Structural Properties of Oligomeric Langmuir−Blodgett Films for Second-Order Nonlinear Optics

Abstract

Neutron reflection and infrared spectroscopy have been used to investigate molecular ordering in Langmuir−Blodgett films of oligomers for second-order nonlinear optical applications. The results are compared to those from a previous ellipsometric study. A high degree of order for the chromophores in the multilayer films is revealed by these experiments. In contrast, the hydrocarbon tails are either randomly oriented or highly tilted with respect to the substrate normal. To account for the reduced nonlinear optical activity in thick films, we suggest that some chromophores have become inverted during the deposition process.

Organic/Inorganic Langmuir−Blodgett Films Based on Metal Phosphonates. 3. An Azobenzene-Derivatized Phosphonic Acid Forms Continuous Lattice Layers with Divalent, Trivalent, and Tetravalent Metal Ions1

“…We refer to this molecule as A4 , where “ A ” indicates the azobenzene chromophore and “ 4 ” refers to the number of carbon atoms between the azobenzene moiety and the phosphonic acid headgroup. Azobenzenes have been widely studied in LB and self-assembled films with interests related to their optical properties, − nonlinear optical phenomena, − and the photochemically induced trans−cis isomerization reaction. − As a result, much is known about how azobenzene amphiphiles organize in LB films and how this organization can be probed with optical spectroscopy. We can therefore use the A4 molecule to investigate how functional organic molecules organize in LB films that contain different metal phosphonate inorganic continuous lattice layers.…”

Langmuir Film Polymerization of 1,22-Bis(2-aminophenyl)docosane: A Two-Dimensional Cross-linked Polyalkylaniline

“…Ultrathin films have been proposed for many applications such as in nonlinear optical − and electroluminescent devices , and sensors. , However, most applications require the films to be mechanically, thermally, and chemically stable under environmental conditions, which is often difficult to achieve. Polymeric systems are usually more stable than low molar mass analogues due to covalent bonding in the film plane and are often preferred …”