Light-induced extinction originating from holographic scattering

We present extinction spectra of sodium nitroprusside exhibiting holographic light scattering after irradiation with coherent light. A characteristic extinction band appearing in the vicinity of the wavelength of the pump beam was discovered as well as an increase of the extinction coefficient over the whole spectral range. These features are proved to originate from diffraction of the probe beam from parasitic holograms and can be explained within the framework of a simple Ewald construction.