Atomic force microscopy imaging modes

FIGURE 7.1 Atomic force microscopy image of prednisolone-loaded Compritol nanoparticles produced by cold homogenization. Imaging was performed by using the noncontact mode. The formulation is composed of 5% Compritol, 1% prednisolone, 2.5% poloxamer 188, and 92.5% water. (From zur Miihlen, A. and Mehnert, W., Pharmazie, 53, 552-55, 1998. With permission.)... 

Fig. 2.55 (a) Atomic force microscopy image (constant force mode) of islands at the surface of a PS PUMA diblock (M = 82 kg mol1) copolymer film (Maaloum et al. 1992). The height of the islands is 310A. (b) Section of one domain with a diameter of Afim. (c) Assumed structure at the domain edge. 

Figure 6.10 Ambient contact mode atomic force microscopy images of an AgFON structure. The structure was made by depositing 200nm of Ag over 542 nm diameter polystyrene spheres, (a) The array of spheres and (b) image of one Ag-coated...

FIGURE 6.3 Atomic force microscopy images of silk films formed from reprocessed fibroin of B. mori. Two modes of processing are shown, all aqueous process (top), and methanol-induced 3-sheet transition... 

Figure 6.13 Height-mode atomic force microscopy images of poly(styrene-b-2-vinyl pyridine)/poly(methyl methacrylate) (PMMA) blend thin films with different compositions of PMMA (a) 10wt%, (h) 20wt%, (c) 30 wt%, (d) 40wt%, and (e) 50wt% at a fixed polymer concentration of 0.6 wt%.

Fig. 5. Hexagonal and stripe patterns observed via atomic force microscopy (Tapping Mode). Phase contrast images of (a) polystyrene-fe-poly(ethylene-co-butylene)-6-polystyrene, Kraton G1657 and (b) Kraton G1650 (82).

Figure 7 Tapping mode atomic force microscopy image of a PAM AMOS dendrimer-based network cast on mica surface (A), and the height profile associated with the line drawn on the image (B)...

Fig. 16. Atomic force microscopy images (tapping mode) for the failure surfaces. Image a was taken from the typical specimen tested under pure mode I, and image b was taken from the typical specimen tested under pure mode II.

Figure 9.3 Characterization of individual graphene oxide sheets (a) t)fpical tapping-mode atomic force microscopy image of graphene oxide sheets and (b) line profile for the sheet marked by the red fine in the image (Umer et al., 2015, with permission of Springer Science-I-Business Media).

Erlandsson R, Olsson L and Martensson P 1996 Inequivalent atoms and imaging mechanisms in AC-mode atomic force microscopy of Si(111)7 7 Phys. Rev. B 54 8309... 

FIGURE 12.10 Tapping mode atomic force microscopy (AFM) images of the section analyzes of ethylene-propylene-diene monomer (EPDM) rubber-melamine fiber composites. A, composite containing no dry bonding system B, composite containing resorcinol, hexamine, and silica in the concentrations 5, 3, and 15 phr, respectively. 

The shift of the amide I mode (FTIR spectra) from 1657 to 1646 cm-1 was attributed to a change in the a-helix native structure to fl-sheets, secondary structure conformations. Atomic Force Microscopy (AFM) images display the coating of the manganese oxide surface as well as the unfolding in a ellipsoidal chain of the protein molecules after adsorption and immobilization on the surface. 

The technique of atomic force microscopy (AFM) has permitted the direct observation of single polysilane molecules. Poly[//-decyl-(high molecular weight (4/w = 5,330,000 and Mn = 4,110,000), PSS, helicity, and rigid rod-like structure due to the aliphatic chiral side chains, was deposited from a very dilute (10-10 Si-unit) dm-3] toluene solution onto a (hydrophobic) atomically flat (atomic layer steps only present) sapphire (1012) surface. After drying the surface for a few minutes in a vacuum, AFM images were taken at room temperature in air in the non-contact mode.204,253 An example is shown in Figure 22, in which the polymer chain is evident as a yellow trace. 

A number of methods are available for the characterization and examination of SAMs as well as for the observation of the reactions with the immobilized biomolecules. Only some of these methods are mentioned briefly here. These include surface plasmon resonance (SPR) [46], quartz crystal microbalance (QCM) [47,48], ellipsometry [12,49], contact angle measurement [50], infrared spectroscopy (FT-IR) [51,52], Raman spectroscopy [53], scanning tunneling microscopy (STM) [54], atomic force microscopy (AFM) [55,56], sum frequency spectroscopy. X-ray photoelectron spectroscopy (XPS) [57, 58], surface acoustic wave and acoustic plate mode devices, confocal imaging and optical microscopy, low-angle X-ray reflectometry, electrochemical methods [59] and Raster electron microscopy [60]. 

The force microscope, in general, has several modes of operation. In the repulsive-force or contact mode, the force is of the order of 1-10 eV/A, or 10 -10 newton, and individual atoms can be imaged. In the attractive-force or noncontact mode, the van der Waals force, the exchange force, the electrostatic force, or magnetic force is detected. The latter does not provide atomic resolution, but important information about the surface is obtained. Those modes comprise different fields in force microscopy, such as electric force microscopy and magnetic force microscopy (Sarid, 1991). Owing to the limited space, we will concentrate on atomic force microscopy, which is STM s next of kin. 

Sulchek, T., R. Hsieh, J.D. Adams, G G. Yaralioglu, S.C. Minne, C.F. Quate, J.P. Cleveland, A. Atalar, and D. M. Adderton. 2000. High-speed tapping mode imaging with active Q control for atomic force microscopy. Appl. Phys. Lett. 76 1473-1475. See also note 159. 

---