PHOTOCHROMISM OF 3-(3-PYRIDYL)SYDNONE - AN INVESTIGATION BY ELECTRON-SPECTROSCOPY FOR CHEMICAL-ANALYSIS (ESCA) AND MOLECULAR-ORBITAL CALCULATIONS

The electron spectra and core electron binding energies, obtained usin g ab initio STO-3G molecular orbital calculations of 3-(3-pyridyl)sydn one and the blue product of its photochromic transformation (N-(3-pyri dyl)-N-nitrosoaminoketene) are reported. The calculations yield the en ergies and shifts when the transformation from the colourless form to the coloured form takes place. The energy shifts are in good agreement with experimental data.