Raman spectroscopy of mass-selected CrFe

We report on the resonance Raman spectroscopy of mass-selected CrFe. The molecule is isolated by sputtering a CrFe metal target, followed by mass-separation through a Wien filter. Samples are deposited in an argon matrix at 14 K. Raman spectra are obtained at several excitation wavelengths (476.5, 488.0, 496.5, 501.7, 514.5 nm) and a clear progression up to ν″=6 is obtained. Analysis results in values of ωe=166.6±0.8 cm−1 and ωexe=1.1±0.1 cm−1. This rather low frequency gives a force constant of 0.44 mdyne/Å, indicating considerably weaker bonding than observed in either Cr2 or Fe2.