Soft X-ray absorption and X-ray photoelectron spectroscopic study of tautomerism in intramolecular hydrogen bonds of N-salicylideneaniline derivatives

A combined study of typical SA derivatives by NEXAFS and XPS spectroscopies was examined. This was done by comparing the spectra of related compounds, polarization dependence for oriented samples and simulating the spectra by ab initio molecular orbita (MO) calculations of the core-excited states by the improved virtual orbital method. Results reveal that N1s and O1s XPS spectra showed double-peaked features characteristic of the mixture of the OH- and NH-forms. Furthermore, NEXAFS is useful for studying tautomerism, amorphous states and ultrathin films.