Scanning probe microscopy resolution

High-resolution scanning probe microscopy (SPM) studies require flat surfaces at an atomic level. The preparation of flat surfaces is essential and is not a minor problem. This necessitates advanced understanding of surface reactivity and chemistry success has been obtained with silicon because systematic ex-situ studies of surface topography have been conducted by several groups. A good surface preparation is certainly more difficult with compound semiconductors because the different elements may dissolve at different rates. 

The ability to control the position of a fine tip in order to scan surfaces with subatomic resolution has brought scanning probe microscopies to the forefront in surface imaging techniques. We discuss the two primary techniques, scanning tunneling microscopy (STM) and atomic force microscopy (AFM) the interested reader is referred to comprehensive reviews [9, 17, 18]. 

Lillehei P T and Bottomley L A 2000 Scanning probe microscopy Ana/. Chem. 72 189R Sonnenfield R and Hansma P K 1986 Atomic-resolution microscopy in water Sc/ence 232 211... 

New types of scanning probe microscopies are continually being developed. These tools will continue to be important for imaging of surfaces at atomic-scale resolution. 

Scanning probe microscopy is a forefront technology that is well established for research in surface physics. STM and SFM are now emerging ftom university laboratories and gaining acceptance in several industrial markets. For topographic analysis and profilometry, the resolution and three-dimensional nature of the data is... 

Gao X, HameUn A, Weaver MJ. 1991. Potential-dependent reconstraction at ordered Au(lOO)-aqueous interfaces as probed by atomic-resolution scanning tunneling microscopy. Phys Rev Lett 67 618-621. 

Since the introduction of scanning tunnelling microscopy, a family of scanning probe microscopies (SPMs) have been developed (Table 3.1), with three main branches resulting from three different types of probe. All of the methods have in common the ability to image surfaces in real space at nanometre or better resolution, are straightforward to implement and are relatively low in cost. 

The already critical need for molecular-scale compositional mapping will increase as more complex structures are assembled. Currently, electron microscopy, scanning probe microscopy (SPM) and fluorescence resonance energy transfer (FRET) are the only methods that routinely provide nanometer 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]. 

Among the many microscopy-based techniques for the study of biomolecular interactions on surfaces, scanning probe microscopies, and especially the atomic force microscopies (AFM), are the most used because of their molecular and sub-molecular level resolution and in situ imaging capability. Apart from the high resolution mapping of siuface nanotopographies, AFM can be used for the quantification and visualisation of the distribution of chemistry, hydrophobicity and local mechanical properties on surfaces, and for the fabrication of nanostructmes on surfaces. 

There was, however, one topic which was not included in the first edition, which has undergone substantial development in the intervening years. It could have been foreseen in 1986 a paper was presented at the IEEE Ultrasonics Symposium entitled Ultrasonic pin scanning microscope a new approach to ultrasonic microscopy (Zieniuk and Latuszek 1986,1987). With the advent of atomic force microscopy, it proved possible to combine the nanometre-scale spatial resolution of scanning probe microscopy with the sensitivity to mechanical properties of acoustic microscopy. The technique became known as ultrasonic force microscopy, and has been joined by cognate techniques such as atomic force acoustic microscopy, scanning local-acceleration microscopy, and heterodyne force microscopy. 

There are numerous modern developments that have made atomic-scale resolution possible in recent years. In fact, some of these developments in instruments can also be used to measure forces between particles and surfaces. These developments for force measurements are discussed briefly in Section 1.6c and in Vignette 1.8. In this section, we review electron and scanning probe microscopies (SPMs), which allow atomic-scale visualization of surfaces and particles. 

---