A new time-resolved Raman microspectrometer for the study of liquid-crystalline materials in thin cells

A new Raman microspectroscope was designed for the study of thin liquid-cry stalline films in glass cells. This system is based on a confocal geometry and a multi-channel liquid nitrogen cooled CCD detector. The confocal arran gement makes possible the study of volumes only a few mu m(3) in size withi n a liquid-crystal cell with an axial resolution of 7 mu m. The mutli-chann el detector allows high quality spectra to be recorded in less than a secon d with only a few milliwatts of laser power at the sample. Using an electro -optic modulator, dynamic studies can be done on the millisecond scale or s maller. We present the first results obtained with this technique of the el ectrical switching of a ferroelectric liquid-crystalline low molar mass org anosiloxane material.