Scanning tunneling microscopy procedure

The high lateral resolution down to the atomic scale is the special merit of scanning tunneling microscopy and spectroscopy. Spatially resolved measurements at T — 10 K with a W tip coated with approximately 10 ML Fe were performed on a sample prepared by depositing 10 ML of Gd on the W(llO) substrate held at 530 K. This preparation procedure leads to partially coalesced Gd islands with a Gd wetting layer on the W(llO) substrate. 

The use of electrochemical scanning tunnelling microscopy (EC-STM) in corrosion analysis reference material and procedural guidelines... 

Due to such advantages as high resolution that can approach the real atomic and molecular scale, and the ability to perform real-time measurement that cannot be matched by traditional microscopy, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) have attracted considerable attention since their introduction from researchers in various fields. The operational procedure of these microscopes is to position an atomically sharp detector needle to less than several nanometers from the surface of a sample, probe the interaction between the detector needle and the sample, scan the sample surface two-dimensionally, and obtain the surface image (an unprecedented method). If the interaction that is probed is the tunneling of the electron that is well known in quantum mechanics, the technique is called STM (T indicates tunneling). If, on the other hand, atomic force (van der Waals force) is used, it is called AFM. 

A double lamellae dropoff etching procedure for tungsten tips attached to tuning fork atomic force microscopy/scanning tunneling microscopy sensors. Rev. Sci. Instrum., 74, 1027-1030. 

The basical theories, equipments, measurement practices, analysis procedures and many results obtained by gas adsorption have been reviewed in different publications. For macropores, mercury porosimetry has been frequently applied. Identification of intrinsic pores, the interlayer space between hexagonal carbon layers in the case of carbon materials, can be carried out by X-ray dififaction (XRD). Recently, direct observation of extrinsic pores on the surface of carbon materials has been reported using microscopy techniques coupled with image processing techniques, namely scarming tunneling microscopy (STM) and atomic force microscopy (AFM) and transmission electron microscopy (TEM) for micropores and mesopores, and scanning electron microscopy (SEM) and optical microscopy for macropores [1-3],... 

Other techniques do not require surface pretreatment. Seanning probe microscopy was developed by Binnig et al. [64]. AFM is a newly developed characterization technique which shows promise for development and applieation in die field of microscopic observation and characterization of various surfaces. A very small tip scans die surface and moves vertically according to its interaction with die sample, similarly to what is done in STM. Both techniques differ in the method used to detect interactions. In STM die tip is close to die sample (both being eleetrieaUy conducting) allowing a current to flow by tunnel effect and die sample or tip moves to keep diis current constant In AFM die tip is placed on a cantilever whose deflection can be detected by die reflection of a laser beam appropriately focused. This allows analysis of nonconducting materials, which makes die method more eonvenient to study membrane materials [67-69]. Several procedures can be used for AFM ... 

---