Photodetachment band of the fluorenyl anion: a theoretical rationalization.

In order to rationalize the experimental photodetachment spectra of the fluorenyl anion, nuclear dynamics studies are performed using adiabatic and non-adiabatic quantum chemistry approaches. The adiabatic dynamics calculations are performed on the basis of _ and Poisson simulations. The outcomes from these simulations explain most of the experimental observations. Later, time-independent non-adiabatic nuclear dynamics calculations using vibronic coupling theory (VCT) are performed to elucidate the origin of a few vibrational peaks that do not appear in the results from adiabatic dynamics calculations. In addition, time-dependent non-adiabatic nuclear dynamics calculations using the same VCT approach are performed to rationalize the lifetime of the excited state of the fluorenyl anion. It is found that the photodetachment band obtained from the non-adiabatic simulations is in better agreement with the experimental findings.