Scanning tunneling microscopy spatial resolution

For direct patterning on the nanometer scale, scanning probe microscopy (SPM) based techniques such as dip-pen-nanolithography (DPN), [112-114] nanograftingf, nanoshaving or scanning tunneling microscopy (STM) based techniques such as electron induced diffusion or evaporation have recently been developed (Fig. 9.14) [115, 116]. The SPM based methods, allows the deposition of as-sembhes into restricted areas with 15 nm linewidths and 5 nm spatial resolution. Current capabihties and future applications of DPN are discussed in Ref. [117]. 

The spectacular spatial resolution and relative ease of obtaining atomic resolution by scanning tunneling microscopy rests on three properties of the tunneling current ... 

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. 

SECM (Scanning electrochemical microscopy) is a technique to characterize the local electrochemical nature of various materials by scanning a probe microelectrode [1,2]. The spatial resolution of SECM is inferior to the conventional scanning probe microscopes such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM) as the fabrication of the probe, microelectrode, with nanometer sizes is quite difficult and the faradaic current of the microprobe is very small (often picoamps or less). However, SECM has unique characteristics that cannot be expected for STM and AFM SECM can image localized chemical reactions and it also can induce localized chemical reactions in a controlled manner. 

Table 7.1 A comparison of the sensitivity, and energy, time and spatial resolution of electrochemical methods, Raman spectroscopy and scanning tunneling microscopy (STM) in practical electrochemistry study...

---