Molecular Crystals and Liquid Crystals, Vol.504, 114-123, 2009
Evaluation of Photoreactive Azo Dye Molecular Thin Films Utilizing an Optical Interferometer with Evanescent Wave Illumination
A new Mach-Zehnder type optical-interferometer utilizing evanescent wave illuminations of a reflected beam at a prism surface was constructed to evaluate photoreactive molecular thin films on a prism surface. Refractive index changes of the films due to photoisomerization of azo molecules on the prism caused by an irradiation beam were observed from phase changes between an incident beam and the reflected one at the prism surface. Real-time measurements were also demonstrated using the interferometer microscopy, exhibiting two dimensional distributions of the refractive indices in the molecular films partially excited by the focused irradiation laser beam.
Keywords:azo dye molecular film;evanescent wave interferometer;optical excitation;photoisomerization;refractive index