Nanochemical imaging

Hahner G, Marti A and Spencer N D 1997 The influence of pH on friction between oxide surfaces in electrolytes, studied with lateral force microscopy application as a nanochemical imaging technique Tribol. Lett. 3 359... 

Keywords AFM/LFM, lateral force (friction) signal, oxide (amphoteric) surfaces, pH, nanochemical imaging... 

Transmission electron microscopy (TEM) is a powerful and mature microstructural characterization technique. The principles and applications of TEM have been described in many books [16 20]. The image formation in TEM is similar to that in optical microscopy, but the resolution of TEM is far superior to that of an optical microscope due to the enormous differences in the wavelengths of the sources used in these two microscopes. Today, most TEMs can be routinely operated at a resolution better than 0.2 nm, which provides the desired microstructural information about ultrathin layers and their interfaces in OLEDs. Electron beams can be focused to nanometer size, so nanochemical analysis of materials can be performed [21]. These unique abilities to provide structural and chemical information down to atomic-nanometer dimensions make it an indispensable technique in OLED development. However, TEM specimens need to be very thin to make them transparent to electrons. This is one of the most formidable obstacles in using TEM in this field. Current versions of OLEDs are composed of hard glass substrates, soft organic materials, and metal layers. Conventional TEM sample preparation techniques are no longer suitable for these samples [22-24], Recently, these difficulties have been overcome by using the advanced dual beam (DB) microscopy technique, which will be discussed later. 

In this article, we describe the use of chemical imaging methods that rely on physical interactions (such as electrostatic and van der Waals) between chemically defined tips and organic surfaces, and focus on some of the problems that are specific to the nanochemical characterization of polymer surfaces. 

---