An investigation of the transient absorption of vibrationally excited FH(CN-) centers revealed a structured side-band system that arose from vibronic transitions between various vibrational sub-states of the electronic ground and excited states. An analysis of the spectral and temporal behavior revealed a sharp change in the CN- vibrational frequency with optical excitation. The change in energy was associated with slight changes in the inter-nuclear distance; thus indicating weak linear coupling. With regard to the physical nature of the frequency change, the effect - at least in the FH(1) case - was much stronger than that typically produced by perturbations of the surrounding lattice. It was shown that this indicated a considerable weakening of the CN- bond. It was suggested that this was due to a transfer of the F center electron into an anti-bonding state that comprised the F center excited p orbital and orbitals of the CN- molecule.

D.Samiec, H.Stolz, W.Von der Osten: Materials Science Forum, 1997, 239-241, 469-72