ON THE FRANCK-CONDON EFFECTS IN THE ABSORPTION-SPECTRUM OF C10H8 ANION - THE ANALYSIS BASED ON THE AB-INITIO MCSCF METHOD

The near-IR, visible and UV regions of the absorption spectrum of naph thalene anion (C10H6-) are studied in terms of full optimized reaction space multiconfiguration self-consistent field method applied with Du nning's double-zeta basis set including polarization and diffuse funct ions on the all hydrogen atoms. Computed Franck-Condon activity of the all (nine) totally symmetric vibrations in the seven low-energy trans itions is discussed and compared to the available experimental data. T he assignment for some electronic transitions in the visible part of t he naphthalene anion absorption spectrum is corrected on the base of f ull optimized reaction space multiconfiguration self-consistent field computations. We have argued that two (overlapping) bands at 21700 cm( -1) and 26800 cm(-1) are due to 1(2)B(1g) --> 1(2)A(u) and 1(2)B(1g) - -> 2(2)A(u) transitions rather than to the short-axis and long-axis po larized ones as was suggested in an earlier semiempirical treatment. A n experimental method appropriate to verify this result is proposed.