摘要:

We report about the development of a multifunctional AFM probe, which allows to perform simultaneous measurements of topography and electrical properties of biological samples in a buffer solution. The quality of the AFM probes has been experimentally assessed by acquiring topography measurements of bacteriorhodopsin membranes in buffer solution and topographical and electrical current images of HOPG in air. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639691

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Both the processes of adsorption of double‐stranded DNA and its desorption from the surface of freshly cleaved mica can be studied thanks to the Scanning Force Microscope (SFM). The adsorption can be investigated under different conditions with methods ranging from the simple count of adsorbed DNA molecules to the more elaborate study of the local curvature of the adsorbed DNA chains: this high‐resolution information is shedding light on the process of structure‐dependent DNA adsorption on crystal surfaces. SFM‐based Single‐Molecule Force Spectroscopy is very useful for studying the desorption process of DNA from the same surfaces, with the same level of environmental control. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639692

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We developed a control circuitry for non‐contact atomic force microscopy which generates a self‐excited vibration in a cantilever with a frequency up to 100 MHz, and detects its frequency modulation by a novel frequency demodulation technique. The circuitry was tested by applying it to an AFM whose tip vibration was parallel to sample surface. While the self‐excitation loop has only a simple superheterodyne configuration, the excited vibration was as stable as we could obtain a topographic image of Si (111)‐(7×7) surface with frequency feedback. The frequency demodulator is based on IQ (in‐phase and quadrature‐phase) direct frequency conversion to zero Hz intermediate frequency and operations including differentiations, multiplications and a subtraction between these signals. It was implemented as an analog circuit. We obtained an atomic step image in graphite by using this demodulator in frequency regulation feedback. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639693

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A magnetic force microscope has been constructed to image fluxlines in superconductors. In order to facilitate operation at low temperatures, cantilever deflections are detected with an interferometer which requires only an optical fibre in the cryostat. The design and modes of operation of the microscope are described. Room temperature AFM and MFM images are presented. The MFM results, combined with planned experimental improvements, point towards future success in imaging fluxlines. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639694

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

An Atomic Force Microscope (AFM) designed specially for operating under ultrahigh vacuum (UHV) and at low temperature is described. The normal and lateral forces acting between the tip and the sample can be measured simultaneously through the deflection of an optical beam onto a split detector. The laser beam is coupled into a single‐mode optical fiber and is focused by an aspheric lens onto the cantilever. Two identical spherical inertial sliders allow adjusting the position of the beam on the cantilever and on the photodiode respectively. The microscope is very rigid, compact and symmetric in order to minimize any thermal drifts and mechanical vibrations. Tips and samples are easily exchangeable under UHV conditions. The scanner position can be adjusted on a two‐dimensions plane in order to approach the sample towards the tip and/or to move laterally the sample. Three four‐quadrants piezotubes, forming an inertial slider, are driven by a slow‐charging and fast‐discharging high‐voltage capacitor signal. The AFM body is made of copper and fit inside a UHV‐compatible cryostat for operating at low temperature. The microscope can operate in contact mode and in intermediate contact mode. Results obtained on DNA plasmids are presented. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639695

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Apertureless magneto‐optical near‐field microscopy is developed for studying sub‐picosecond spindynamics at nanometer spatial scale. Polarization modulation and tip vibrations are implemented. Polarization responsivity of the tip‐induced scattering is demonstrated using polarization modulation and tip vibrations. A near‐field magneto‐optical contrast is achieved for a thin ferromagnetic film with in‐plane magnetization; however, its interpretation is shown to be nontrivial. Distribution of the evanescent field is measured vs. tip‐sample distance. Interference of the near‐field with the far‐field scattered light is found at distances ca. 300 nm and more, and strong tip‐surface interaction that quenches the detected scattering is found at distances below 20 nm. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639696

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The detection and analysis of molecular layers on surfaces can be based on a measurement of the dispersion relation of surface plasmons. In order to reduce the amount of adsorbed molecules needed they should be locally concentrated. This requires the knowledge of the behavior of plasmons for lateral variations in the dielectric part of the interface. A SNOM set‐up is presented to study plasmon propagation. A model study for a structured PMMA layer on a silver surface gives insight into the typical plasmon behavior. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639697

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Because of the limitation of the budget for laboratory courses, it is difficult to provide modern equipment for young students. In this work we show how students can build a state‐of‐the‐art UHV STM system on their own, with only a small budget and within a limited time period of three months. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639698

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

A description of the instrumental requirements for AFM‐based nanomanipulation system is presented, as well as the design, the features and the benefits of our force feedback nano‐scale manipulator. The description covers as well some software aspects for quick and successful nano‐manipulation. As an illustration, cross sectioning of carbon nanotube (CNT) and WS2nanotubes are shown. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639699

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present a self‐actuating and self‐sensing probe, with an electrically connected, monolithic tip for dynamic AFM. It is based on a quartz tuning fork and a microfabricated cantilever. The tuning fork — cantilever assembly opens a new avenue for electrically contacting the tip in a reproducible way. Such a probe can be used for scanned gate microscopy and for atomic force probers. Since the probe is self‐sensing, the probe can be used in environments where optical readout is not possible. Our probes allows for batch fabrication and assembly. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1639700

出版商:AIP    

年代:1903

数据来源: AIP