ABSTRACT
NEXAFS spectroscopy investigates both bound and continuum state resonances of molecules observed in soft x-ray photoabsorption with exciting photon energies close to an absorption edge o f a selected constituent atom. While the resonance features above K-edges measured with organic materials are pretty broad due to short lifetimes, the experimental widths of the bound state resonances are rather small. In the case of polymers, sharp bound resonance features are most often correlated to C Is, N Is and O 1 s —> tt* transitions (when n bonds exist in the sample), thus, offering new possibilities for surface chemical analysis. Moreover, in the case of a preferential orientation of the polymer's segments and also with welloriented self-assembled monolayers, NEXAFS spectra measured in the angleresolved mode show a characteristic angle dependence3. Angle-resolved NEXAFS spectroscopy can be used here to exploit linear dichroism effects on non-isotropic surfaces. With the help of this special technique the effect o f metal evaporation on the orientation of an organic substrate can be studied to some extent in selected cases.
