The field of self-assembled monolayers (SAMs) has witnessed tremendous growth in synthetic sophistication and depth of characterization over the past 15 years.1 However, it is interesting to comment on the modest beginning and on important milestones. The field really began much earlier than is now recognized. In 1946 Zisman published the preparation of a monomolecular layer by adsorption (self-assembly) of a surfactant onto a clean metal surface.2 At that time, the potential of self-assembly was not recognized, and this publication initiated only a limited level of interest. Early work initiated in Kuhn’s laboratory at Gottingen, applying many years of experience in using chlorosilane derivative to hydrophobize glass, was followed by the more recent discovery, when Nuzzo and Allara showed that SAMs of alkanethiolates on gold can be prepared by adsorption of di-n-alkyl disulfides from dilute solutions.3 Getting away from the moisture-sensitive alkyl trichlorosilanes, as well as working with crystalline gold surfaces, were two important reasons for the success of these SAMs. Many self-assembly systems have since been investigated, but monolayers of alkanethiolates on gold are probably the most studied SAMs to date. The formation of monolayers by self-assembly of surfactant molecules at surfaces is one example of the general phenomena of self-assembly. In nature, self-assembly results in supermolecular hierarchical organizations of interlocking components that provides very complex systems.4 SAMs offer unique opportunities to increase fundamental understanding of self-organization, structure-property relationships, and interfacial phenomena. The ability to tailor both head and tail groups of the constituent molecules makes SAMs excellent systems for a more fundamental understanding of phenomena affected by competing intermolecular, molecular-substrates and molecule-solvent interactions like ordering and growth, wetting, adhesion, lubrication, and corrosion. That SAMs are well-defined and accessible makes them good model systems for studies of physical chemistry and statistical physics in two dimensions, and the crossover to three dimensions. SAMs provide the needed design flexibility, both at the individual molecular and at the material levels, and offer a vehicle for investigation of specific interactions at interfaces, and of the effect of increasing molecular complexity on the structure and stability of two-dimensional assemblies. These studies may eventually produce the design capabilities needed for assemblies of three-dimensional structures.5 However, this will require studies of more complex systems and the combination of what has been learned from SAMs with macromolecular science. The exponential growth in SAM research is a demonstration of the changes chemistry as a disciAbraham Ulman was born in Haifa, Israel, in 1946. He studied chemistry in the Bar-Ilan University in Ramat-Gan, Israel, and received his B.Sc. in 1969. He received his M.Sc. in phosphorus chemistry from Bar-Ilan University in 1971. After a brief period in industry, he moved to the Weizmann Institute in Rehovot, Israel, and received his Ph.D. in 1978 for work on heterosubstituted porphyrins. He then spent two years at Northwestern University in Evanston, IL, where his main interest was onedimensional organic conductors. In 1985 he joined the Corporate Research Laboratories of Eastman Kodak Company, in Rochester, NY, where his research interests were molecular design of materials for nonlinear optics and self-assembled monolayers. In 1994 he moved to Polytechnic University where he is the Alstadt-Lord-Mark Professor of Chemistry. His interests encompass self-assembled monolayers, surface engineering, polymers at interface, and surfaces phenomena. 1533 Chem. Rev. 1996, 96, 1533−1554

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Formation and Structure of Self-Assembled Monolayers.

A few years after the invention of the scanning tunneling microscope (STM), the atomic force microscope (AFM) was developed Instead of measuring tunneling current, a new physical quantity could be investigated with atomic-scale resolution: the force between a small tip and a chosen sample surface This paper reviews progress and recent results obtained with AFM and other closely related techniques in the field of nanotribology, and attempts to point out many of the unresolved questions that remain The goal of this paper is to demonstrate that AFM is capable of producing atomic-scale knowledge As such, the authors will focus upon some of the contributions of the AFM to nanotribology They will almost exclusively discuss results that shed light on the actual atomic and molecular processes taking place, as opposed to the more applied investigations of microscale properties which are also carried out with AFM They will accompany this discussion by mentioning related theoretical efforts and simulations, although their main emphasis will be upon experimental results and the techniques used to obtain them, as well as suggested future directions In many ways, AFM techniques for quantitative, fundamental nanotribology are only in a nascent stage; certain key issues such as force calibration,more » tip characterization, and the effects of the experimental environment, are not fully resolved or standardized The authors thus begin with a critical discussion of the relevant technical aspects with using AFM for nanotribology 289 refs« less

/pdf/scratching-the-surface-fundamental-investigations-of-4kjq5s243s.pdf

Scratching the Surface: Fundamental Investigations of Tribology with Atomic Force Microscopy.

Electric field poled organic electro-optic materials: state of the art and future prospects.

Long-range surface plasmon polaritons (LRSPPs) are optical surface waves that
 propagate along a thin symmetric metal slab or stripe over an appreciable length
 (centimeters). Vigorous interest in LRSPPs has stimulated a large number of studies
 over three decades spanning a broad topical landscape. Naturally, a good segment of
 the literature covers fundamentals such as modal characteristics, excitation, and
 field enhancement. But a large portion also involves the LRSPP in diverse phenomena,
 including nonlinear interactions, molecular scattering, fluorescence,
 surface-enhanced Raman spectroscopy, transmission through opaque metal films and
 emission extraction, amplification and lasing, surface characterization, metal
 roughness and islandization, optical interconnects and integrated structures,
 gratings, thermo-, electro- and magneto-optics, and (bio)chemical sensing. Despite
 the breadth and depth of the research conducted to date, much remains to be
 uncovered, and the scope for future investigations is broad. We review the properties
 of the LRSPP, survey the literature involving this wave, and discuss the prospects
 for applications. Avenues for further work are suggested.

Long-range surface plasmon polaritons

Although a molecular monolayer is only a few nanometers thick it can completely change the properties of a surface. Molecular monolayers can be readily prepared using the Langmuir-Blodgett methodology or by chemisorption on metal and oxide surfaces. This Review focuses on the use of chemisorbed self-assembled monolayers (SAMs) as a platform for the functionalization of silicon oxide surfaces. The controlled organization of molecules and molecular assemblies on silicon oxide will have a prominent place in bottom-up nanofabrication, which could revolutionize fields such as nanoelectronics and biotechnology in the near future. In recent years, self-assembled monolayers on silicon oxide have reached a high level of sophistication and have been combined with various lithographic patterning methods to develop new nanofabrication protocols and biological arrays. Nanoscale control over surface properties is of paramount importance to advance from 2D patterning to 3D fabrication.

Engineering silicon oxide surfaces using self-assembled monolayers.

To evaluate the possibilities for preparing monolayer films from trichlorosilane derivatives containing aromatic functional groups, model studies of monolayer-forming trichlorosilanes which incorporate a phenoxy moiety in various positions of a long alkyl chain were undertaken. Self-assembled monolayers of several such compounds could be successfully formed. The properties of these monolayers have been evaluated by utilizing ellipsometry, wettability measurements, and FTIR and compared with analogous alkyltrichlorosilanes. Monolayers prepared from 1 -(trichlorosilyl)- 1 1 -(p-n-nony1phenoxy)undecane (1) show that the phenoxy group can be introduced into such monolayers with no loss of oleophobicity, as compared with octadecyltrichlorosilane (OTS), and with spectral features which indicate a high level of monolayer order and close packing. Linear dichroism measurements using FTIR-ATR are used to estimate the orientation of the alkyl chains and the phenoxy group in 1, and a model is proposed to explain the results. Shortening of the alkyl chain lengths in several examples led to more disordered, liquidlike monolayers. The orientation of the phenoxy group did not vary significantly with position in the alkyl chain. Interest in the formation of monolayers at a liquid-solid in- terface by spontaneous "self-assembly" has grown considerably in recent years with the discovery of methods that result in the formation of close-packed monolayers chemically bonded to the surface. These include the use of derivatives of trichlorosilane on hydroxylated surfaces, including glass, quartz, aluminum, and silicon (pioneered by the Sagiv group'"), and of thiol and disulfide monolayers on gold.'9* A particular advantage of the use of trichlorosilane systems is the application to the formation of ordered, cross-linked, multilayer structures. Such multilayer films can be constructed from molecules that terminate in a functional group that can be activated (e.g., a C=C bond or an ester group) to form a fresh hydroxylated surface, upon which a new monolayer can be ads~rbed.~~~-'' This technique, therefore, has great po- tential utility in the construction of macromolecular structures, or artificial lattices, with order at the molecular level and with electronic, electrooptic, or other "bulk" properties. We are interested in the eventual fabrication of multilayer structures that contain useful aromatic and other functional groups for eventual optical or electronic uses. However, most of the fundamental work on self-assembled monolayers, to date, has involved the study of monolayers of octadecyltrichlorosilane (OTS) and various similar, functional-group-terminated alkyltrichloro- silanes. Many potentially useful structures that may be built into such macromolecular structures contain aromatic or hetero- aromatic rings and possess symmetries different from cylindrical, long-chain alkyl groups. Hence incorporation of such groups into the alkyl chain will be accompanied by the introduction of disorder into the monolayer. The effect of this expected disorder on the packing of the monolayer, the orientation of the aromatic group and the alkyl chains, and the resultant quality of the monolayer and its surface properties are very important issues. Also im- portant are the effects of the position in the alkyl chain of the chromophore of interest on monolayer orientation, packing, and ~~~ ~~~~ ~~~

Incorporation of phenoxy groups in self-assembled monolayers of trichlorosilane derivatives. Effects on film thickness, wettability, and molecular orientation

A computer program product for detecting eye color defects of a subject in an image due to flash illumination comprises: a computer readable storage medium having a computer program stored thereon for performing the steps of detecting skin colored regions in a digital image; searching the skin colored regions for groups of pixels with color characteristic of redeye defect; and correcting color of the pixels based on a location of redeye defect found in step (b).

Computer program product for redeye detection

The use of the rate of change of the relative phase shift of p- and s-polarized light with voltage to determine the electrooptic coefficient of a poled polymer film is discussed.

Determination of the electrooptic coefficient of a poled polymer film.

An electrooptic modulator based on electrically varying the degree of coupling of a light beam to a long-range surface plasmon excitation is modeled. A specific embodiment of a modulator is shown to be capable of changing its reflectance from 0.00 to 0.84 on the application of 100 V across a 1-μm thick electrooptic film with a second-order susceptibility of 2 × 10−7 esu. The affect that the width of the long-range surface plasmon excitation resonance has on the performance of the modulator is considered. Plane-wave calculations show that decreasing the width of the resonance increases the amount of modulation possible for a given voltage change. More realistic calculations which take into account diffraction of a beam of finite width show that a decrease in resonance width can in some cases degrade device performance.

Long-range surface plasmon electrooptic modulator.

A mulitchannel optical waveguide page scanner has a diode laser and a primary optical channel waveguide. Light is coupled from the diode into the primary channel waveguide. Multiple secondary side channels each have a thin-film electro-optic waveguide modulator. A series of T-branch connectors distribute light from the primary channel to the secondary side channels. Each of the electro-optic waveguide modulators is addressable individually.

Jay S. Schildkraut

Papers

Incorporation of phenoxy groups in self-assembled monolayers of trichlorosilane derivatives. Effects on film thickness, wettability, and molecular orientation

Computer program product for redeye detection

Determination of the electrooptic coefficient of a poled polymer film.

Long-range surface plasmon electrooptic modulator.

Multichannel optical waveguide page scanner with individually addressable electro-optic modulators