Browsing by Author "Baykara, Mehmet Z."

Now showing 1 - 6 of 6

Open Access
3D Force field spectroscopy
(Springer, Cham, 2015) Baykara, Mehmet Z.; Schwarz, U. D.; Morita, S.; Giessibl, F. J.; Meyer, E.; Wiesendanger, R.
With recent advances in instrumentation and experimental methodology, noncontact atomic force microscopy is now being frequently used to measure the atomic-scale interactions acting between a sharp probe tip and surfaces of interest as a function of three spatial dimensions, via the method of three-dimensional atomic force microscopy (3D-AFM). In this chapter, we discuss the different data collection and processing approaches taken towards this goal while highlighting the associated advantages and disadvantages in terms of correct interpretation of results. Additionally, common sources of artifacts in 3D-AFM measurements, including thermal drift, piezo nonlinearities, and tip-related issues such as asymmetry and elasticity are considered. Finally, the combination of 3D-AFM with simultaneous scanning tunneling microscopy (STM) is illustrated on surface-oxidized Cu(100). We conclude the chapter by an outlook regarding the future development of the 3D-AFM method.
Open Access
Atomic force microscopy: Methods and applications
(Elsevier, 2017) Baykara, Mehmet Z.; Schwarz, U. D.; Lindon, J.; Tranter, G. E.; Koppenaal, D.
This chapter provides an overview of atomic force microscopy, covering the fundamental aspects of the associated instrumentation and methodology as well as representative results from the literature highlighting a variety of application areas. In particular, atomic-resolution imaging and spectroscopy capabilities are emphasized, in addition to applications in biology, nanotribology and catalysis research. Finally, an outlook on emerging aspects and future prospects of atomic force microscopy is provided.
Open Access
Low-temperature scanning probe microscopy
(Springer, 2017) Baykara, Mehmet Z.; Morgenstern, M.; Schwarz, A.; Schwarz, U. D.; Bhushan, B.
This chapter is dedicated to scanning probe microscopy (SPM ) operated at cryogenic temperatures, where the more fundamental aspects of phenomena important in the fields of nanoscience and nanotechnology can be investigated with high sensitivity under well-defined conditions. In general, scanning probe techniques allow the measurement of physical properties down to the nanometer scale. Some techniques, such as scanning tunneling microscopy (STM ) and scanning force microscopy (SFM ), even go down to the atomic scale. Various properties are accessible. Most importantly, one can image the arrangement of atoms on conducting surfaces by STM and on insulating samples by SFM. However, electronic states (scanning tunneling spectroscopy), force interaction between different atoms (scanning force spectroscopy), magnetic domains (magnetic force microscopy), magnetic exchange interactions (magnetic exchange force microscopy and spectroscopy), local capacitance (scanning capacitance microscopy), local contact potential differences (Kelvin probe force microscopy), local temperature (scanning thermal microscopy), and local light-induced excitations (scanning near-field microscopy) can also be measured with high spatial resolution, among others. In addition, some modern techniques even allow the controlled manipulation of individual atoms/molecules and the visualization of the internal structure of individual molecules. Moreover, combined STM/SFM experiments are now possible, mainly thanks to the advent of tuning forks as sensing elements in low-temperature (LT) SPM systems. Probably the most important advantage associated with the low-temperature operation of scanning probes is that it leads to a significantly better signal-to-noise ratio than measuring at room temperature. This is why many researchers work below 100 K. However, there are also physical reasons to use low-temperature equipment. For example, visualizing the internal structure of molecules with SFM or the utilization of scanning tunneling spectroscopy with high energy resolution can only be realized at low temperatures. Moreover, some physical effects such as superconductivity or the Kondo effect are restricted to low temperatures. Here, we describe the advantages of low-temperature scanning probe operation and the basics of related instrumentation. Additionally, some of the important results achieved by low-temperature scanning probe microscopy are summarized. We first focus on the STM, giving examples of atomic manipulation and the analysis of electronic properties in different material arrangements, among others. Afterwards, we describe results obtained by SFM, reporting on atomic-scale and submolecular imaging, as well as three-dimensional (3-D ) force spectroscopy. Results obtained with the method of Kelvin probe force microscopy (KPFM ) that is used to study variations in local contact potential difference (LCPD ) are briefly discussed. Magnetic force microscopy (MFM ), magnetic exchange force microscopy (MExFM ), and magnetic resonance force microscopy (MRFM ) are also introduced. Although the presented selection of results is far from complete, we feel that it gives an adequate impression of the fascinating possibilities of low-temperature scanning probe instruments. In this chapter low temperatures are defined as lower than about 100 K and are normally achieved by cooling with liquid nitrogen or liquid helium. Applications in which SPMs are operated close to 0∘C are not covered in this chapter.
Open Access
Noncontact atomic force microscopy for atomic-scale characterization of material surfaces
(Springer, 2015) Baykara, Mehmet Z.; Kumar, C. S. S. R.
Among the large variety of scanning probe microscopy techniques, noncontact atomic force microscopy (NC-AFM) stands out with its capability of atomic-resolution imaging and spectroscopy measurements on conducting, semiconducting as well as insulating sample surfaces. In this chapter, we review the fundamental experimental and instrumental methodology associated with the technique and present key results obtained on different classes of material surfaces. In addition to atomic-resolution imaging, the use of NC-AFM towards the goal of atomic-resolution force spectroscopy is emphasized.
Open Access
Structural lubricity under ambient conditions
(Nature Publishing Group, 2016) Cihan, Ebru; İpek, Semran; Durgun, Engin; Baykara, Mehmet Z.
Despite its fundamental importance, physical mechanisms that govern friction are poorly understood. While a state of ultra-low friction, termed structural lubricity, is expected for any clean, atomically flat interface consisting of two different materials with incommensurate structures, some associated predictions could only be quantitatively confirmed under ultra-high vacuum (UHV) conditions so far. Here, we report structurally lubric sliding under ambient conditions at mesoscopic (∼4,000-130,000 nm2) interfaces formed by gold islands on graphite. Ab initio calculations reveal that the gold-graphite interface is expected to remain largely free from contaminant molecules, leading to structurally lubric sliding. The experiments reported here demonstrate the potential for practical lubrication schemes for micro-and nano-electromechanical systems, which would mainly rely on an atomic-scale structural mismatch between the slider and substrate components, via the utilization of material systems featuring clean, atomically flat interfaces under ambient conditions.
Open Access
Structure and nanotribology of thermally deposited gold nanoparticles on graphite
(Elsevier, 2015) Cihan, Ebru; Özoğul, Alper; Baykara, Mehmet Z.
We present experiments involving the structural and frictional characterization of gold nanoparticles (AuNP) thermally deposited on highly oriented pyrolytic graphite (HOPG). The effect of thermal deposition amount, as well as post-deposition annealing on the morphology and distribution of gold on HOPG is studied via scanning electron microscopy (SEM) measurements, while transmission electron microscopy (TEM) is utilized to confirm the crystalline character of the nanoparticles. Lateral force measurements conducted via atomic force microscopy (AFM) under ambient conditions are employed to investigate the nanotribological properties of the gold nanoparticles as a function of normal load. Finally, the increase in lateral force experienced at the edges of the nanoparticles is studied as a function of normal load, as well as nanoparticle height. As a whole, our results constitute a comprehensive structural and frictional characterization of the AuNP/HOPG material system, forming the basis for nanotribology experiments involving the lateral manipulation of thermally deposited AuNPs on HOPG via AFM under ambient conditions.