Image monolayer

The importance of SPM for the study of monolayers is that it allows the visualization of the structure and defects of transferred and self-assembled monolayers on solid substrates at length scales from <0.1 nm to > 10 pm. It is not fyet ) possible to image monolayers at liquid/fluid Interfaces with SPM techniques. However, it has already been shown that it is feasible to measure interaction forces between a colloidal particle and such interfaces in the presence and absence of monolayers ). 

A particularly strong advantage of the BAM method is that it can be used to directly image monolayers formed by adsorption from the subphase. Phase transitions as a function of surface coverage, related to the subphase concentration, adsorption time, and temperature can be observed for such adsorbed monolayers. In one series of studies, the... 

Fig. 9.15 Schematic to show how the Si02 bilayer structures are constructed from the a-G configurations. The figure shows the process using the original network structure proposed by Zachariasen as an example (bottomleft) [1], The top left panel shows the (reverse engineered) a-G configuration. The top, centre and bottom right panels show the monolayer with the Si atoms pulled out of the original plane, the addition of the central O atom layer and the addition of the second, mirror image, monolayer respectively...

In the case of Langmuir monolayers, film thickness and index of refraction have not been given much attention. While several groups have measured A versus a, [143-145], calculations by Knoll and co-workers [146] call into question the ability of ellipsometry to unambiguously determine thickness and refractive index of a Langmuir monolayer. A small error in the chosen index of refraction produces a large error in thickness. A new microscopic imaging technique described in section IV-3E uses ellipsometric contrast but does not require absolute determination of thickness and refractive index. Ellipsometry is routinely used to successfully characterize thin films on solid supports as described in Sections X-7, XI-2, and XV-7. 

The ability to image lateral heterogeneity in Langmuir monolayers dates back to Zocher and Stiebel s 1930 study with divergent light illumination [166]. More recently the focus shifted toward the use of fluorescence microscopy of mono-layers containing a small amount of fluorescent dye [167]. Even in single-corn-... 

Fig. Vni-3. (a) Atomic force microscope (AFM) and (b) transmission electron microscope (TEM) images of lead selenide particles grown under arachidic acid monolayers. (Pi Ref. 57.)...

Berger C E FI, van der Werf K O, Kooyman R P FI, de Grooth B G and Greve J 1995 Funotional group imaging by adhesion AFM applied to lipid monolayers Langmuir 4188... 

Figure Bl.22.7. Left resonant seeond-hannonie generation (SHG) speetnimfrom rhodamine 6G. The inset displays the resonant eleetronie transition indueed by tire two-photon absorption proeess at a wavelength of approximately 350 mn. Right spatially resolved image of a laser-ablated hole in a rhodamine 6G dye monolayer on fiised quartz, mapped by reeording the SHG signal as a fiinetion of position in the film [55], SHG ean be used not only for the eharaeterization of eleetronie transitions within a given substanee, but also as a mieroseopy tool.

Static SIMS is labeled a trace analytical technique because of the very small volume of material (top monolayer) on which the analysis is performed. Static SIMS can also be used to perform chemical mapping by measuring characteristic molecules and fiagment ions in imaging mode. Unlike dynamic SIMS, static SIMS is not used to depth profile or to measure elemental impurities at trace levels. 

Element mapping with non-resonant laser- SNM S can be used to investigate the structure of electronic devices and to locate defects and microcontaminants [3.114]. Typical SNMS maps for a GaAs test pattern are shown in Fig. 3.43. In the subscript of each map the maximum number of counts obtained in one pixel is given. The images were acquired by use of a 25-keV Ga" liquid metal ion source with a spot size of approximately 150-200 nm. For the given images only 1.5 % of a monolayer was consumed -"static SNMS". 

Fig. 5.14. STM image of silicon covered with 1 /3 of a monolayer of silver [5.38].

SIMS has superb surface sensitivity since most of the secondary ions originate within a few nanometers of the surface and since high detection efficiency enables as little as 10 " of a monolayer to be detected for most elements. Because of its very high surface sensitivity, SIMS can be used to obtain depth profiles with exceptionally high depth resolution (<5 nm). Since the beam of primary ions can be focused to a small spot, SIMS can be used to characterize the surface of a sample with lateral resolution that is on the order of micrometers. Elements with low atomic numbers, such as H and He, can be detected, isotope analysis can be conducted, and images showing the distribution of chemical species across... 

Fig.9. SIM image of a monolayer of didodccylbenzcnc adsorbed on pyrolytic graphite from a phenyloctane solution. The area shown corresponds to 7.2 x 4.7 nm2 [37]. The strong features represent the benzene rings and the ordered arrangement of side groups is clearly resolved...

Fig. 18—Friction force images of L-B monolayer film, normal force 1 nN (scan range 2 /u.m). (a) Monolayer L-B film, (b) four-layer L-B films.

Figure 24 is a diagram of friction versus load derived from the friction force images of the above hgures. Figure 25 is also a diagram of friction versus load done in the same monolayer L-B him of C Q-Pst polymer but in a different scan range. 

Figure 35 shows the optical microscopic images of the first crack point on the sample surface. The scratch scar of monolayer Sample 1 has the feature of brittleness. However, there is an obvious crack along the scratch scar of Sample 2 before the coating delamination. This indicates that mono-layer Sample 2 has the feature of ductility, and the adhesion between the film and the substrate is poor. However, there is no obvious crack before the delamination in the scratch scars of other samples. The feature of multilayer Samples 3 and 4 is different from monolayer Samples 1 and 2. There are no obvious cracks in the scratch scars of Samples 5 and 6, except several small cracks along the edge of the scars. These... 

The surface viscosity varies significantly along the isotherm and across monolayer phase boundaries. Addition of subphase metal ions increases the surface viscosity drastically, as was recently reinvestigated [36]. Recently, microscopy methods have been used to image velocity profiles of different monolayer phases flowing through a narrow channel, such as used in the canal viscometer [37], The two main methods used to study monolayer viscosity are the canal viscometer and the oscillating disc method [8,9]. 

FIG. 6 (a) Brewster-angle microscopy (BAM) image of a monolayer of pentadecanoic acid at... 

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