scholarly journals Length-extension resonator as a force sensor for high-resolution frequency-modulation atomic force microscopy in air

2016 ◽  
Vol 7 ◽  
pp. 432-438 ◽  
Author(s):  
Hannes Beyer ◽  
Tino Wagner ◽  
Andreas Stemmer
Keyword(s):  
Atomic Force Microscopy ◽  
High Resolution ◽  
Frequency Modulation ◽  
High Vacuum ◽  
Force Sensor ◽  
Ultra High Vacuum ◽  
Dew Point ◽  
Ambient Conditions ◽  
Force Microscopy ◽  
Atomic Force

Frequency-modulation atomic force microscopy has turned into a well-established method to obtain atomic resolution on flat surfaces, but is often limited to ultra-high vacuum conditions and cryogenic temperatures. Measurements under ambient conditions are influenced by variations of the dew point and thin water layers present on practically every surface, complicating stable imaging with high resolution. We demonstrate high-resolution imaging in air using a length-extension resonator operating at small amplitudes. An additional slow feedback compensates for changes in the free resonance frequency, allowing stable imaging over a long period of time with changing environmental conditions.

High-Resolution Frequency-Modulation Atomic Force Microscopy in Liquids Using Electrostatic Excitation Method

2010 ◽  
Vol 3 (6) ◽  
pp. 065205 ◽  
Author(s):  
Ken-ichi Umeda ◽  
Noriaki Oyabu ◽  
Kei Kobayashi ◽  
Yoshiki Hirata ◽  
Kazumi Matsushige ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
High Resolution ◽  
Frequency Modulation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Excitation Method

Laser cleaning of exfoliated graphene

2012 ◽  
Vol 1455 ◽  
Author(s):  
Oliver Ochedowski ◽  
Benedict Kleine Bußmann ◽  
Marika Schleberger
Keyword(s):  
Local Heating ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ambient Conditions ◽  
Kelvin Probe ◽  
Structural Modifications ◽  
Force Microscopy ◽  
Exfoliated Graphene ◽  
Atomic Force ◽  
P Type

ABSTRACTWe have employed atomic force and Kelvin-Probe force microscopy to study graphene sheets exfoliated on TiO2 under the influence of local heating achieved by laser irradiation. Exfoliation and irradiation took place under ambient conditions, the measurements were performed in ultra high vacuum. We show that after irradiation times of 6 min, an increase of the surface potential is observed which indicates a decrease of p-type carrier concentration. We attribute this effect to the removal of adsorbates like water and oxygen. After irradiation times of 12 min our topography images reveal severe structural modifications of graphene. These resemble the nanocrystallite network which form on graphene/SiO2 but after much longer irradiation times. From our results we propose that short laser heating at moderate powers might offer a way to clean graphene without inducing unwanted structural modifications.

Development of a Self-Excited Oscillator for SI-Traceable Measurements in Atomic Force Microscopy

2008 ◽  
Author(s):  
Gregory W. Vogl ◽  
Jon R. Pratt
Keyword(s):  
Atomic Force Microscopy ◽  
International System ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Transducers ◽  
Analog Control ◽  
System Of Units ◽  
Excited Oscillator

A new self-excited micro-oscillator is proposed as a velocity reference that could aid the dissemination of nanonewton-level forces that are traceable to the International System of Units (SI). An analog control system is developed to keep the actuation side of the device oscillating sinusoidally with an amplitude that is fairly insensitive to the quality factor. Consequently, the device can be calibrated as a velocity reference in air and used in ultra-high vacuum with a velocity shift of less than one percent. Hence, the calibrated micro-oscillator could be used with electrostatic forces to calibrate cantilevers used for atomic force microscopy (AFM) as SI-traceable force transducers. Furthermore, the calibrated micro-oscillator could potentially be used as an AFM sensor to achieve atomic resolutions on par with those realized in frequency-modulation AFM (FM-AFM) with quartz tuning forks.

Atomic-Force Microscopy with piezoresistive cantilevers

1994 ◽  
Vol 52 ◽  
pp. 1064-1065
Author(s):  
M. Tortonese ◽  
F. J. Giessibl
Keyword(s):  
Atomic Force Microscopy ◽  
Electron Tunneling ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Cantilever Deflection ◽  
Force Microscopy ◽  
Large Samples ◽  
Atomic Force ◽  
High Lateral Resolution ◽  
Piezoresistive Cantilevers

The atomic force microscope (AFM) works by measuring the deflection of a cantilever as it is scanned over a sample. A sharp tip at the end of the cantilever is responsible for the high lateral resolution achieved with the AFM. There are several ways to measure the deflection of the cantilever. The technique used to measure the deflection of the cantilever most often dictates the mechanical complexity and stability of the instrument. Electron tunneling, interferometry and capacitive sensors have been used successfully. The most common way to measure the cantilever deflection is by means of an optical deflection detector.The piezoresistivc cantilever offers a new way to measure the deflection of the cantilever, with performances comparable to the performances of other deflection detectors, and with the advantage that the sensor is incorporated in the cantilever. This simplifies the design and operation of the microscope In particular, the piezoresistive cantilever facilitates the use and often improves the performances of an AFM when operated in ultra high vacuum (UHV), at low temperature, or when used to image large samples.

scholarly journals Effect of the tip state during qPlus noncontact atomic force microscopy of Si(100) at 5 K: Probing the probe

2012 ◽  
Vol 3 ◽  
pp. 25-32 ◽  
Author(s):  
Adam Sweetman ◽  
Sam Jarvis ◽  
Rosanna Danza ◽  
Philip Moriarty
Keyword(s):  
Atomic Force Microscopy ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Dissipated Energy ◽  
Tunnel Current ◽  
Force Microscopy ◽  
Atomic Force ◽  
Wide Range ◽  
Characteristic Imaging

Background: Noncontact atomic force microscopy (NC-AFM) now regularly produces atomic-resolution images on a wide range of surfaces, and has demonstrated the capability for atomic manipulation solely using chemical forces. Nonetheless, the role of the tip apex in both imaging and manipulation remains poorly understood and is an active area of research both experimentally and theoretically. Recent work employing specially functionalised tips has provided additional impetus to elucidating the role of the tip apex in the observed contrast. Results: We present an analysis of the influence of the tip apex during imaging of the Si(100) substrate in ultra-high vacuum (UHV) at 5 K using a qPlus sensor for noncontact atomic force microscopy (NC-AFM). Data demonstrating stable imaging with a range of tip apexes, each with a characteristic imaging signature, have been acquired. By imaging at close to zero applied bias we eliminate the influence of tunnel current on the force between tip and surface, and also the tunnel-current-induced excitation of silicon dimers, which is a key issue in scanning probe studies of Si(100). Conclusion: A wide range of novel imaging mechanisms are demonstrated on the Si(100) surface, which can only be explained by variations in the precise structural configuration at the apex of the tip. Such images provide a valuable resource for theoreticians working on the development of realistic tip structures for NC-AFM simulations. Force spectroscopy measurements show that the tip termination critically affects both the short-range force and dissipated energy.

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