Visible absorption spectrum of gaseous ferrocene

Abstract

The absorption spectrum of gaseous ferrocene was observed using intracavity laser photoacoustic spectroscopy in the spectral regions from 17800 to 15500 and 14300 to 11300 cm −1. The 4-0 CH stretching local mode transition appeared as a double peak at 11712 and 11669 cm −1. This new vibrational data combined with results of other workers allows us to propose a vibrational level pattern for the internal rotation and CH stretching mode of ferrocene. Broad absorptions peaking around 16250 and 13300 cm −1 were observed and assigned to the nonallowed d-d transitions. This is the first experimental observation of these extremely weak transitions in the gas phase. We estimate the molar extinction coefficient to be about 10 −2 M −1 cm −1.