Molecular electronic transition, saturation

This backdonation of electron density from the metal surface also results in an unusually low N-N streching frequency in the a-N2 state compared to the one in the y-N2 state, i.e. 1415 cm 1 and 2100 cm"1, respectively, for Fe(l 11)68. Thus the propensity for dissociation of the a-N2 state is comparatively higher and this state is considered as a precursor for dissociation. Because of the weak adsorption of the y-state both the corresponding adsorption rate and saturation coverage for molecular nitrogen are strongly dependent on the adsorption temperature. At room temperature on most transition metals the initial sticking coefficient does not exceed 10 3. 

Several attempts have been made to include Rydberg states within the INDO/S scheme, but they have not proven generally useful. See for example, D. R. Salahub and C. Sandorfy, Theor. Chim. Acta, 20, 111 (1971). CNDO, INDO, and RCNDO-CI Calculations on the Electronic Spectra of Saturated Hydrocarbons. W. Haque, /. Chon. Phys., 67, 3629 (1977). Use of the RINDO Method in Spectroscopy. Molecular Rydberg S -S and T<-T Transitions. 

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