X-RAY REFLECTIVITY ANALYSIS INCORPORATED WITH GENETIC ALGORITHM TO ANALYZE THE Y-TYPE TO X-TYPE TRANSITION IN CDA LB FILM

The structure and layer distribution of cadmium arachidate Langmuir-Bl odgett film were analyzed by the small angle X-ray reflectivity measur ements using synchrotron radiation. Y- to X type transition was occurr ed during the 39th passage of deposition of cadmium arachidate. Based on the measurement of the consumed area of the monolayer, it was deter mined that about 27.5 layer was deposited. Using the synchrotron X-ray , the: reflectivity profile of cadmium arachidate LB Nm over the wide range of grazing angle was obtained. The X-ray reflectivity profile wa s analyzed using the recursion formula. By fitting the location and di spersion of the subsidiary maxima between the Bragg peaks of the measu red reflectivity profile with that of the calculated reflectivity prof ile, the average thickness and the distribution of layer thickness wer e evaluated. The genetic algorithm was adopted to the fitting of refle ctivity profile to evaluate the optimum value of the number distributi on of layer. Based on the morphology measurement with an atomic force microscopy (AFM), the domain structure and mean roughness of LB films were obtained. The mean roughness value calculated based on the number of layer distribution obtained from the measurement by AFM is consist ent with that obtained from X-ray reflectivity analysis.