy(AFM)in an electrolyte environment.The results revealed that the formation of the Nd-rich phase in alloys resulted in a decrease in the Volta potential difference from~400 m V(AlFe3/α-Mg)to~220 mV(Nd-rich/α-Mg),reducing the corrosion products around the cathodic phase and corrosion current density of the microscale area.The addition of Nd significantly improved the corrosion resistance,mainly due to the suppression of the micro-galvanic corrosion between the second phases and substrate.Finally,the corrosion mechanism of Mg-(7,9)Al-1Fe-x Nd alloys was discussed based on in situ observations and electrochemical results.

On-Surface Stereochemical Characterization of a Highly Curved Chiral Nanographene by Noncontact Atomic Force Microscopy and Scanning Tunneling Microscopy

A highly distorted chiral nanographene structure composed of triple corannulene-fused[5]helicenes is prepared with the help of the Heck reaction and oxidative photocyclization with an overall isolated yield of 28%.The complex three-dimensional(3D)structure of the bowl-helix hybrid nanostructure is studied by a combination of noncontact atomic force microscopy(AFM)and scanning tunneling microscopy(STM)on the Cu(111)surface,density functional theory calculations,AFM/STM simulations,and high-performance liquid chromatography-electronic circular dichroism analysis.This examination reveals a molecular structure in which the three bowl-shaped corannulene bladesd position themselves in a C3-symmetric fashion around a highly twisted triphenylene core.The molecule appears to be shaped like a propeller in which the concave side of the bowls face away from the connected[5]helicene motif.The chirality of the nanostructure is confirmed by the direct visualization of both MMM and PPP enantiomers at the single-molecule level by scanning probe microscopies.These results underline that submolecular resolution imaging by AFM/STM is a powerful real-space tool for the stereochemical characterization of 3D curved chiral nanographene structures.

扫描探针显微技术线上线下混合式教学探索

扫描探针显微技术是一门讲授扫描探针显微镜理论知识和实践操作的课程。该课程通过理论教学,促使学生扎实掌握不同类型扫描探针显微镜的基本构造和原理;通过实践教学,使学生加深对扫描探针显微镜功能的理解,培养学生的动手能力和思维能力。在国家提倡线上线下混合式教学的背景下,以扫描探针显微技术课程为例,探索开展线上线下混合式教学的路径,以期为相关课程的教学改革提供借鉴。