Microscopia óptica e parâmetro de ordem em fases nemáticas

• Autor(a) principal: Oliveira, Davi Antunes de
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Estadual de Maringá (RI-UEM)
• Texto Completo: http://repositorio.uem.br:8080/jspui/handle/1/2634
• topic: Cristal líquido; Nemática calmítica; Coeficiente de absorção; Óptica; Dicronismo linear; Índice de refração; Parâmetro de Ordem; Brasil.; Calamitic nematic; Absorption Coefficient; Linear Dichroism; Order Parameter; Brazil.; Ciências Exatas e da Terra; Física

An investigation on refractive indices was undertaken throughout this work in three sequences of phases observed in the mixture SDS/DeOH/D2O. A study was carried out for the mixture KL/DeOH/D2O in order to identify the point of transition between the calamitic nematic and biaxial phases. The calamitic nematic phase (NC) was the object of study of the absorption anisotropy (Linear Dichroism) and of the order parameter. Measurements were taken in the visible region and the parallel ( ) and perpendicular ( ) absorption coefficients were determined according to temperature and wavelength for both lyotropic mixtures. The order of magnitude found for the parallel and perpendicular absorption coefficients was 10-6. The wavelength of maximum absorption for the KL system is at 550 nm and for the SDS system is at 589 nm. With the absorption coefficients data, it was determined the scale order parameter of the calamitic nematic phase and its dependence on temperature. The maximum value found for the order parameter was 0.46 for the KL system and 0.54 for the SDS.