Characterization of anisotropic organic layered films by resonant soft x-ray reflectivity

Reflectivity is typically carried out in the hard X-rays, where electron density contrast is exploited. In the soft X-rays, reflectivity at resonance provides additional advantages in terms of atomic and depth-resolved investigation of the chemical, structural and magnetic properties.
Our recent advances in the application of resonant soft X-ray reflectivity will be presented. In particular, we developed a protocol to get simultaneous quantitative information on the structure, interface morphology, chemical properties and optical anisotropies of layered organic materials with sub-nm depth resolution. The method is based on the quantitative prediction of the spectral line-shape across specific elemental edges. The calculated reflectivity, obtained by simulating the propagation of the electromagnetic field in a stack of layers, each described by a dielectric tensor derived from first principles calculations, is compared and fitted to the experiment.
The method has been successfully applied by us to study anisotropic thin and ultrathin organic films on metals and insulators.
In particular, the case of anisotropic growth of Cu-phthalocyanine films (up to 40 nm) on Au(110) will be presented.