About cookies on this site Our websites require some cookies to function properly (required). In addition, other cookies may be used with your consent to analyze site usage, improve the user experience and for advertising. For more information, please review your options. By visiting our website, you agree to our processing of information as described in IBM’sprivacy statement. To provide a smooth navigation, your cookie preferences will be shared across the IBM web domains listed here.
Paper
Structure and dynamics in a Langmuir-Blodgett film at elevated temperatures
Abstract
By a combination of waveguide Raman scattering, scanning microellipsometry and interference contrast microscopy some new structural details of Langmuir-Blodgett (LB) multilayers of cadmium arachidate on glass substrates have been determined. Raman measurements gave orientation and order as a function of temperature. Spectral changes, similar to those in the bulk, could be attributed to a progressive increase in librations of the hydrocarbon chain as the temperature was increased. Scanning microellipsometry on bilayer steps gave an upper limit for the lateral diffusion (D≤10-10 cm2 s-1), indicative of a solid phase at a temperature as high as 100°C. The optical thickness of a given multilayer decreased considerably on a time scale of 10 min, after an instantaneous temperature rise to 100°C. The initial loss of material apparently reflects the creation of voids needed to provide the additional space for the hydrocarbon chains to disorder. It was followed by a slower constant thermodesorption on a time scale of hours. This picture was supported by observations with an interference contrast microscope. Although films remained homogeneous upon heating to about 95°C, cracks were formed upon cooling to room temperature, probably a consequence of some ablation of chains at higher temperatures. Interestingly, the cracks were oriented mainly perpendicularly to the dipping direction, indicating some induced lateral structure. © 1988.