Quantum-Chemical Modeling of the Mass-analyzed Threshold Ionization Spectra of Ferrocene and Cobaltocene

The vibronic structures of the mass-selective threshold ionization spectra of ferrocene and cobaltocene are simulated within the framework of the density functional theory. Using (C 5 H 5 ) 2 Co as an example, it is shown that the proposed levels of theory reproduce well the peak positions and relative intensities in the experimental high-resolution spectrum. This makes it possible to predict accurately changes in the molecular structure and vibrational frequencies on the ionization of metallocenes in the gas phase.