Dichromium and trichromium

Abstract

Resonance and preresonance Raman spectra are obtained from chromium-containing argon matrics. Two progressions are assigned to Cr 2 and Cr3, the former with optical constants ωe = 427.5 and ωexe = 15.75 cm -1 and the latter with ωe = 313 and ωexe = 2 cm-1. When not in resonance two other lines at 123 and 226 cm-1 were observed and ascribed to the bending and asymmetric stretching vibration of Cr3, while the vibration forming the progression was taken to be the symmetric stretch. From this, Cr3 is deduced to be a molecule with C2v symmetry but with an apical angle near 60°, suggesting that it is perhaps a Jahn-Teller distorted D3h molecule. © 1982 American Institute of Physics.